JP3246963B2 - Sheet transport path switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer path switching device for a branch provided in a sheet transfer path of an image forming apparatus such as an electrophotographic copying machine or a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a printer, as shown in FIG. 9, a recording sheet fed from a sheet feeding section 34 and having an image formed on one side by an image forming section 30 is branched into a branch section. 35, the first transport path 2 leading to the paper discharge unit 31 outside the machine,
Alternatively, the paper is selectively conveyed to any one of the second conveyance paths 3 leading to the re-feeding unit 33 having the reversing unit 32 for forming an image on the back surface, and is re-fed from the re-feeding unit 33 to the image forming unit 30. The recording paper with the image formed on the back side
The paper is discharged to the paper discharge unit 31 via the transport path 2.

[0003] As described above, in the branch portion 35,
Conventionally, a switching claw 50 as shown in FIG. 10 is used as a device for switching the sheet conveyance direction to the first and second conveyance paths 2 and 3.
Is provided in the branching section 35, and a gate system that switches the position of the switching claw 50 by a solenoid (not shown) and conveys the sheet 4 conveyed from the conveying roller 5 on the upstream side of the branching section to a selected conveyance path is widely used. Have been. Branch claw 50
Is set to a position that closes the second transport path 3 as indicated by a solid line, the sheet 4 is fed into the first transport path 2 and
As shown by a broken line, the sheet 4 is fed into the second transport path 3 when the first transport path 2 is closed.

However, in the transport path switching apparatus of this type, when the branch claw 50 is switched while the sheet is being transported to the branch section 1, the sheet being transported is moved between the tip of the branch claw 50 and the guide plate. The sheet is strongly sandwiched by the above and jams and damage to the sheet occur, so it is necessary to feed the sheet with a large sheet interval, which is not suitable for high-speed switching.

[0005] An air suction type paper switching apparatus which improves this point and enables high-speed switching is disclosed in Japanese Patent Application Laid-Open No. 60-524.
No. 55 discloses this. This apparatus provides suction ports on both sides of the conveyance path immediately upstream of the branching section, and when the sheet leading edge passes through this position, activates the suction port on the side of the selected path to move the sheet leading edge toward the sheet leading side. By pulling,
The sheet is guided to the selected route.

[0006] Although this system is capable of high-speed switching, it is not practical because the suction device has a large disadvantage such as an increase in the size of the device, an increase in cost, and the generation of noise.

[0007] In view of the above-mentioned problems of the gate system using the branch claws and the air suction system, the present applicant has previously prepared FIG.
As shown in the figure, a switching roller 1 that can be rotated forward and backward is provided at a branch portion 35, and the peripheral surface of the switching roller 1 that rotates the leading end of the sheet 4 conveyed from a pair of conveying rollers 5 on the upstream side in either direction. And a conveyance path switching device that guides the sheet to one of the conveyance paths when the sheet is selected by the action force between the sheet leading end and the switching roller 51.

In the figure, when the switching roller 1 rotates counterclockwise as indicated by the solid line arrow, the sheet 4 whose leading end abuts on it is guided to the first transport path 2 as indicated by the solid line, and the switching roller 1 rotates. Is rotated clockwise as indicated by the dashed arrow, the sheet 4 whose leading end abuts on it is guided to the second transport path 3 as indicated by the dashed line.

Since the conveyance path is switched by switching the rotation direction of the switching roller, the switching operation can be performed regardless of whether or not a sheet exists in the branch portion, and high-speed switching can be performed regardless of the sheet interval. Can be.
Further, since there is no suction operation of the solenoid, no sudden sound is generated and a low-cost and highly reliable switching device can be realized.

However, since the switching roller needs to switch the rotation direction between forward and reverse in accordance with the transport path to be guided, the configuration of the driving source is slightly complicated, the cost is increased, and the sheet is transmitted to either path. However, there is a disadvantage that it is necessary to drive the switching roller when guiding the guide.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances of a conventional sheet conveying path switching apparatus, and has a low cost and a low power consumption in a sheet conveying path switching apparatus using a switching roller capable of high-speed switching. It is an object of the present invention to provide a transport path switching device capable of switching a transport path reliably, at high speed, and with high reliability.

[0012]

According to the present invention, in order to solve the above-mentioned problems, a switching roller provided at a branch portion can rotate only in one direction, and in a state where the switching roller is stopped, The sheet is guided to the first conveyance path at an angle at which the leading edge of the conveyed sheet abuts on the peripheral surface of the switching roller. When the switching roller is rotating, the sheet is brought into contact with the peripheral surface of the rotating roller. The sheet is guided to the second transport path by an action force between the sheet and the leading edge of the sheet.

[0013]

With the above construction, the switching roller needs to be rotated in one direction only when guiding the sheet to the second conveying path, and the driving means and the control means for the switching roller are simplified and the size is reduced. Power consumption, and life and reliability are improved. Further, the use of the switching roller eliminates the occurrence of sudden sound as in the case of using a solenoid.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1A is a diagram showing an embodiment of the present invention. In the figure, a first transport path 2 and a second transport path 3
The switching roller 1 provided at the branch portion of the sheet feeder is configured such that the leading end of the sheet 4 conveyed by the pair of conveyance rollers 5 provided on the upstream conveyance path of the branch portion abuts on the roller 1 above the axis thereof and moves upward. It is provided at a position where it slips.

Therefore, when the sheet 4 conveyed by the upstream conveying roller 5 at the branch point comes into contact with the peripheral surface of the switching roller 1 which has stopped rotating, it slides upward and slides on the peripheral surface of the roller 1. It is guided toward the first transport path 2.

FIG. 1B shows a state in which the sheet 4 is transferred to the second conveying path 3.
The switching roller 1 is driven to rotate clockwise as shown by an arrow in the figure, and the leading end of the sheet 4 conveyed from the upstream side of the branch point is rotated by the switching roller 1. Upon impact, the leading end of the sheet is entrained by the rotation of the roller 1 due to the acting force between the roller 1 and is guided toward the second transport path 3 as shown in the figure. Sheet tip and roller 1
It is easy to use the frictional force of the material as the acting force for engaging the outer peripheral surface of the switching roller 1 without slipping.
It is desirable to select a material having a large coefficient of friction, such as rubber, for the material. Also, as shown in the figure, it is effective to carry out brush-like flocking. However, in such a case, it is necessary to take care that the leading edge of the sheet is not caught and hinders the movement of the leading edge of the sheet to the first transport path.

FIG. 2 shows one example of the countermeasure, in which the brush raising direction is slid in the first transport direction like a brush for removing dust from clothes by sliding the brush raising direction to a sticker on the lower surface of the ski or to one side. It is conceivable to tilt it.

However, in such a case, it is unavoidable that the acting force for guiding the sheet to the second transport path is slightly reduced.

In order to solve this problem, the stop position of the switching roller is set to a constant rotation angle position, and the gap between the leading end of the sheet and the peripheral surface of the switching roller when the switching roller is stopped at that position. In this case, the acting force for guiding the sheet to the first transport path may be increased.

FIGS. 3 (a) and 3 (b) show an embodiment in which such a configuration is used. In the embodiment shown in FIG. 3 (a), the roller 1 is partially cut away to form a missing circular cross section, and no hair is implanted in the missing circular portion. Abuts on the leading end of the sheet 4 conveyed from the upstream side obliquely, smoothly slides and guides the sheet 4 to the first conveying path. Roller 1
The other peripheral surface is planted, and if the roller 1 rotates,
The leading end of the sheet 4 conveyed from the upstream side is brought to the second conveyance path without slipping due to flocking.

In the embodiment shown in FIG. 3 (b), the roller 1 has a flat elliptical cross section. When the roller 1 is at the stop position, the length of the cross section of the roller in the guide direction of the sheet conveyed from the upstream of the branch portion is reduced. The directions are substantially matched. And
Hair is planted only near both ends of the major axis. Therefore, when the roller 1 is stopped, the sheet 4 conveyed from the upstream side is guided to the first conveying path 2 by the substantially flat surface of the roller 1, and the tip of the sheet 4 is rotated by the clockwise rotation of the roller 1. 1 and the second transport path 3
It is led to.

At the time of stoppage, the switching roller 1 is moved to the position shown in FIG.
In order to stop at a rotation angle position where a predetermined posture shown in (b) is obtained, the rotation driving means of the roller may be controlled by a detection means (not shown). Or roller 1
An eccentric load may be applied to the motor to maintain a predetermined stop rotation angle position.

FIG. 4 shows another example of a structure in which the acting force between the leading end of the sheet and the peripheral surface of the switching roller increases the force for guiding the sheet in the desired direction when the roller stops and when the roller rotates. . FIG. 4A shows the position of the drive system of the switching roller when the roller is stopped. FIG. 7A shows the position of the switching roller 1 at that time. The switching roller 1 is rotatably supported by a free end of a lever 10 having a fulcrum at the center of the drive gear 11, and a driven gear 12 provided at the shaft end is provided with a drive gear 11.
It is driven by meshing with. Two stoppers 13 and 14 for regulating the movable range of the lever 10 are implanted in the side plate that supports the drive gear 11. Due to the own weight of the driven gear 12, the driven gear 12 is held at a position in contact with the stopper 14, and as a result, the switching roller 1 becomes (a ').
As shown in the figure, the sheet 4 conveyed from the upstream conveyance path at the branch point is held in a position where the space between the first conveyance path 2 and the upper guide plate is widened, and the sheet 4 smoothly moves toward the first conveyance path 2. Led to.

(B) and (b ') show the driving gear 1 respectively.
FIG. 3 is a diagram illustrating a driving system, a position of a lever, and a position of a switching roller when the first roller is driven. When the drive gear 11 rotates, the driven gear 12 is rotated by the engagement of both gears, and receives a moment to rotate counterclockwise around the fulcrum of the lever 10 in the figure, and the lever 10 comes into contact with the stopper 13. As a result, the switching roller 1 is displaced to a position where the path to the second transport path 3 is greatly opened as shown in FIG. Under the action of the switching roller 1, it is advantageously guided towards the second transport path 3.

In the embodiment shown in FIG. 5, the switching roller 1 is mounted with the rotating shaft 1b eccentric, and when the switching roller is stopped, the switching roller 1 has a center of gravity which coincides with the geometric center as shown in FIG. The sheet 4 is held at a position directly below the eccentric rotating shaft 1b, is largely separated from the upper guide plate of the first transport path 2, and smoothly guides the sheet 4 transported by the upstream transport roller 5 to the first transport path 2. I do.

When the transport roller 1 rotates, as shown in FIG. 2B, the transport roller 1 has a cylindrical shape whose outer peripheral surface is a circle shown by a broken line in the figure having a maximum radius from the eccentric rotating shaft 1b. The sheet rotates in a locus and reliably acts on the sheet 4 conveyed to the branch portion by the upstream conveying roller 5.
To the second transport path 3.

In another embodiment shown in FIG. 6, instead of decentering the rotating shaft of the switching roller 1, a weight 20 is attached to the tip of an arm fixed to the switching roller 1, and when the switching roller 1 stops, (a) As shown in FIG.
Is held at a position directly below the axis of the switching roller 1, and when the switching roller 1 is rotated, as shown in FIG. The sheet is rotated while drawing a trajectory, and the sheet can be smoothly and reliably guided to the first transport path when stopped and to the second transport path when rotated. As shown in FIG. 6 (a), it is still more effective if the switching roller is provided with a missing circle so that the leading edge of the sheet at the time of stop comes into contact with the sheet obliquely and slides.

In the embodiment shown in FIG. 7, the surface of the switching roller 1 has a relatively long hair 1
a is in the form of a brush in which the switching rollers 1
(A) As shown in the figure, the hair 1a hangs down like a hair so that the tip is directed downward, the space between the hair 1a and the upper guide plate of the first transport path 2 is largely opened, and the hair is transported by the upstream transport roller 5. The guided sheet 4 is smoothly guided toward the first transport path 2. When the switching roller 1 is rotated, the bristle 1a extends in the normal direction of the peripheral surface of the switching roller due to centrifugal force, and its tip becomes cylindrical with the axis of the switching roller 1 as the center, and the diameter of the switching roller substantially increases. Then, the sheet 4 conveyed from the upstream of the branch point exerts an action force toward the second conveyance path 3, and the sheet 4 is reliably guided to the second conveyance path 3. As shown, it is also effective to form a small ball at the tip of each hair.

By the way, in the transport path switching apparatus of the present invention, in which the switching roller is stopped when the sheet transport direction is switched to the first transport path, when the sheet is transported to the first transport path, the switching roller is simply a guide plate, a deflector plate. And the acting force between the front end of the seat and the front end of the seat is not effective in guiding the seat. Rather, the straight running force due to the stiffness of the seat is important.

Therefore, as shown in FIG. 8, the direction in which the first transport path 2 extends is set so as to be substantially in line with the upstream transport path at the branch point, in order to assist the transport by the rectilinear force due to the waist strength. If the direction of the second transport path 3 is arranged so as to be deflected with respect to the direction of the upstream transport path, when the first transport path is selected, the sheet travels straight with the strength of the waist of the sheet itself,
The switching roller 1 can be smoothly guided to the first transport path and prevented from erroneously entering the second transport path. When the second transport path is selected, the switching roller 1 rotates as shown in FIG. The sheet 4 can be reliably guided to the second transport path by the acting force between the sheet 4 and the leading end of the sheet 4.

Incidentally, even in an image forming apparatus such as a copying machine or a printer capable of performing double-sided recording as illustrated in FIG. 9, in normal image formation, single-sided image formation on only the front surface is overwhelmingly performed. In fact, the opportunity to guide the sheet from the branching section to the re-feeding path is extremely small as compared with the opportunity to guide the sheet to the transport path to the sheet discharging section outside the apparatus.

Therefore, if the second transport path that requires the rotation drive of the path switching roller when guiding the sheet is a transport path to the re-feeding path and the first transport path is a discharge path to the outside of the apparatus, The need for rotational drive of the switching rollers is limited to a minimum, further improving the life and reliability of the device.

[0034]

As described above, according to the present invention, the switching of the conveying direction at the branch point of the sheet conveying path is performed using the switching roller capable of high-speed switching, and only when the sheet is guided to one of the conveying paths. The switching roller is rotationally driven, and when the guide to the other transport path is performed, the switching is performed in a state where the switching roller is stopped. Therefore, regardless of the sheet interval, the switching of the sheet transport direction can be performed at high speed and reliably. This is effective in saving power consumption and improving life and reliability.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views illustrating a state where a switching roller is stopped and a state where a switching roller is driven, according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of another embodiment of the present invention.

FIGS. 3A and 3B are cross-sectional views each showing a configuration of still another embodiment of the present invention.

4 (a) shows the position of the roller support lever when the switching roller is stopped, FIG. 4 (a ') shows the position of the switching roller, and FIG. 4 (b) shows the driving of the switching roller. FIG. 6B is a side view showing the position of the lever at the time, and FIG.

FIGS. 5A and 5B are cross-sectional views illustrating a state where the switching roller is stopped and a state where the switching roller is driven, according to still another embodiment of the present invention.

FIGS. 6A and 6B are side views showing a state of the switching roller and the weight when the switching roller is stopped, and FIG. 6B is a state when the switching roller is driven, according to still another embodiment of the present invention.

FIGS. 7A and 7B are cross-sectional views illustrating a state where the switching roller is stopped and a state where the switching roller is driven, according to still another embodiment of the present invention.

FIGS. 8A and 8B are cross-sectional views illustrating an example of a desirable arrangement of a conveyance path of a sheet conveyance path branching portion to which the present invention is applied, wherein FIG. 8A illustrates a state when the switching roller is stopped, and FIG. .

FIG. 9 is a schematic diagram illustrating an overall arrangement of a sheet conveyance path of an image forming apparatus having a branch portion in the sheet conveyance path.

FIG. 10 is a cross-sectional view of an example of a conventional gate-type sheet conveyance path switching device.

FIG. 11 is a cross-sectional view of an example of a conventional sheet transport path switching device using a switching roller.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 switching roller 2 first transport path 3 second transport path 4 sheet 5 transport roller 10 lever 11 drive gear 12 driven gear 13, 14 stopper 20 weight

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Shibaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References Real opening Sho 64-18059 (JP, U) 63-183157 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65H 29/60

Claims (6)

(57) [Claims] A rotatable switching roller provided at a branch of a sheet transport path having a branch between a first transport path and a second transport path, wherein a rotatable switching roller is provided between a leading end of a conveyed sheet and a surface of the switching roller. In the sheet conveying path switching device for switching a sheet conveying path by an action force, the switching roller is rotatable only in one direction, and the switching of the leading edge of the conveyed sheet is performed in a state where the switching roller is stopped. The sheet is guided to the first conveyance path by the action force based on the angle of contact with the peripheral surface of the roller. When the switching roller is rotating, the sheet is guided between the peripheral surface of the rotating roller and the leading end of the sheet that contacts with the roller. A sheet conveyance path switching device, wherein a sheet is guided to a second conveyance path by an action force caused by engagement between the sheet conveyance path and the second conveyance path. 2. The switching roller according to claim 1, wherein the switching roller is provided with a guide assisting device that assists in guiding the sheet leading edge to the first conveyance path when the switching roller is stopped. Sheet conveyance path switching device. 3. A means for setting the stop position of the switching roller to a fixed rotation angle position, and transports the sheet between the leading end of the sheet and the peripheral surface of the switching roller at the stop position of the switching roller. 3. The sheet conveying path switching device according to claim 1, wherein an acting force for guiding the sheet to the path is increased. 4. As means for setting the stop position of the switching roller to a fixed rotation angle position, the position of the center of gravity of the switching roller is deviated from the center of rotation, and in the stopped state, the center of gravity is below the center of rotation by its own weight. The sheet conveying path switching device according to claim 3, wherein the sheet conveying path switching device stops at a coming position. 5. The sheet conveying path switching device according to claim 1, wherein the effective radius of the switching roller is larger than that at the time of stop due to the action of centrifugal force during rotation. 6. The apparatus according to claim 1, wherein the first transport path is arranged substantially in line with the transport path upstream of the branch point, and the second transport path is deflected with respect to the transport path upstream of the branch point. The sheet conveying path switching device according to claim 1, wherein a path is arranged.