JP2005112533A - Sheet direction turning device and image forming device equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet direction turning device structured simply and managing with a less occupation space. <P>SOLUTION: The sheet direction turning device 50 has a sheet guide path 51, whose one end serves as a sheet receptacle hole 53 and other end as a sheet sendout hole 54. At the sheet sendout hole 54, transport rollers 56 and 58 are installed in such an arrangement that the center line of a nip formed between them intersects perpendicularly the sheet intruding direction from the sheet receptacle hole 53. A first movable guide 60 and a second movable guide 65 installed working in combination with the transport rollers 56 and 58 can take the first attitude and the second attitude, and in the first attitude, they lead the leading edge of the sheet having intruded from the sheet receptacle hole 53 to one side of the rollers 56 and 58 to allow intruding to the nip, and in the second attitude, they lead the leading edge of the sheet to the other side of the rollers 56 and 58 to allow intruding to the nip. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to a sheet turning device and an image forming apparatus including the sheet turning device.

In an image forming apparatus such as a printer or a copier, the path for discharging a sheet after image formation is usually constant. However, a route different from the normal route may be prepared, and the sheet may be sent to another route according to printing conditions. In the case of duplex printing, or normally, the printing surface is discharged downward (face down), but the printing is reversed and the printing surface is discharged upward (face up). In such a case, a sheet turning device that changes the direction of the sheet so that the sheet is directed to a different path is required. An example of a sheet turning device can be seen in Patent Document 1.
JP-A-7-187470 (page 2-3, FIG. 2)

    The sheet turning device described in Patent Document 1 is provided with a conveyance path that intersects at one point from three directions so that the sheet can be distributed in the other two directions regardless of the direction from which the sheet is conveyed. Is complicated and has a large footprint.

    The present invention has been made in order to improve the above points, and provides a sheet turning apparatus that can distribute a sheet conveyed from one direction in two directions, has a simple structure, and requires less space. For the purpose. It is another object of the present invention to provide an image forming apparatus that facilitates the internal layout by mounting such a sheet turning device.

    (1) The sheet turning device of the present invention is configured by arranging two plates facing each other, with one end serving as a sheet receiving port and the other end serving as a sheet feeding port, and the sheet guiding unit. A pair of conveying rollers disposed at a sheet delivery port of the path in such a manner that a center line of a nip formed between them is perpendicular to a sheet entering direction from the sheet receiving port; a first posture; When the first posture is taken, the leading edge of the sheet entering from the sheet receiving port is guided to one side of the conveying roller to enter the nip, and the second posture is taken. A movable guide that guides the leading end of the sheet to the other side of the conveying roller and enters the nip, a driving unit that causes the movable guide to take one of the first and second postures, Said from the side According whether entering the-up, and a motor for rotating the conveying roller in a direction to draw the sheet into the nip.

    (2) In the present invention, the sheet turning device configured as described above is mounted on the image forming apparatus.

    (1) Since the sheet turning device is constituted by a pair of conveying rollers and a movable guide arranged in the sheet guiding path, a motor for rotating the conveying rollers forward and backward, and a driving means for switching the attitude of the movable guide, the structure is simple. Yes, the manufacturing cost is low. The pair of conveying rollers are arranged so that the center line of the nip formed between them is perpendicular to the sheet entering direction from the sheet receiving port of the sheet guiding path, that is, the sheet entering direction from the sheet receiving port. The two rollers are arranged side by side, and the sheet guide path is not thickened. For this reason, the sheet turning device is slim.

    (2) Since the slim sheet turning apparatus is mounted on the image forming apparatus as described above, the internal layout of the image forming apparatus is facilitated.

    Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic vertical sectional view of an image forming apparatus, FIG. 2 is a sectional view of a sheet turning apparatus, and FIGS. 3 and 4 are sectional views of the sheet turning apparatus taken at right angles to FIG. It is.

    The image forming apparatus 1 is a printer and includes a housing 10. The housing 10 includes a paper feeding unit 11 at the bottom and a paper discharge unit 12 at the top. A paper discharge tray 13 is attached to the side surface of the housing 10 so as to protrude to the opposite side of the paper discharge unit 12. A printed sheet is discharged to the paper discharge unit 12 in a face-down state, and a printed sheet is discharged to the paper discharge tray 13 in a face-up state. A vertical conveyance path 14 for conveying the sheet in the vertical direction is formed inside the housing 10. In the present specification, the terms “vertical” and “horizontal” are used as rough direction concepts, and are not restricted to the strict meaning of “vertical (vertical)” and “horizontal”.

    The lower end of the vertical conveyance path 14 is connected to the paper feeding unit 11. The upper part of the vertical conveyance path 14 is connected to a sheet turning device 50. The sheet turning device 50 sends the received sheet to the paper discharge path 15 or the paper discharge path 16. The paper discharge paths 15 and 16 are both horizontal, the paper discharge path 15 goes to the paper discharge unit 12, and the paper discharge path 16 goes to the paper discharge tray 13.

    A paper discharge roller 17 is disposed at the exit of the paper discharge paths 15 and 16. The paper discharge roller 17 is composed of a pair of rollers that are in contact with each other. When two rollers are paired in this way, they are called “XX rollers” in pairs. Conveying rollers 18 arranged at important points in the vertical conveying path 14 are also pair rollers.

    In the vertical conveyance path 14, the image forming unit 20 and the fixing unit 30 are disposed at a relatively low position. FIG. 1 shows a photosensitive drum 21 and a transfer roller 22 that presses a sheet against the photosensitive drum 21 in the image forming unit 20. The fixing unit 30 disposed on the downstream side of the image forming unit 20 includes a fixing roller 31 having a built-in heat source such as a halogen lamp, and a pressure roller 32 that presses against the fixing roller 31 and forms a nip through which a sheet passes.

    A switchback roller 43 is disposed above the fixing unit 30. The switchback roller 43 pulls back the sheet from the vertical conveyance path 14 and sends it to the duplex printing path 40 provided so as to be branched from the vertical conveyance path 14. A switching claw 41 for guiding the sheet toward the double-sided printing path 40 instead of the fixing unit 30 is disposed at a branch portion between the vertical conveyance path 14 and the double-sided printing path 40. The duplex printing path 40 joins the vertical conveyance path 14 upstream of the image forming unit 20. A conveyance roller 42 is disposed at a key point of the duplex printing path 40.

    Next, the structure of the sheet turning device 50 will be described with reference to FIGS. The sheet turning device 50 includes a vertical sheet guiding path 51. The sheet guide path 51 is configured by two symmetrical plates 52 facing each other. The sheet guide path 51 has a sheet receiving port 53 at the lower end and a sheet delivery port 54 at the upper end. The sheet receiving port 53 is narrow, whereas the sheet delivery port 54 is wide to accommodate a later-described transport roller.

    Two horizontal shafts are provided in parallel to each other at the sheet delivery port 54. One shaft is a drive shaft 55 disposed outside the sheet guide path 51, and a rubber conveyance roller 56 is fixed to the drive shaft 55. The other shaft is a support shaft 57 that can rotate within a predetermined angular range, and a synthetic resin transport roller 58 is rotatably attached thereto. The drive shaft 55 and the support shaft 57 overlap in the vertical direction. That is, as can be seen in FIG. 3, the line C connecting the center of the drive shaft 55 and the center of the support shaft 57 is vertical. The drive shaft 55 and the support shaft 57 are supported at both ends by bearings, but the bearings are not shown.

    The transport rollers 56 and 58 are the former driving roller and the latter driven roller, and come into contact with each other to form a nip. The center line of the nip is horizontal, that is, a shape perpendicular to the sheet entering direction from the sheet receiving port 53. The transport rollers 56 and 58 are each divided into four segments as shown in FIG.

    A movable guide is fixed to the support shaft 57. The movable guide includes a first movable guide 60 and a second movable guide 65, each of which is configured as follows. The first movable guide 60 is composed of a set of wedge-shaped guide plates 61 fixed to the support shaft 57. The guide plates 61 are fixed at predetermined intervals along the axis of the support shaft 57, and the front ends of the wedges are directed toward the sheet receiving port 53. The plate 52 is formed with a window 62 that receives the tip of the guide plate 61.

    The second movable guide 65 is a plate-like member disposed outside the sheet delivery port 54 and has a width that covers the entire width of the sheet guide path 51 in FIG. As shown in FIG. 3, both side edges of the second movable guide 65 are bent obliquely downward to form guide slopes 66L and 66R.

    Brackets 67 (see FIG. 2) are formed at both ends of the second movable guide 65, and the second movable guide 65 is fixed to the support shaft 57 with the bracket 67. When the support shaft 57 rotates, the first movable guide 60 and the second movable guide 65 rotate together. The second movable guide 65 is formed with a window 68 through which the conveying roller 56 passes.

    It is the motor 70 that rotates the drive shaft 55. A gear 71 fixed to the shaft end of the motor 70 meshes with a gear 72 fixed to one end of the drive shaft 55, whereby the power of the motor 70 is transmitted to the drive shaft 55. The motor 70 rotates forward and backward.

    The support shaft 57 is rotated by a fixed angle by the driving means. Here, the solenoid 75 constitutes a driving means. A lever 76 is fixed to one end of the support shaft 57, and a plunger 77 of a solenoid 75 is connected to the lever 76.

    The image forming apparatus 1 operates as follows. When performing single-sided printing, the sheet exiting the paper feeding unit 11 rises vertically toward the image forming unit 20. After the toner is transferred from the photosensitive drum 21 to the sheet, the fixing unit 30 fixes the toner by heat and pressure. The sheet after toner fixing continues to rise and enters the sheet turning device 50.

    When performing face-down paper discharge to the paper discharge unit 12, the first movable guide 60 and the second movable guide 65 take the posture shown in FIG. 3 (first posture). The motor 70 rotates the transport roller 56 in the direction of the arrow in FIG. 3, and the transport roller 58 that contacts the transport roller 56 also rotates in the direction of the arrow in FIG. The sheet that has entered the sheet guiding path 51 from the sheet receiving port 53 is guided by the first movable guide 60 so as to wrap around the left side (in FIG. 3) of the conveying rollers 56 and 58. In FIG. 3, the sheet trajectory is symbolized by a thick dashed line. The same applies to FIG.

    The sheet that has entered the left side of the conveying rollers 56 and 58 changes its direction when the leading edge hits the second movable guide 65 and enters the nip between the conveying rollers 56 and 58 from the left side. Thereafter, the sheet is drawn into the nip and sent to the paper discharge path 15. The sheet is further sent out face down from the paper discharge path 15 to the paper discharge unit 12.

    When performing face-up discharge on the discharge tray 13, the solenoid 75 switches the postures of the first movable guide 60 and the second movable guide 65 to take the posture shown in FIG. 4 (second posture). The motor 70 also reverses the direction of rotation, causing the transport rollers 56 and 58 to rotate in the direction of the arrow in FIG. The sheet that has entered the sheet guide path 50 from the sheet receiving port 53 is guided by the first movable guide 60 so as to wrap around the right side (in FIG. 4) of the transport rollers 56 and 58.

    The sheet that has turned around to the right side of the conveying rollers 56 and 58 changes its direction when the leading edge hits the second movable guide 65 and enters the nip between the conveying rollers 56 and 58 from the right side. Thereafter, the sheet is drawn into the nip and sent to the paper discharge path 16. The sheet is further sent out face-up from the paper discharge path 16 to the paper discharge tray 13.

    In the case of double-sided printing, the rotation direction of the switchback roller 43 is reversed when the trailing edge of the sheet on which single-sided printing has been completed approaches the switchback roller 43. If the sheet is sandwiched between the nips between the conveyance rollers 56 and 58, the rotation direction of the conveyance roller 56 is also reversed. If the sheet is sandwiched between the discharge rollers 17, the rotation direction of the discharge rollers 17 is also reversed. As a result, the sheet is pulled back and enters the double-sided printing conveyance path 40 without returning to the vertical conveyance path 13 by the action of the switching claw 41. The sheet is returned to the upstream side of the image forming unit 20 through the duplex printing conveyance path 40, and the toner is transferred and fixed on the remaining one side, and then sent to the sheet turning device 50 again.

    Since the conveying rollers 56 and 58 are arranged in the sheet entering direction from the sheet receiving port 53, it is not necessary to increase the width of the sheet feeding port 54 of the sheet guiding path 51. For this reason, the sheet turning device 50 is slimmed and the internal layout of the housing 10 is facilitated.

    Although one embodiment of the present invention has been described above, various modifications can be made without departing from the spirit of the present invention.

    The present invention can be used for a device that needs to select one of two directions and feed a sheet.

Model vertical sectional view of image forming apparatus Sectional view of sheet turning device A cross-sectional view of the sheet turning device, taken at a right angle to FIG. A cross-sectional view similar to FIG. 3, showing a different state from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Housing 11 Paper feed part 12 Paper discharge part 13 Paper discharge trays 15 and 16 Paper discharge path 20 Image forming part 30 Fixing part 40 Duplex printing path 50 Sheet turning device 51 Sheet guide path 53 Sheet receiving port 54 Sheet sending out Ports 56 and 58 Conveying roller 60 First movable guide 65 Second movable guide 70 Motor 75 Solenoid (driving means)

Claims (2)

Sheet turning device with the following configuration:
(A) a sheet guiding path that is configured by arranging two plates facing each other, with one end being a sheet receiving port and the other end being a sheet feeding port; (b) a sheet feeding port of the sheet guiding channel; A pair of conveying rollers (c) arranged in a form in which a center line of a nip formed between them is perpendicular to a sheet entering direction from the sheet receiving port, and takes a first posture and a second posture. When the first posture is taken, the leading edge of the sheet entering from the sheet receiving port is guided to one side of the conveying roller to enter the nip, and when the second posture is taken, the leading edge of the sheet (D) A driving means for causing the movable guide to take one of the first and second postures.
(E) A motor that rotates the transport roller in a direction in which the sheet is drawn into the nip depending on from which side the sheet enters the nip.   An image forming apparatus comprising the sheet turning device.

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