Path switcher, and medium-transporting device and medium-processing apparatus including the same

A path switcher is provided at a point where a transport path along which a medium is to be transported branches out into a first branch path and a second branch path that are to be switched between by the path switcher. The path switcher includes: a switching component including a first arm and a second arm, the first arm being swingable at the point of branching of the transport path, the second arm being connected to a distal end of the first arm with an aid of a motion-allowing part, the switching component being configured to close one of the first branch path and the second branch path while opening an other of the first branch path and the second branch path; an elastic retaining component provided around the motion-allowing part and configured to elastically retain the first arm and the second arm in a predetermined positional relationship; and a rotary component rotatably provided at a distal end of the second arm and that is to come into contact with the medium.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2022-052970 filed Mar. 29, 2022.

BACKGROUND

(i) Technical Field

The present disclosure relates to a path switcher configured to switch the path along which a medium advances, and a medium-transporting device and a medium-processing apparatus each including the path switcher.

(ii) Related Art

Existing techniques relating to such a medium-transporting device include the one disclosed by Japanese Patent No. 4729966 (Description of Embodiments andFIG.1), for example.

Japanese Patent No. 4729966 (Description of Embodiments andFIG.1) relates to a paper-transporting technique in which a paper transport path on the downstream side relative to a nip part of a fixing device is secured between a guiding member and a supporting member provided across from the guiding member. The guiding member has a rib on which a transporting roller is provided. The supporting member is located close to the guiding member. When paper comes into contact with the supporting member, the paper receives a force acting in a direction toward the transporting roller.

SUMMARY

Aspects of non-limiting embodiments of the present disclosure relate to an operation of switching a transport path for a medium by using a switching gate provided at a point where the transport path branches out and to reducing the damage to the medium that may occur when the medium comes into contact with the distal end of the switching gate.

According to an aspect of the present disclosure, there is provided a path switcher provided at a point where a transport path along which a medium is to be transported branches out into a first branch path and a second branch path that are to be switched between by the path switcher, the path switcher including: a switching component including a first arm and a second arm, the first arm being swingable at the point of branching of the transport path, the second arm being connected to a distal end of the first arm with an aid of a motion-allowing part, the switching component being configured to close one of the first branch path and the second branch path while opening an other of the first branch path and the second branch path; an elastic retaining component provided around the motion-allowing part and configured to elastically retain the first arm and the second arm in a predetermined positional relationship; and a rotary component rotatably provided at a distal end of the second arm and that is to come into contact with the medium.

DETAILED DESCRIPTION

General Embodiment

FIG.1Aillustrates a medium-transporting device including a path switcher according to a general embodiment of the present disclosure.

The medium-transporting device illustrated inFIG.1Aincludes a first branch path11and a second branch path12branching out from a transport path10along which a medium S is to be transported, a path switcher1provided at a point of branching between the first branch path11and the second branch path12, and a transporting component (not illustrated) configured to transport the medium S.

In the general embodiment, as illustrated inFIGS.1A and1B, the path switcher1is provided at the point where the transport path10along which the medium S is to be transported branches out into the first branch path11and the second branch path12, which are to be switched between by the path switcher1. The path switcher1includes a switching component2, an elastic retaining component6, and a rotary component7. The switching component2includes a first arm3and a second arm4. The first arm3is swingable at the point of branching of the transport path10. The second arm4is connected to the distal end of the first arm3with the aid of a motion-allowing part5. The switching component2is configured to close one of the first branch path11and the second branch path12while opening the other. The elastic retaining component6is provided around the motion-allowing part5and elastically retains the first arm3and the second arm4in a predetermined positional relationship. The rotary component7is rotatably provided at the distal end of the second arm4and is to come into contact with the medium S.

Such a medium-transporting device is included in a medium-processing apparatus including a processing component (not illustrated) configured to perform a predetermined processing operation on a medium S, in which the medium-transporting device transports the medium S to the processing component or serves as a device that embodies a function of transporting the medium S processed by the processing component.

The term “processing component” used herein encompasses an imaging component configured to form an image on a medium S, and various other components configured to perform processing operations such as punching, cutting, sorting, and folding on a medium S.

In such a technical feature, the path switcher1is configured to switch the transport path between the two branch paths11and12and includes the swingable switching component2, the elastic retaining component6, and the rotary component7.

The switching component2is obtained by connecting the second arm4to the first arm3with the aid of the motion-allowing part5.

In the general embodiment, the first arm3is supported in such a manner as to be swingable about a pivot3a. The pivot3ais to be provided at a position between the first branch path11and the second branch path12and where the medium S does not pass.

The second arm4is movable relative to the first arm3within a range allowed by the motion-allowing part5. The first and second arms3and4are elastically retained at respective predetermined positions by the elastic retaining component6. Therefore, when the second arm4moves from the predetermined position, the second arm4receives an urging force generated by the elastic retaining component6in such a direction as to return the second arm4to the predetermined position. Hence, the elastic retaining component6is also regarded as an elastic member configured to return the distal end of the second arm4to the original position when the distal end of the second arm4is displaced relative to the distal end of the first arm3.

The rotary component7may typically be a runner roller that is rotatable on the axis thereof.

In the general embodiment employing the above configuration, the switching component2has the following functions: a basic path-switching function in which the combination of the first arm3and the second arm4swings about the pivot3a, and a damage-reducing function in which the damage to the medium S that may occur when the medium S comes into contact with the distal end of the switching component2is reduced.

The damage-reducing function according to the general embodiment is exerted as follows. When a medium S advancing toward the distal end of the switching component2comes into contact with the rotary component7and applies a contact pressure to the rotary component7, the rotary component7slightly retracts against the urging force exerted by the elastic retaining component6. Accordingly, the contact pressure between the medium S and the rotary component7is reduced. Therefore, the medium S is not strongly pressed against the rotary component7of the switching component2but causes the rotary component7to rotate and is directed by the switching component2toward the opened one of the branch paths11and12. In such a respect, the distal end of the switching component2is not formed as a fixed part but is provided with the rotary component7. The rotary component7comes into contact with the medium S at an appropriate contact pressure.

Now, a typical example of the path switcher1according to the general embodiment will be described.

In the typical example of the path switcher1, the first arm3is a flat plate extending in the width direction of the medium S that intersects the direction of transport of the medium S. The second arm4is a stick and is one of a plurality of second arms4arranged in the form of comb teeth at predetermined intervals in the width direction of the medium S. The rotary component7is one of a plurality of rotary components7provided to all or some of the plurality of second arms4in such a manner as to be arranged at intervals.

In the typical example, the first branch path11and the second branch path12are each defined by a defining member (not illustrated). The defining member has a recess in which the second arms4and the rotary components7are to be placed as a result of the switching motion of the switching component2. The recess of the defining member may have a space large enough for the second arms4to retract thereinto when the medium S comes into contact with the rotary components7. Such a configuration allows the second arms4to retract relative to the first arm3with the aid of the motion-allowing part5when the medium S comes into contact with the rotary components7. Thus, the impact applied from the distal end of the switching component2to the medium S is reduced.

In view of causing the medium S to appropriately come into contact with the rotary components7, an outer peripheral portion of each of the rotary components7may project toward the first branch path11or the second branch path12relative to the second arm4at a position where the rotary component7is attached to the second arm4. In such a configuration, the second arm4may be thinner on the side where the rotary component7is attached to the second arm4than on the side where the second arm4is connected to the first arm3.

In view of securing a long locus of swing of the switching component2about the pivot3a, the elastic retaining component6may be configured to retain the first arm3and the second arm4to be aligned in a substantially straight line. In the typical example, the elastic retaining component6may be a helical torsion spring wound around the motion-allowing part5and including two end hooks that are respectively made to engage with the first arm3and the second arm4.

The present disclosure will further be detailed on the basis of an exemplary embodiment illustrated in the other accompanying drawings.

Exemplary Embodiment

FIG.2outlines an image forming apparatus serving as a medium-processing apparatus according to the present exemplary embodiment.

Overall Configuration of Image Forming Apparatus

The image forming apparatus illustrated inFIG.2basically includes, in an apparatus housing20, an imaging engine21, a medium-transporting system80, and a fixing device70. The imaging engine21is configured to form an image composed of, for example, a plurality of color components. The medium-transporting system80is located below the imaging engine21and is configured to transport a medium to the imaging engine21. The fixing device70is configured to fix the image formed by the imaging engine21to the medium.

The imaging engine21according to the present exemplary embodiment includes image forming units22(specifically, 22a to22d), a belt-type intermediate transfer body30, and a second-transfer device (collective transfer device)50. The image forming units22are configured to form respective images in respective general color components (in the present exemplary embodiment, yellow (Y), magenta (M), cyan (C), and black (K)). The color-component images formed by the respective image forming units22are sequentially transferred to the intermediate transfer body30one of top of another (a first-transfer process). The color-component images thus carried by the intermediate transfer body30are transferred (collectively transferred) to a medium (a piece of paper or a film) by the second-transfer device50in a second-transfer process. The image forming apparatus illustrated inFIG.2is operated on an operation panel40.

Image Forming Unit

The image forming units22(22ato22d) according to the present exemplary embodiment each include a drum-type photoconductor23, which is surrounded by a charging device24, an exposure device25, a developing device26, a first-transfer device27, and a photoconductor-cleaning device28. The charging device24is a corotron, a transfer roll, or the like and is configured to charge the photoconductor23. The exposure device25is a laser scanning device or the like and is configured to form an electrostatic latent image on the charged photoconductor23. The developing device26is configured to develop the electrostatic latent image on the photoconductor23into a toner image with a toner of a corresponding one of the color components of Y, M, C, and K. The first-transfer device27is a transfer roll or the like and is configured to transfer the toner image from the photoconductor23to the intermediate transfer body30. The photoconductor-cleaning device28is configured to remove residual toner particles from the photoconductor23.

The intermediate transfer body30is stretched around a plurality (three in the present exemplary embodiment) of stretching rolls31to33. The stretching roll31, for example, serves as a driving roll to be driven by a driving motor (not illustrated). The intermediate transfer body30is rotated by the driving roll. The image forming apparatus further includes an intermediate-transfer-body-cleaning device35, which is provided between the stretching rolls31and33and is configured to remove residual toner particles from a part of the intermediate transfer body30that has undergone the second-transfer process.

The second-transfer device (collective transfer device)50is configured as follows, for example. A transfer roll55is pressed against the intermediate transfer body30at a position supported by the stretching roll33. The stretching roll33supporting the intermediate transfer body30serves as a counter roll56, which serves as a counter electrode for the transfer roll55. In the present exemplary embodiment, the transfer roll55includes a metal shaft provided therearound with an elastic layer made of a material such as urethane foam rubber or ethylene-propylene terpolymer (EPDM) containing carbon black or the like. A transfer voltage generated by a transfer power source (not illustrated) is applied to the counter roll56(also serving as the stretching roll33in the present exemplary embodiment) through a power-feeding roll (not illustrated) that is electrically conductive. Meanwhile, the transfer roll55is grounded. Thus, a predetermined transfer electric field is generated between the transfer roll55and the counter roll56. A site where the intermediate transfer body30is nipped between the transfer roll55and the counter roll56serves as a second-transfer site (collective transfer site) TR. While the second-transfer device50according to the present exemplary embodiment employs the transfer roll55, the second-transfer device50is not limited thereto. Needless to say, the second-transfer device50may be a transfer-belt module or the like including the transfer roll55serving as one of stretching rolls around which a transfer belt is stretched.

Fixing Device

The fixing device70includes a thermal fixing roll71and a pressure fixing roll72. The thermal fixing roll71is positioned to be in contact with an image-carrying surface of the medium and is rotatable when driven. The pressure fixing roll72is pressed against the thermal fixing roll71and rotates by following the thermal fixing roll71. The fixing device70allows the medium having an image to pass through a fixing site, which is defined between the two fixing rolls71and72. Thus, the image is fixed with heat and pressure applied thereto.

The thermal fixing roll71includes, for example, a heater provided inside a roll body thereof or is provided with an external heater to be brought into contact with the outer peripheral surface of the roll body, so that the roll body is heated. Needless to say, the pressure fixing roll72may also be provided with a heater. While the present exemplary embodiment concerns a case where the fixing device70employs a pair of rolls, the fixing device70is not limited thereto and may be selected from any of various devices. For example, the thermal fixing roll71may be replaced with a thermal fixing belt employing an induction heating scheme.

The medium-transporting system80includes a plurality (two in the present exemplary embodiment) of medium-supplying containers81and82. In the medium-transporting system80, a medium supplied from either of the medium-supplying containers81and82is transported to the second-transfer site TR through a vertical transport path83, which extends substantially vertically, and a horizontal transport path84, which extends substantially horizontally. Subsequently, the medium having received an image transferred thereto is transported by a transporting belt85to the fixing site in the fixing device70, and is discharged to an output-medium receiver86, which is provided on a lateral face of the apparatus housing20.

The medium-transporting system80further includes a transport-path branch87, which branches off downward from the horizontal transport path84at a position on the downstream side relative to the fixing device70in the direction of transport of the medium. The medium is turned over by being transported along the transport-path branch87. The medium thus turned over in the transport-path branch87is transported into a return transport path88, is fed into the vertical transport path83again, and is transported along the horizontal transport path84to the second-transfer site TR, where another image is transferred to the back side of the medium. Subsequently, the medium passes through the fixing device70and is discharged to the output-medium receiver86. The transport-path branch87branches out at a halfway point thereof to form a branch return path89. The medium having been turned over is transported along the branch return path89toward the output-medium receiver86.

The medium-transporting system80further includes a registration roll90, which sets the medium in position and then supplies the medium to the second-transfer site TR; an appropriate number of transporting rolls91, which are provided in the transport paths83,84,87,88, and89; and an output roll92, which is provided at the exit of the horizontal transport path84to the output-medium receiver86. Furthermore, the apparatus housing20is provided with a manual medium-feeding device95, which is located opposite the output-medium receiver86and allows the manual feeding of a medium into the horizontal transport path84.

Exemplary Branching Configuration of Transport Path Branching Point in Horizontal Transport Path

Referring toFIGS.2and3, the horizontal transport path84according to the present exemplary embodiment branches out at a halfway point thereof into two paths: the transport-path branch87and a straightforward transport path84a. The transport-path branch87extends downward and is intended to turn over the medium. The straightforward transport path84ais a part of the horizontal transport path84and extends straight ahead toward the output-medium receiver86.

The straightforward transport path84acorresponds to the first branch path inFIG.1A, and the transport-path branch87corresponds to the second branch path inFIG.1A.

A path switcher100is provided in the horizontal transport path84at a branching point E1(between the straightforward transport path84aand the transport-path branch87). A medium S transported from the upstream side along the horizontal transport path84is allowed to advance into one of the straightforward transport path84acorresponding to the first branch path and the transport-path branch87corresponding to the second branch path that are switched between by the path switcher100.

Branching Point in Transport-Path Branch

The transport-path branch87branches out at a branching point E2to form the branch return path89, which extends obliquely upward. With reference to the branching point E2between the transport-path branch87and the branch return path89, an upper transport-path branch87aextends upward while a lower transport-path branch87bextends downward. Seen from the lower transport-path branch87b, the transport path branches into two paths: the upper transport-path branch87aand the branch return path89.

In this case, the upper transport-path branch87acorresponds to the first branch path inFIG.1A, and the branch return path89corresponds to the second branch path inFIG.1A. The transport-path branch87is provided at the branching point E2with another path switcher100, whereby the upper transport-path branch87aand the branch return path89are switched between.

As illustrated inFIG.2, the transport-path branch87further branches out laterally to form the return transport path88at yet another branching point, where yet another path switcher (not illustrated) is provided.

Exemplary Arrangement of Transporting Rolls

Referring toFIG.3, the horizontal transport path84is provided at a position thereof immediately before the branching point E1with a transporting roll91a(91). The upper transport-path branch87aincluded in the transport-path branch87may be provided with a transporting roll91b(91), and the branch return path89may be provided with a transporting roll91c(91).

Exemplary Configuration of Path Switcher

In the present exemplary embodiment, the path switcher100is provided at each of the branching point E1in the horizontal transport path84, the branching point E2in the transport-path branch87, and other locations. All the path switchers100have the same configuration. Therefore, in the present exemplary embodiment, the path switcher100provided at the branching point E1in the horizontal transport path84will be described as an example.

Switching Gate

Referring toFIG.3, the path switcher100according to the present exemplary embodiment includes a switching member, which serves as a switching component that switches the transport path between the straightforward transport path84acorresponding to the first branch path and the transport-path branch87corresponding to the second branch path. In the present exemplary embodiment, a switching gate101is employed as the switching member. Referring toFIG.4andFIGS.5A and5B, the switching gate101includes a swing arm102and link arms103. The swing arm102corresponds to the first arm and is swingable at the branching point E1. The link arms103correspond to the second arm and are connected to the distal end of the swing arm102with the aid of a motion-allowing part104.

The swing arm102is molded as a single continuous member from, for example, synthetic resin such as acrylonitrile butadiene styrene (ABS) and includes an arm member110. The arm member110is a flat plate extending in the width direction of the medium S that intersects the direction of transport of the medium S. The arm member110is provided at the proximal end thereof with a pivotal shaft111, which corresponds to the pivot. The pivotal shaft111extends in the width direction of the medium S and projects from the two widthwise ends of the arm member110. The pivotal shaft11is rotatably supported at the branching point E1with the aid of bearings (not illustrated). The pivotal shaft111provided at the branching point E1is located at a position where the medium S does not pass.

The link arms103include respective stick-like arm members121, which are each molded as a single continuous member from, for example, synthetic resin such as ABS. The arm members121are arranged in the form of comb teeth at predetermined intervals in the width direction of the medium S. In side view, the arm members121each become thinner from the side thereof connected to the swing arm102toward the distal end thereof, thereby having a trapezoidal shape.

The motion-allowing part104includes a link shaft131, which has a D-shaped cross section and is fixedly provided. The link shaft131extends in the width direction of the medium S through a D-shaped through-hole132, which is provided in a connected part at the distal end of the arm member110of the swing arm102where the arm members121of the link arms103are connected to the swing arm102. The through-hole132receives the link shaft131with play δ (seeFIG.6C). With the motion-allowing part104including the link shaft131extending through the through-hole132provided in the link arms103, the link arms103are supported in such a manner as to be swingable by the play δ relative to the swing arm102. The link arms103may be molded individually, or a plurality of link arms103may be molded altogether.

Helical Torsion Spring

In the present exemplary embodiment, a helical torsion spring140serves as the elastic retaining component and is provided at each of the two ends of the motion-allowing part104. The helical torsion springs140each include a coil portion141, which is wound around the motion-allowing part104; and two end hooks142and143, which are respectively made to engage with the swing arm102and a corresponding one of the link arms103.

Thus, in the present exemplary embodiment, the helical torsion springs140elastically retain the swing arm102and the link arms103in a predetermined positional relationship. More specifically, referring toFIG.6C, the helical torsion springs140retain the swing arm102and each of the link arms103to be aligned in a substantially straight line with the flat part of the wall of the D-shaped through-hole132being in contact with the flat face of the D-shaped link shaft131.

Runner Rollers

In the present exemplary embodiment, referring toFIGS.4and5B, some of the plurality of link arms103are each provided at the distal end thereof with a runner roller150, which serves as the rotary component. In the present exemplary embodiment, six runner rollers150are provided at predetermined intervals.

The runner rollers150each include a roller body151, through the center of which a shaft152extends. The shaft152is rotatably supported at the distal end of the arm member121of a corresponding one of the link arms103. An outer peripheral portion of each of the runner rollers150projects toward the straightforward transport path84acorresponding to the first branch path or toward the transport-path branch87corresponding to the second branch path relative to the arm member121of the link arm103at the distal end of the arm member121where the runner roller150is attached. In the present exemplary embodiment, since the link arm103is thinner on the side thereof having the runner roller150than on the side thereof connected to the swing arm102, the outer peripheral portion of the runner roller150tends to project upward and downward relative to the distal end of the link arm103where the runner roller150is attached.

Driving System for Path Switcher

Referring toFIG.6A, the switching gate101according to the present exemplary embodiment is provided with a gate-driving mechanism160. The gate-driving mechanism160is provided at one end of the pivotal shaft111of the swing arm102and is configured to operate in Switching Mode I or Switching Mode II in accordance with a control signal received from a control device170. In Switching Mode I, the straightforward transport path84acorresponding to the first branch path is opened. In Switching Mode II, the transport-path branch87corresponding to the second branch path is opened.

Referring toFIG.6B, the gate-driving mechanism160according to the present exemplary embodiment includes a rotary shaft162. The rotary shaft162rotates synchronously with the shaft of a gate motor161. An eccentric cam163is fixed to one end of the rotary shaft162. The eccentric cam163has a substantially circular shape and includes a longer-radius portion RL, a shorter-radius portion RS, and a cam face. The longer-radius portion RLand the shorter-radius portion RSare located across the rotary shaft162from each other. On the other hand, the pivotal shaft111of the switching gate101is provided with a projecting arm164, which projects in the radial direction. The projecting arm164is provided at the distal end thereof with a roller165, which is rotatably in contact with the cam face of the eccentric cam163. The projecting arm164is urged against the cam face of the eccentric cam163by an urging spring (not illustrated).

In the present exemplary embodiment, a position detector166detects the angular position of the eccentric cam163. The position detector166includes a semicircular light-shielding plate167, which rotates coaxially with the eccentric cam163. The position detector166is configured to detect at which of the longer-radius portion RLand the shorter-radius portion RSthe eccentric cam163is in contact with the roller165of the projecting arm164by detecting whether an optical sensor168, which is a photocoupler or the like, is interrupted by the light-shielding plate167. The angular position of the eccentric cam163is controlled in accordance with the control signal issued by the control device170, and the projecting arm164is rotated within a predetermined angular range with reference to the relationship with the longer-radius portion RLor the shorter-radius portion RSof the eccentric cam163. Thus, the switching gate101is moved.

Exemplary Configuration of Elements Relevant to Path Switcher

The path switcher100according to the present exemplary embodiment includes the switching gate101. The switching gate101includes the link arms103arranged in the form of comb teeth. Some of the link arms103are provided at the distal ends thereof with the runner rollers150. The straightforward transport path84acorresponding to the first branch path and the transport-path branch87corresponding to the second branch path are each defined by a chute180, which corresponds to the defining member. Referring toFIG.7andFIGS.8A and8B, the chute180has recesses190, in which the link arms103and the runner rollers150are to be placed as a result of the switching motion of the switching gate101.

In Switching Mode I or Switching Mode II, the switching gate101is moved to such a position as to close a corresponding one of the branch paths. The recesses190are to be recessed at least to such an extent as to be able to receive the link arms103and the runner rollers150therein but not to allow the medium S to be drawn into the branch path that is closed by the switching gate101.

Specifically, at least a portion of each of the runner rollers150is to be placed within a corresponding one of the recesses190. In addition, the runner rollers150may be out of contact with the bottoms of the recesses190. To introduce the medium S into the opened one of the branch paths, the outer peripheral portions of the runner rollers150are to project into the opened branch path relative to the guiding surface of the chute180that defines the closed branch path.

Furthermore, the link arms103are to be placed in the recesses190such that the medium S is not drawn into the closed branch path and the link arms103do not interrupt the medium S that is guided toward the opened branch path. The link arms103when placed in the recesses190may be out of contact with the bottoms of the recesses190.

Exemplary Operation of Path Switcher

Switching Mode I

In Switching Mode I, referring toFIG.9A, the switching gate101closes the transport-path branch87corresponding to the second branch path to open the straightforward transport path84acorresponding to the first branch path.

In the present exemplary embodiment, the medium S guided toward the straightforward transport path84afirst comes into contact with the runner rollers150at the distal end of the switching gate101moved to close the transport-path branch87and is then guided along guiding surfaces of the link arms103and the swing arm102of the switching gate101.

In this process, when the medium S comes into contact with the runner rollers150, the runner rollers150receive from the medium S an external force F1, which pushes down the runner rollers150. When the external force F1that pushes down the runner rollers150is thus exerted, the swing arm102does not move but the link arms103temporarily retract against the urging force of the helical torsion springs140in such a manner as to rotate downward by the play δ about the motion-allowing part104. Accordingly, the contact pressure between the medium S and the runner rollers150is reduced. Therefore, the medium S is not strongly pressed against the runner rollers150of the switching gate101and causes the runner rollers150to rotate. Thus, the medium S is transported into the branch path opened by the switching gate101.

Furthermore, the link arms103and the runner rollers150of the switching gate101are placed into the recesses190provided in the chute180that defines the closed branch path (in the present exemplary embodiment, the transport-path branch87). Therefore, the medium S is not drawn into the closed branch path.

Switching Mode II

In Switching Mode II, referring toFIG.9B, the switching gate101closes the straightforward transport path84acorresponding to the first branch path to open the transport-path branch87corresponding to the second branch path.

In the present exemplary embodiment, the medium S guided toward the transport-path branch87first comes into contact with the runner rollers150at the distal end of the switching gate101moved to close the straightforward transport path84aand is then guided along guiding surfaces of the link arms103and the swing arm102of the switching gate101.

In this process, when the medium S comes into contact with the runner rollers150, the runner rollers150receive from the medium S an external force F2, which pushes up the runner rollers150. When the external force F2that pushes up the runner rollers150is thus exerted, the swing arm102does not move but the link arms103temporarily retract against the urging force of the helical torsion springs140in such a manner as to rotate upward by the play δ about the motion-allowing part104. Accordingly, the contact pressure between the medium S and the runner rollers150is reduced. Therefore, the medium S is not strongly pressed against the runner rollers150of the switching gate101and causes the runner rollers150to rotate. Thus, the medium S is transported into the branch path opened by the switching gate101.

Furthermore, the link arms103and the runner rollers150of the switching gate101are placed into the recesses190provided in the chute180that defines the closed branch path (in the present exemplary embodiment, the straightforward transport path84a). Therefore, the medium S is not drawn into the closed branch path.

In terms of evaluating the performance of the path switcher100according to the present exemplary embodiment, the performance of path switchers according to first and second comparative embodiments will now be examined.

First Comparative Embodiment

In the first comparative embodiment, the switching gate includes only the swing arm. Therefore, the distal end of the swing arm directly comes into contact with the medium.

In such a configuration, the following scheme tends to be employed. To eliminate the gap between the switching gate and the branch path, the swing arm has members arranged in the form of comb teeth at the distal end thereof. Furthermore, the recesses provided in each of the chutes that define the respective branch paths are shaped such that when a corresponding one of the branch path is closed by the switching gate, the comb teeth at the distal end of the switching gate extend beyond the guiding surface of the chute.

In such a scheme, however, when the medium comes into contact with the distal end of the switching gate, the comb teeth at the distal end of the swing arm tend to be strongly pressed against the medium. Consequently, linear scratches may be made in the medium.

Second Comparative Embodiment

In the second comparative embodiment, the switching gate includes runner rollers provided at the distal end of the swing arm. Therefore, the runner rollers directly come into contact with the medium.

In the second comparative embodiment, the runner rollers come into contact with the medium while rotating. Therefore, the frictional resistance generated between the medium and the runner rollers is smaller than in the case where the distal end of the swing arm directly comes into contact with the medium. However, in the process of guiding the medium toward the opened branch path, when the medium comes into contact with the runner rollers of the switching gate located in the closed branch path and applies an external force to the runner rollers, the swing arm does not move. Accordingly, the external force from the medium does not cause the runner rollers to retract. Therefore, the medium is guided toward the opened branch path while being strongly pressed against the runner rollers. Consequently, the medium tends to have linear marks made by the runner rollers.