JP2013245037A - Conveyance path switching mechanism for sheet-like member and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a conveyance path switching mechanism provided at a portion where a conveyance path for conveying a sheet-like member is branched to a plurality of conveyance paths, which suppresses collision sound of a switching pawl for guiding the sheet-like member to any conveyance path by rocking, and prevents the sheet-like member from being jammed at the branched portion of the conveyance path even if conveying speed of the sheet-like member is made high.SOLUTION: By making a butting part 62 of a switching pawl 6 abut on a stopper member 7 through an elastic member 72, the switching pawl 6 is kept at a predetermined switching position. Then, the collapse amount of the elastic member 72 caused by abutting of the switching pawl 6 at the predetermined switching position is adjusted by moving the stopper member 7.

Description

  The present invention relates to a sheet-like member conveyance path switching mechanism and an image forming apparatus including the same, and more particularly to a mechanism for switching a conveyance path by swinging a switching claw and an image forming apparatus including the mechanism. .

  Conventionally, when switching the conveyance path of a sheet-like member such as paper or a document in an image forming apparatus or the like, only one of the conveyance paths is opened by swinging a switching claw formed from resin or the like, and the other conveyance path Is closed and the conveyance path of the sheet-like member is switched.

  In such a conventional conveyance path switching mechanism, every time the switching claw is swung, the switching claw collides with a guide plate or the like constituting the conveyance path, and sometimes makes a loud collision sound.

  Therefore, in Patent Document 1, for example, an elastic member is provided on a member constituting the conveyance path, and when the rotating branching claw is overrun, the elastic member is brought into contact with the member constituting the conveyance path. Techniques have been proposed for preventing collision noise by preventing collision.

JP 2005-343620 A

  In forming each member including the elastic member, a dimensional tolerance is inevitably generated, and a positional deviation also occurs when each member is attached. For this reason, in the proposed technique, variation occurs in the amount of collapse of the elastic member when the switching claw contacts the elastic member. According to the experiment result of the present inventor, as shown in FIG. 6, the collision sound of the switching claw is inversely proportional to the crushing amount of the elastic member, and the collision sound increases when the crushing amount of the elastic member is small. For this reason, if the amount of collapse of the elastic member varies, the collision noise of the switching claw may not be sufficiently suppressed.

  Also, as shown in FIG. 7, the vibration attenuation time of the switching claw when the switching claw contacts the elastic member is also inversely proportional to the amount of collapse of the elastic member, and the vibration attenuation time becomes longer if the amount of collapse of the elastic member is small. . Note that the vibration attenuation time of the switching claw means a time until the vibration of the switching claw tip is settled when the switching claw comes into contact with the elastic member, for example, as shown in FIG. In recent years, as the image forming speed of the image forming apparatus is increased, the interval between sheets is becoming shorter. For this reason, when the vibration attenuation time of the switching claw is long, the leading edge of the conveyed paper may be pinched by being caught in the gap between the switching claw and the inner wall of the conveyance path. In particular, such a problem is likely to occur when the paper is curled.

  Accordingly, an object of the present invention is to suppress variation in the amount of crushing of the elastic member when the switching claw contacts the elastic member, to reliably suppress the collision sound of the switching claw, and even for curled paper An object of the present invention is to provide a conveyance path switching mechanism that can stably perform switching conveyance.

  Another object of the present invention is to provide an image forming apparatus in which the crushing noise of the switching claw is suppressed and no paper jam occurs at the branch portion of the conveyance path even if the sheet conveyance speed is increased.

  According to the present invention, there is provided a transport path switching mechanism provided at a portion where the transport path on which the sheet-like member is transported branches into a plurality of transport paths, and is provided on the base so as to be swingable. A switching claw that guides the sheet-like member to the base, a stopper member that is movably provided on the base, and that holds the switching claw in a predetermined switching position by contacting the switching claw; the switching claw and the stopper member; And an elastic member provided at the abutting portion, and the amount of collapse of the elastic member due to the abutment of the switching claw at a predetermined switching position can be adjusted by moving the stopper member. A conveyance path switching mechanism for the sheet-like member is provided.

  The elastic member may be provided on the stopper member.

  Further, it is preferable that the stopper member is movable in the circumferential direction around the swing axis of the switching claw.

  The switching claw may have an abutting portion, and the abutting portion and the stopper member may be in contact with each other via the elastic member.

  It is preferable that the distance of the contact portion from the swinging axis of the switching claw is in the range of 3 mm to 15 mm.

  The contact portion is preferably located in a region between the conveyance path and the conveyance direction downstream side of the sheet-like member from the swinging axis of the switching claw.

  According to the invention, in the image forming apparatus having a structure in which the conveyance path of the sheet-like member is branched into a plurality of conveyance paths, the conveyance path according to any one of claims 1 to 6 An image forming apparatus is provided that includes a switching mechanism.

  According to the transport path switching mechanism of the present invention, it is possible to suppress variation in the amount of collapse of the elastic member when the switching claw contacts the elastic member, and thus it is possible to reliably suppress the collision sound of the switching claw. Further, even a curled paper can be stably switched and conveyed.

  Further, according to the image forming apparatus of the present invention, the collision sound of the switching claw is suppressed, and even when the paper conveyance speed is increased, no paper jam occurs at the branch portion of the conveyance path.

1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. FIG. 2 is an enlarged cross-sectional view of a central portion in the axial direction of a branch portion of a conveyance path in the image forming apparatus of FIG. 1. FIG. 2 is an enlarged side view of an end portion in an axial direction of a branched portion of a conveyance path in the image forming apparatus of FIG. 1. It is a figure explaining a motion of a stopper member. It is a figure explaining other embodiment of a motion of a stopper member. It is a graph which shows the relationship between the crushing amount of an elastic member, and a collision sound. It is a graph which shows the relationship between the amount of collapse of an elastic member, and the vibration attenuation time of the front-end | tip height position of a switching claw. It is a graph which shows a time-dependent change of the tip height position of a switching claw.

  Hereinafter, the conveyance path switching mechanism and the image forming apparatus of the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic view showing an embodiment of an image forming apparatus provided with a transport path switching mechanism according to the present invention. The image forming apparatus D in FIG. 1 is a so-called tandem color printer. Of course, in addition to a printer, the present invention can also be applied to a copying machine having a scanner, a facsimile, or a multi-function machine having these functions combined. Further, the image forming method is not limited to the tandem method, and other methods, for example, four developing devices are arranged around the rotation shaft, and these are sequentially opposed to the electrostatic latent image carrier to be full color. A so-called four-cycle method of creating an image or a monochrome method of creating a monochrome image with one developing device may be used.

  The image forming apparatus D has an endless intermediate transfer belt 33. The intermediate transfer belt 33 is hung on a pair of rollers 31 and 32 disposed on both the left and right sides in the drawing. The roller 32 is connected to a motor (not shown), and the roller 32 rotates counterclockwise by driving the motor, whereby the intermediate transfer belt 33 and the roller 31 in contact therewith are driven to rotate. A secondary transfer roller 34 is in pressure contact with the outside of the belt portion supported by the roller 32. The toner image formed on the intermediate transfer belt 33 at the nip portion (secondary transfer region) between the secondary transfer roller 34 and the intermediate transfer belt 33 is transferred onto the conveyed paper P.

  A cleaning blade 34 for cleaning the surface of the intermediate transfer belt 33 is provided outside the belt portion supported by the roller 31. Untransferred residual toner is removed and collected at the contact portion of the cleaning blade 34 with the intermediate transfer belt 33.

  Below the intermediate transfer belt 33 suspended between the rollers 31 and 32, yellow (Y), magenta (M), cyan (C), black ( K) four image forming units 2Y, 2M, 2C, and 2K (hereinafter may be collectively referred to as “image forming unit 2”) are detachably disposed on the base 10. In these image forming units 2, a toner image of a corresponding color is created using each color developer.

  The image forming unit 2 has a cylindrical photosensitive member 20 as an electrostatic latent image carrier. A charging device 21, a developing device 23, a primary transfer roller 24, and a photoconductor cleaning device 25 are arranged around the photoconductor 20 in this order along the rotation direction (clockwise direction). The primary transfer roller 24 is in pressure contact with the photoconductor 20 with the intermediate transfer belt 33 interposed therebetween to form a nip portion (primary transfer region). An exposure device 22 is disposed below the image forming unit 2.

  In the embodiment shown in this figure, a roller charging type is used as the charging device 21, but the type of the charging device 21 is not particularly limited, and a corona discharge charging charger, a blade-shaped charging member, Of course, a brush-like charging member or the like may be used.

  Above the intermediate transfer belt 33, hoppers 26 </ b> Y, 26 </ b> M, 26 </ b> C, and 26 </ b> K that store toner to be supplied to the developing devices 23 of the respective colors are arranged. A paper feed cassette 50 is detachably disposed as a paper feed device below the exposure device 22. The sheets (sheet-like members) P stacked and accommodated in the sheet feeding cassette 50 are sent out one by one to the conveyance path in order from the uppermost sheet by the rotation of the sheet feeding roller 51 disposed in the vicinity of the sheet feeding cassette 50. The paper P sent out from the paper feed cassette 50 is conveyed to the registration roller pair 52 and is sent out to the secondary transfer area at a predetermined timing.

  The image forming apparatus D can be switched between a monochrome mode in which a monochrome image is formed using one color toner (for example, black) and a color mode in which a color image is formed using four color toners.

  An image forming operation example in the color mode will be briefly described. First, in each image forming unit 2, the outer peripheral surface of the photoreceptor 20 that is rotationally driven at a predetermined peripheral speed is charged by the charging device 21. Next, light corresponding to image information is projected from the exposure device 22 on the surface of the charged photoconductor 20 to form an electrostatic latent image. Subsequently, the electrostatic latent image is made visible by toner as a developer supplied from the developing device 23. When the toner image of each color formed on the surface of the photoreceptor 20 in this way reaches the primary transfer region by the rotation of the photoreceptor 20, the toner image is transferred from the photoreceptor 20 to the intermediate transfer belt in the order of yellow, magenta, cyan, and black. 33 is transferred (primary transfer) and superimposed.

  Residual toner remaining on the photoconductor 20 without being transferred to the intermediate transfer belt 33 is scraped off by the photoconductor cleaning device 25 and removed from the outer peripheral surface of the photoconductor 20.

  The superimposed four color toner images are conveyed to the secondary transfer region by the intermediate transfer belt 33. On the other hand, the paper P is conveyed from the registration roller pair 52 to the secondary transfer area in accordance with the timing. Then, the four color toner images are transferred (secondary transfer) from the intermediate transfer belt 33 to the paper P in the secondary transfer region. On the other hand, residual toner remaining on the intermediate transfer belt 33 without being transferred onto the paper P is scraped off by the belt cleaning device 34 and removed from the outer peripheral surface of the intermediate transfer belt 33. Thereafter, the rotational drive of each photoconductor 20 and the intermediate transfer belt 33 is stopped.

  The paper P on which the four color toner images are transferred is conveyed to the fixing device 9. In the fixing device 9, the paper P passes through the nip portion between the fixing roller and the pressure roller. During this time, the paper P is heated and pressurized, and the toner image on the paper P is melted and fixed on the paper P.

  The sheet P on which the toner image is fixed is conveyed to the branching portion through the conveying roller pair 53. In the case of single-sided printing, the paper P is guided to the first transport path 11 by the switching claw 6 of the transport path switching mechanism 1 and discharged to the paper discharge tray 14 by the discharge roller pair 54. On the other hand, in the case of duplex printing, the paper P is guided to the second transport path 12, switched back by the transport roller pair 55, and transported to the third transport path 13. Then, it is sent again to the registration roller pair 52 by the conveying roller pair 56, 57, 58, 59, and the toner image is secondarily transferred and fixed on the back side of the paper P in the same manner as described above.

  2 and 3 are schematic views of the transport path switching mechanism 1. FIG. FIG. 2 is a vertical sectional view of the central portion of the swinging shaft of the separation claw 6 in the axial direction, and FIG. 3 is a side view of the end portion in the axial direction. FIGS. 2A and 3A show a case where the paper P is guided to the first transport path 11, and FIGS. 2B and 3B show the paper P to the second transport path 12. This is the case for guiding.

  As shown in FIG. 2, the switching claw 6 has a substantially triangular shape and is provided on the base body 10 so as to be swingable about a swing shaft 61. The switching claw 6 has an abutting portion 62 that protrudes radially outward from the swing shaft 61. A stopper member 7 is provided on the base 10 so as to be movable in the vertical direction. An elastic member 72 is provided at a portion of the lower end portion of the stopper member 7 where the abutting portion 62 of the switching claw 6 contacts. When the switching claw 6 is in the first position for guiding the paper P to the first transport path 11, the abutting portion 62 of the switching claw 6 is separated from the elastic member 72 of the stopper member 7, and the switching claw 6 is When in the second position for guiding P to the second transport path 12, the abutting portion 62 of the switching claw 6 contacts the elastic member 72 of the stopper member 7.

  As shown in FIG. 3, a thin plate-like lever 8 is provided so as to be rotatable around a shaft 81 at the center in the longitudinal direction, a recess 82 is formed at one end of the lever 8, and the other end of the lever 8 is The solenoid 15 is connected to the plunger 16. A pin 63 protruding outward in the axial direction is formed at the axial end of the swinging shaft 61 of the switching claw 6 so as to be able to contact the recess 82 of the lever 8. Further, a tension coil spring S is interposed between the lever 8 on the plunger side of the shaft 81 and the base body 10, and the lever 8 is always urged counterclockwise by the tension coil spring S.

  As shown in FIG. 3A, when the solenoid 15 is off, the tension coil spring S rotates the lever 8 counterclockwise. As a result, the plunger 16 is pulled out from the solenoid body, and the concave portion 82 of the lever 8 comes into contact with the pin 63, so that the switching claw 6 rotates counterclockwise to the first position. On the other hand, as shown in FIG. 3B, when the solenoid 15 is turned on, the plunger 16 is drawn into the solenoid body, and the lever 8 rotates clockwise against the urging force of the tension coil spring S. As a result, the contact between the pin 63 and the recess 82 of the lever 8 is released, and the switching claw 6 rotates clockwise until the abutment portion 62 of the switching claw 6 contacts the elastic member 72 of the stopper member 4. Two positions.

  When the switching claw 6 is in the second position, that is, when the abutting portion 62 of the switching claw 6 contacts the elastic member 72, the amount of crushing of the elastic member 72 is adjusted by moving the stopper member 7 in the vertical direction. The Specifically, as shown in FIG. 4, a pin 17 formed on the base body 10 is engaged with a long hole 71 formed on the side surface of the stopper member 7 so as to protrude outward, and the stopper member 7 is The substrate 10 can be moved in the vertical direction. Then, by moving the stopper member 7 up and down while the solenoid 15 is on, the amount of collapse of the elastic member 72 by the abutting portion 62 of the switching claw 6 is adjusted to a predetermined amount. Thereby, as shown in FIG. 6, the variation in the amount of collapse of the elastic member 72 can be reduced as compared with the conventional case, and the collision sound of the switching claw 6 is reliably suppressed. Further, as shown in FIG. 7, the vibration attenuation time when the switching claw 6 abuts against the elastic member 72 is reduced compared to the conventional case, and a paper jam occurs at the branch portion of the conveyance path even if the paper conveyance speed is increased. Is prevented from occurring.

  The longer the distance from the swinging shaft 61 of the contact portion between the abutting portion 62 of the switching claw 6 and the elastic member 72, the smaller the vibration width at the tip position of the switching claw 6, so that at the branch portion of the conveyance path The occurrence of paper jams can be prevented, but there is a risk that the size of the apparatus will be increased. The distance from the rocking shaft 61 of the contact portion between the abutting portion 62 of the switching claw 6 and the elastic member 72 is preferably in the range of 3 mm to 15 mm.

  Further, the contact portion between the abutment portion 62 of the switching claw 6 and the elastic member 72 is the first conveyance path 11 and the second conveyance path 12 on the downstream side of the swinging shaft 61 of the switching claw 6 in the paper conveyance direction. If it is located in the area between, the size of the apparatus can be reduced, which is preferable.

  Furthermore, as shown in FIG. 5, when the stopper member 7 can be moved in the circumferential direction around the swing shaft 61, the elastic member 72 is crushed when the elastic member 72 and the abutting portion 62 come into contact with each other. The amount can be made uniform in the radial direction of the oscillating shaft 61, which is preferable.

  Examples of the elastic member 72 that can be used in the present invention include elastomers such as urethane rubber and silicone rubber, and foamed elastic bodies such as polyurethane foam.

  In the embodiment described above, the switching claw 6 is brought into contact with the stopper member 7 via the elastic member 72 when the switching claw 6 is in the second position. 6 may be brought into contact with the stopper member via the elastic member, and the amount of collapse of the elastic member may be adjusted by making the stopper member movable.

  According to the transport path switching mechanism of the present invention, it is possible to suppress variation in the amount of collapse of the elastic member when the switching claw contacts the elastic member, and thus it is possible to reliably suppress the collision sound of the switching claw. Further, even if the paper conveyance speed is increased, it is useful because no paper jam occurs at the branch portion of the conveyance path.

1 transport path switching mechanism 6 switching claw 7 stopper member P paper (sheet-like member)
DESCRIPTION OF SYMBOLS 10 Base body 11 1st conveyance path 12 2nd conveyance path 13 3rd conveyance path 61 Oscillation shaft 62 Abutting part 72 Elastic member

Claims (7)

A transport path switching mechanism provided at a portion where the transport path on which the sheet-like member is transported branches into a plurality of transport paths,
A switching claw that is swingably provided on the base and guides the sheet-like member to one of the conveyance paths;
A stopper member that is movably provided on the base body and holds the switching claw at a predetermined switching position by the contact of the switching claw;
An elastic member provided at a contact portion between the switching claw and the stopper member;
A transport path switching mechanism for a sheet-like member, wherein the crushing amount of the elastic member due to the contact of the switching claw at a predetermined switching position can be adjusted by moving the stopper member.   The transport path switching mechanism according to claim 1, wherein the elastic member is provided on the stopper member.   The transport path switching mechanism according to claim 1 or 2, wherein the stopper member is movable in a circumferential direction about a swing axis of the switching claw.   The conveyance path switching mechanism according to any one of claims 1 to 3, wherein the switching claw has a contact portion, and the contact portion and the stopper member abut via the elastic member.   The conveyance path switching mechanism according to any one of claims 1 to 4, wherein a distance of the contact portion from a swing axis of the switching claw is in a range of 3 mm to 15 mm.   The said contact part is located in the area | region between a conveyance path and a conveyance path in the conveyance direction downstream of a sheet-like member rather than the rocking | fluctuation axis | shaft of the said switching claw. Transport path switching mechanism.   In the image forming apparatus having a structure in which the conveyance path of the sheet-like member is branched into a plurality of conveyance paths, the conveyance path switching mechanism according to any one of claims 1 to 6 is provided at a portion where the conveyance path branches. An image forming apparatus.