JP2000309466A - Switchback device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deliver even curling sheet members in the downstream precisely on a switchback basis without causing no sheet jams, curling selvages and the like. SOLUTION: A switchback device 7 for image forming devices comprises a reversing tray 73 for storing introduced sheet members, a guide member 71 for guiding the sheet members or pressing them on the reversing tray 73 when they are fed from the reversing tray 73 in the direction opposite to the introduction direction, a guide member switching device 72 for switching over the guide member 71 between a sheet member introducing position and a sheet member pressing position relative to the reversing tray 73, and a sheet member feed device 74 for feeding the sheet members from the reversing tray 73 in the direction opposite to the introduction direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a laser printer, a facsimile, and the like, and more particularly to a switchback device of an image forming apparatus using an electrophotographic technique.

[0002]

2. Description of the Related Art FIG. 9 is a diagram showing a switchback device of a conventional image forming apparatus. The prior art will be described below with reference to FIG. The conventional switchback device 7 includes a reversing tray 73, a switchback roller 741, a switchback roller driving device (not shown), and a contact / separation arm 74.
2, an arm shaft 743, a contact / separation solenoid 744, a contact / separation arm biasing member 745, and a contact / separation spring 746, a hitting guide 751 and a hitting guide shaft 7.
52, a tapping solenoid 753 and a tapping guide urging member 75
Sheet member hitting device 75 comprising a pressing spring 4 and a hitting spring 755
It is composed of

Next, the operation of the conventional switchback device 7 will be described. First, in a state of waiting for the introduction of the sheet member, the rotation of the switchback roller 741 stops,
In addition, the hitting guide 751 is in a retracted state (shown by a virtual line) in a state of being retracted from the reversing tray 73.
Here, when the sheet member is conveyed from the upstream conveyance path 24, the conveyed sheet member is moved to the entrance roller pair 24.
The reversing tray 73 is caused to enter the reversing tray 73 by driving the first and second 242. The tip of the sheet member is the switchback roller 741
, The switchback roller 741 comes into contact with the sheet member on the reversing tray 73 and transmits the rotation drive (counterclockwise in the case of the angle in the figure) of the switchback roller 741 to move the sheet member to the right in the figure. In the direction. When the entire sheet member enters the switchback device 7, the striking solenoid 753 is turned on, and the striking spring 75
5 becomes a solid line state against the biasing force of
The sheet rotates around the hitting guide shaft 752 and hits the rear end portion of the sheet member by its own weight in the direction of the reversing tray 73 so that the sheet member follows the reversing tray 73. Subsequently, the switchback roller 741 changes the rotation direction to the opposite direction (clockwise in the case of the angle shown in the figure), and conveys the sheet member to the pair of discharge rollers 251 and 252 of the downstream conveyance path 25. Let it drain.

[0004]

However, according to such a conventional apparatus, since the image forming apparatus has the fixing device, the image forming apparatus has a fixing device, so that the sheet member after the sheet member is introduced from the upstream conveyance path 24 can be used. If the end (therefore, the leading end when the paper is conveyed toward the downstream conveyance path 25) is curled, the paper cannot be conveyed to the downstream conveyance path 25 accurately, and a paper jam or breakage of the sheet member ( The corner portion of the sheet member is broken in a triangular shape).

Further, the operation of hitting the rear end of the sheet member to the reversing tray 73 by the hitting guide 751 is performed to instantly convey the sheet member introduced from the upstream conveyance path 24 to the downstream conveyance path 25. This is a necessary operation, and the sheet member conveying device 74 is a configuration necessary for conveying the sheet member in the switchback device 7 and further changing the conveying direction. The mechanism for contacting and separating is also necessary when the sheet member is introduced into the switchback device 7 or when the sheet member is conveyed from the switchback device 7 to the downstream side. These components are described above. A complicated mechanism such as a mechanism for striking with simple operation and a mechanism for connecting and disconnecting the switchback roller of the sheet member transport device 74 Is required, it had become expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a switchback device having a simple structure that accurately switches back and conveys the sheet to a downstream side without causing a paper jam or breakage of the edge even when the sheet member is curled. That is.

[0007]

According to a first aspect of the present invention, there is provided a switchback device for an image forming apparatus, comprising: a reversing tray for accommodating a sheet member to be introduced; A guide member that presses and guides the sheet member to the reversing tray when the sheet member is transported from the reversing tray in a direction opposite to the introduction direction, and a state in which the guide member is introduced into the reversing tray and the sheet member is moved to the reversing tray. A switchback for an image forming apparatus, comprising: a guide member switching device that switches between a pressing state and a pressing state; and a sheet member conveying device that conveys a sheet member from a reversing tray in a direction opposite to the introduction direction. An apparatus is provided.

According to the above configuration, when the sheet member is conveyed from the reversing tray, the sheet member is pressed against the reversing tray by the guide member, and both sides of the sheet member are guided by the guiding member and the reversing tray. Even if it is curled, it is guided in the up-down direction, and is conveyed to the downstream conveyance path while straightening in the surface direction is straightened.

Further, after the sheet member is introduced into the reversing tray, the guide member is held down until the sheet member is conveyed from the reversing tray (claim 2). Therefore, the sheet member is introduced into the reversing tray. Thereafter, the sheet is pressed against the reversing tray by the guide member until the sheet is conveyed from the reversing tray, and both sides of the sheet member are guided by the guide member and the reversing tray.

Further, after the sheet member is introduced into the reversing tray, the guide member is set to the pressed state, and the guide member is switched from the pressed state to the introduced state until the next sheet member is introduced into the reversing tray ( After the sheet member is introduced into the reversing tray, the sheet member is pressed against the reversing tray by the guide member until the sheet member is conveyed from the reversing tray, and both sides of the sheet member are guided by the guide member and the reversing tray. The guide member is switched from the pressed state to the introduced state before the next sheet member is introduced into the reversing tray.

According to a fourth aspect of the present invention, there is provided a switchback device for an image forming apparatus, comprising: a reversing tray for accommodating a sheet member to be introduced; Device, the sheet member pressing and conveying device, a switchback roller,
A switchback roller contact / separation device that switches the switchback roller between a state where the sheet member is introduced into the reversing tray and a pressing state where the sheet member is pressed against the reversing tray; and a direction in which the sheet member is introduced from the reversing tray. A switchback roller driving device for transporting the sheet member in the reverse direction, and when the sheet member is introduced into the reversing tray and when the sheet member is transported from the reversing tray, the switchback roller contacting / separating device presses the switchback roller. There is provided a switchback device for an image forming apparatus, wherein the switchback device is in an attached state.

According to the above construction, when the sheet member is introduced into the reversing tray, the sheet member is pressed against the reversing tray by the switchback roller, and when the sheet member is conveyed from the reversing tray, the sheet member is pressed against the reversing tray by the switchback roller. And transported to a downstream transport path.

Further, when the sheet member is introduced into the reversing tray, the switchback roller is pressed, and
Since the switchback roller is kept pressed until the sheet member is conveyed from the reversing tray (claim 5),
The sheet member is pressed against the reversing tray by the switchback roller from when the sheet member is introduced into the reversing tray to when the sheet member is conveyed from the reversing tray, and both sides of the sheet member are guided and conveyed by the switchback roller and the reversing tray.

Further, when the sheet member is introduced into the reversing tray, the switchback roller is set in a pressed state,
The switchback roller is switched from the pressed state to the introduced state before the next sheet member is introduced into the reversing tray (claim 6), so that the sheet member is transported from the reversing tray after being introduced into the reversing tray. The sheet member is pressed down to the reversing tray by the guide member, and both sides of the sheet member are guided by the switchback roller and the reversing tray. The switchback roller is switched from the pressed state to the introduced state before the next sheet member is introduced into the reversing tray.

Further, the switchback roller presses the rear end of the sheet member against the reversing tray when the sheet member is introduced into the reversing tray (claim 7). Since the rear end is pressed against the reversing tray by the switchback roller, both sides of the sheet member are guided by the switchback roller and the reversing tray.

According to an eighth aspect of the present invention, there is provided a switchback device for an image forming apparatus, comprising: a reversing tray for accommodating a sheet member to be introduced; A guide member that presses and guides the sheet member to the reversing tray when the member is transported in a direction opposite to the introduction direction, and a pressing member that presses the guide member onto the reversing tray and presses the sheet member against the reversing tray. And a sheet member conveying device for conveying the sheet member from the reversing tray in a direction opposite to the introduction direction. Further, a predetermined interval in the width direction is provided on the lower surface of the guide member. An upper rib is formed on the upper surface of the reversing tray, and a lower rib is formed on the upper surface of the reversing tray at a predetermined interval in the width direction. At least once, the switchback device of the image forming apparatus, characterized by the pressed state a guide member by the guide member switching device is provided during a period from the introduction until conveyed in the reverse direction.

According to the above configuration, the sheet member is pressed against the reversing tray by the guide member at least once between the time when the sheet member is introduced into the reversing tray and the time when the sheet member is conveyed in the reverse direction. Even if it is, it is guided in the up-down direction, and the deflection in the plane direction is straightened.

Further, after the sheet member is introduced into the reversing tray, the guide member is held down until the sheet member is conveyed from the reversing tray (claim 9). Therefore, the sheet member is introduced into the reversing tray. Thereafter, the sheet is pressed against the reversing tray by the guide member until it is conveyed from the reversing tray, and even if the sheet member is curled, the sheet member is guided vertically for a long time, and straightening in the surface direction is straightened. Things.

Further, after the sheet member is introduced into the reversing tray, the guide member is set to the pressed state, and the guide member is switched from the pressed state to the introduced state until the next sheet member is introduced to the reversing tray ( Claim 10)
After the sheet member is introduced into the reversing tray, the sheet member is pressed against the reversing tray by the guide member until the next sheet member is introduced into the reversing tray. And straightening of the bending in the surface direction is straightened.

Further, since the upper ribs and the lower ribs are alternately formed in the width direction (claim 11), the sheet member is curled by the upper ribs of the guide member and the lower ribs of the reversing tray. Even if it is, the deflection in the plane direction is straightened.

Further, since the upper rib and the lower rib intersect in the vertical direction (claim 12), the sheet member is curled by the upper rib of the guide member and the lower rib of the reversing tray. This is also straightened by waving the bending in the surface direction.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining the operation of forming an image on both sides of a sheet member in an image forming apparatus employing an embodiment of the present invention. Hereinafter, description will be made with reference to FIG.

The sheet members fed one by one from the paper feed cassette 1 by the paper feed roller 11 pass through the conveying path 21, are adjusted in the leading end by the registration unit 3, stand by, and enter the image forming unit 4 at a predetermined timing. The sheet is conveyed, and the toner image formed by the image forming unit 4 is transferred to the first surface of the sheet member by the transfer device 45. The sheet member having the toner image transferred to the first surface is
The sheet is conveyed to the nip portion between the heat roller 51 and the pressure roller 52 of the fixing device 5 by the conveyance path 23, and the two rollers 5
1 and 52 hold the sheet member and heat it,
The surface toner image is fixed. Next, the sheet member on which the image is formed on the first surface is introduced into the switchback device 7 via the transport path 24 by the branching device 6, and is turned upside down. Thereafter, the transport direction is changed in the switchback device 7 and the transport is performed to the transport path 25. Subsequently, the sheet member on which the image has been formed on the first surface is again adjusted in its leading end by the registration unit 3 via the conveyance path 26 and waits, is conveyed to the image forming unit 4 at a predetermined timing, and is formed by the image forming unit 4. The transferred toner image is transferred by the transfer device 45 to the second surface (the back surface of the first surface) of the sheet member. The sheet member having the toner image transferred on the second surface is conveyed to the nip portion between the heat roller 51 and the pressure roller 52 of the fixing device 5 through the conveyance path 23, and is nipped by the two rollers 51 and 52 and heated. Thus, the toner image on the second surface is fixed. The sheet member on which images are formed on both sides passes through a paper discharge unit 8 by a branching device 6 and is discharged to a paper discharge tray 9.
Is discharged.

FIG. 2 is a diagram showing a configuration of a switchback device in the image forming apparatus to which the embodiment of the present invention is applied, and FIG. 3 is a perspective view of the switchback device. 3 will be described in detail.

The switchback device 7 includes an upper guide 71
1, a guide shaft 712, and a holding guide 71 having a guide arm 713 (functioning as a guiding member); and a holding guide switching device 72 (which functions as a guiding member switching device) including a holding solenoid 721 and a holding spring 722. ), The reversing tray 73, the switchback roller 741, and the switchback roller driving device 78.
And a contact / separation arm 742, an arm shaft 743, a contact / separation solenoid 744, a contact / separation arm urging member 745, and a contact / separation spring 746.

More specifically, the upper guide portion 7 of the holding guide 71
Reference numeral 11 denotes a sheet member introduced state in which the upper guide portion 711 is rotated by the press guide switching device 72 around the guide shaft 712, and is flipped up (shown in phantom lines in FIG. 1).
Then, a pressing state, which is a sheet member conveyance state (shown by a solid line in FIG. 2) in which the upper guide portion 711 is opposed to the sheet member conveyance surface 731 of the reversing tray 73 with an appropriate gap. The appropriate gap is such that one sheet member can pass comfortably between the upper guide portion 711 and the sheet member conveying surface 731. Even if the passing sheet member is curled, the next downstream side is suitable. The interval is such that the sheet member can be straightened in the surface direction (curl) until the sheet member is conveyed to the conveyance path 25, and is suitably about 1 mm to 5 mm.

As shown in FIG. 3, the surface of the upper guide portion 711 which presses the sheet member is parallel to the sheet member conveying direction at a predetermined interval in the width direction (perpendicular to the paper plane) in order to improve the sliding of the sheet member. Are provided with a plurality of upper ribs 713r.

Similarly, a plurality of lower ribs 733r are provided on the sheet conveying surface 731 (see FIG. 2) of the reversing tray 73 in the width direction at a predetermined interval in parallel with the sheet conveying direction in order to improve the sliding of the sheet. Is provided.

FIGS. 5A and 5B show details of the upper guide and the reversing tray. FIG. 5A shows a state in which the sheet member is pressed, and FIG. 5B shows the arrangement of the ribs. FIG. Hereinafter, the description will be continued with reference to FIG.

The width d1 of the upper rib 713r and the lower rib 7
Each of the widths d2 of 33r is formed to be approximately 0.5 mm to 4.0 mm, preferably 1.5 mm to 2.0 mm. The cross-section of the tip of the upper rib 713r and the lower rib 733r is R
And r = 0.25 mm to 2.0 mm, preferably r = 0.75 mm to 1.0 mm.

The upper rib 713r and the lower rib 733r are both formed at an interval of approximately 40 to 60 mm (preferably w1 = w2 = 50 mm) in the width direction (the horizontal direction in FIG. 5), and the upper rib 713r and the lower rib 733r are formed. Are alternately arranged.

The height h1 of the upper rib 713r and the height h2 of the lower rib 733r are both 5 mm, and the crossing range h3 in the vertical direction is 1.5 mm to 4.0 mm.
5 mm, preferably 2.5 mm to 3.5 mm. Thus, the upper rib 713r and the lower rib 733r
5 are arranged so as to intersect in the vertical direction.
As shown in (a), the upper rib 713r and the lower rib 73
The sheet member sandwiched between 3r is bent in the width direction to eliminate bending (curl).

The press guide switching device 72 includes a press solenoid 721 and a press spring 722. When the press solenoid 721 is OFF, the press spring 722 is in a contracted state, and the press spring 722 is moved to the upper guide portion 71.
The guide arm 713 is urged so that the sheet member 1 is turned around the guide shaft 712 to be in a state of entering the sheet member (shown by phantom lines in FIG. 1). Holding solenoid 7
When 21 is ON, the holding solenoid 721 pulls the guide arm 713 to rotate the upper guide 711 about the guide shaft 712 so as to face the sheet member conveying surface 731 of the reversing tray 73 with an appropriate gap. The sheet member is conveyed (shown by a solid line in FIG. 1).

The reversing tray 73 is provided on the sheet conveying surface 7.
31 and a sheet contact portion 732.
As described above, the lower ribs 733r are provided at appropriate intervals in the width direction on the sheet member conveying surface 731 so that the sheet member can be smoothly conveyed. Sheet member contact portion 73
2 is not indispensable in the switchback device 7 having the sheet member conveying device 74, but in the present embodiment, the sheet contact portion 732 is formed on the sheet member conveying surface 731 according to the size of the sheet member to be conveyed. The sheet member can be moved in the member conveyance direction (the left-right direction in FIG. 2), and the length from the surface of the sheet member contact portion 732 to the entrance / exit 714 of the sheet member is substantially the same as the length of the sheet member in the conveyance direction (exactly, Is slightly larger than the length of the sheet member in the conveyance direction), and is driven by the rack and pinion 733 and the stepping motor 734 based on the detection signal of the sheet member size or the setting information of the operator, thereby positioning the sheet contact portion 732. Is going.

The switchback roller 741 is an EPD
A material such as M, CR rubber, urethane rubber, or natural rubber, which is used as a feed roller or a transport roller in a normal image forming apparatus, may be used in a clockwise direction or a counterclockwise direction by a switchback roller driving device 78. Is also controlled to rotate, and conveys the sheet member.

Next, a mechanism relating to the contact / separation of the sheet member conveying device 74 with respect to the sheet member will be described. The switchback roller 741 is rotatable about an arm shaft 743 while being supported by the contact / separation arm 742, and can be switched between a contact state with the sheet member (shown by a solid line in FIG. 2) and a retracted state (shown by a virtual line in FIG. 2). Selectively positioned. The switchback roller 741 is normally positioned in the retracted state. At this time, since the contact / separation solenoid 744 is OFF, the contact / separation spring 7
46 urges the contact / separation arm 742 in a direction to retract the switchback roller 741 via the contact / separation arm urging member 745. When the sheet member on the reversing tray 73 is conveyed, the switchback roller 741 is in a contact state. At this time, when the contact / separation solenoid 744 is turned on, the contact / separation arm urging member 745 is attached to the contact / separation arm 742. The switch back roller 7
Reference numeral 41 contacts the sheet member by its own weight.

FIG. 4 is a diagram showing the operation of the switchback device 7, which will be described below with reference to FIG. First, in a state of waiting for the introduction of the sheet member, the switchback roller 741 has stopped rotating, and
The pressing guide 71 is in a state where the sheet member has been introduced by flipping the upper guide portion 711. When the sheet member is conveyed from the upstream conveyance path 24 here, the conveyed sheet member is moved into the pair of entrance rollers 241,
242 is driven into the switchback device 7. FIG. 4A shows a state in which the sheet member is introduced into the switchback device 7 as described above.

Next, when the leading end of the sheet member comes under the switchback roller 741, the movement of the contact / separation arm 742 causes the switchback roller 741 to move to the reversing tray 7.
2, by contacting the upper surface of the upper sheet member and transmitting the rotational driving of the switchback roller 741 (counterclockwise in the case of the angle shown in the figure), the sheet member is moved rightward in the figure, and the entire sheet member is switched to the switchback device 7. When it enters the holding guide 71, the holding guide switching device 72
As a result, a sheet member conveyance state in which the upper guide portion 711 is opposed to the reversing tray 73 with an appropriate gap is provided. FIG.
(B) shows that the entire sheet member enters the switchback device 7 and the upper guide portion 7 of the pressing guide 71 as described above.
11 shows a state in which the pressing guide switching device 72 is in the process of switching from the sheet member introduction state to the sheet member conveyance state.

Subsequently, the switchback roller 741 changes the rotation direction to the opposite direction (clockwise in the case of the angle shown in the figure), and moves the sheet member to the discharge roller pair 25 of the downstream side transport path 25.
1, and is discharged from the switchback device 7. FIG. 4C shows a state in which the sheet member is being discharged from the switchback device 7 as described above.

As soon as the front end (rear end at the time of introduction) of the sheet member whose conveyance direction is reversed is transferred to the pair of discharge rollers 251 and 252 of the downstream conveyance path 25, the holding solenoid 721 is turned off, and FIG. As shown in
The upper guide portion 711 is in a state where the jumped-up sheet member is introduced, and prepares for the introduction of the next sheet member.

FIGS. 6 and 7 are diagrams showing the configuration of a switchback device in an image forming apparatus according to another embodiment of the present invention, and FIG. 8 is a diagram showing the operation in another embodiment. Another embodiment of the present invention will be described in detail with reference to FIGS. The same components as those in the above-described embodiment are denoted by the same reference numerals.

The switchback device 7 includes a sheet member pressing and conveying device 77 and a reversing tray 73. The sheet member pressing / conveying device 77 includes a switchback roller driving device 78 and a switchback roller contact / separation device 7.
9. The switchback roller driving device 78 drives the switchback roller 761. The switchback roller contact / separation device 79 includes a switchback roller 761, a pressing arm 762, and an arm shaft 76.
3, a pressing solenoid 774, a pressing arm urging member 775, and a pressing spring 776.

Note that the switchback roller 761 is
A material such as PDM, CR rubber, urethane rubber, or natural rubber, which is used as a normal feed roller or a transport roller, may be used, and is controlled by a switchback roller driving device 78 so as to stop or rotate clockwise as shown in the figure. Then, the sheet member is conveyed rightward or leftward in FIG.

A mechanism relating to the pressing of the sheet member pressing / conveying device 77 to the sheet member, that is, the switchback roller contact / separation device 79 will be described. The switchback roller 761 is supported by the pressing arm 762, and the switchback roller 761 and the pressing arm 7
Reference numeral 62 is provided above the left side of the reversing tray 73.
The switchback roller 761 is connected to the arm shaft 763.
, And selectively positioned in a pressed state (contact state) with respect to the sheet member and a sheet member introduced state (separated state). The switchback roller 761 is normally positioned in the sheet member introduction state. At this time, since the pressing solenoid 774 is OFF,
A pressing spring 776 urges the pressing arm 762 in a direction to retract the switchback roller 761 via a pressing arm urging member 775. When the switchback roller 761 performs the pressing operation, the pressing arm 774 is turned on to release the pressing of the pressing arm urging member 765 against the pressing arm 762, and as a result, the switchback roller 761 has its own weight. Of the sheet member to be introduced is pressed against the sheet member conveying surface 731 of the reversing tray 73.

The reversing tray 73 has a sheet member conveying surface 731.
And a sheet member contact portion 732. The sheet member conveying surface 731 is provided with lower ribs 733r (see FIGS. 3 and 5) at predetermined intervals in the width direction (perpendicular to the paper surface), so that the sheet member can be smoothly conveyed. The sheet member contact portion 732 is not essential in the switchback device 7 having the sheet member pressing / conveying device 77, but in the present embodiment, the sheet member contact portion 73 is used.
Numeral 2 is movable in the sheet member conveying direction (the left-right direction in FIG. 6) on the sheet member conveying surface 731 according to the size of the sheet member to be conveyed.
The position of the sheet contact portion 732 is determined so that the length from the surface of the sheet member to the entrance / exit 714 of the sheet member is substantially the same as the length of the sheet member in the conveyance direction. By driving with a rack and pinion 733 and a stepping motor 734 based on the
Is positioned.

The operation of the switchback device 7 will be described below with reference to FIG. First, in a state of waiting for the introduction of the sheet member, the rotation of the switchback roller 761 is stopped and is retracted from the reversing tray 73. When the sheet member is conveyed from the upstream conveyance path 24 here, the conveyed sheet member is moved into the pair of entrance rollers 241,
The switch 242 is driven to enter the switchback device 7. FIG. 8A shows a state in which the sheet member enters the switchback device 7 as described above.

Next, at the timing when the entire sheet member enters the switchback device 7, the movement of the pressing arm 762 causes the switchback roller 761 to come into contact with the rear end portion of the entering sheet member, thereby causing the reverse tray 73 to move. And is rotated counterclockwise to move the sheet member rightward. The timing at which the switchback roller 761 strikes the sheet member is
Detecting means (not shown) such as a photo sensor is provided near the entrance 714 of the switchback device 7.
The predetermined time after the passage of the rear end of the sheet member is detected by the detection means. FIG. 8 (b) is as described above.
Until the entire sheet member enters the switchback device 7 and presses the rear end of the sheet member, which has entered by the sheet member pressing / conveying device 77 (see FIG. 6), against the sheet member conveying surface 731 of the reversing tray 73. Is shown.

Subsequently, when the entering sheet member is pressed against the sheet member conveying surface 731 of the reversing tray 73, the switchback roller 761 rotates (rotates clockwise in the case of the angle shown in the drawing) and moves the sheet member downstream. The sheet is conveyed to the pair of discharge rollers 251 and 252 in the side conveyance path 25. FIG.
(C) shows a state in which the sheet member is conveyed on the reversing tray 73 by the switchback roller 761 and conveyed to the downstream conveying path 25 as described above.

As described above, the leading end of the sheet member in which the sheet member carrying direction is reversed (the rear end in the carrying direction at the time of introduction).
Is transported to the discharge roller pair 251 and 252 of the downstream transport path 25, and the leading end of the next sheet member is
Before entering the inside, the pressing solenoid 744 is
The state becomes FF, and the sheet member pressing and conveying device 77 is in a retracted state. FIG. 8D illustrates a state in which the first sheet member is discharged as described above, and the sheet member pressing / conveying device 77 is used.
(See FIG. 6) shows a state in which the sheet member is in a retracted state and the next sheet member enters.

Thereafter, by repeating the same operation, the sheet members entering the switchback device 7 can be continuously switched back one by one.

As described above, other embodiments have been described in detail.
According to another embodiment, as shown in FIG. 7, by rotating the switchback roller 761 in the clockwise direction, the sheet member is moved to the downstream side of the conveying roller pair 251, 252.
, The switchback roller 761 can be brought into the introduced state in preparation for the introduction of the next sheet member, so that the time required for image formation can be reduced as a whole.

In the above embodiment, the sheet member means all sheets on which an image can be formed, such as a sheet for image formation, an OHP sheet, a tracing paper, a color material, and the like.

In the above embodiment, after the first surface, the second surface
Although the image forming apparatus of the type in which an image is formed on the surface (the surface opposite to the first surface) has been described as an example, the image forming apparatus may be of a type in which a so-called composite image formation in which image formation is performed a plurality of times on the first surface.

In the above embodiment, the reversing tray 73
When the sheet member is introduced, the switchback roller 741 or 761 is rotated counterclockwise to move the sheet member to the sheet member contact portion 732 in the right direction. The example in which the sheet member is conveyed while being rotated clockwise in the direction is illustrated. However, when the sheet member is introduced into the reversing tray 73, the rotation of the switchback roller 741 or 761 is stopped and the sheet member is turned right by inertia. It may be configured to approach the sheet member contact portion 732 in the direction.

In the above-described embodiment, the pressing member 71 presses the sheet member when the sheet member is introduced into the reversing tray 73. However, instead of this, the front end of the sheet member is the switchback roller 741. When the sheet reaches the bottom or the rear end of the sheet member
When passing through 41 and 242, the sheet member may be pressed.

In the above embodiment, after the sheet member is introduced into the reversing tray 73, the pressing guide 71 (guide member) is pressed down until it is conveyed in the reverse direction from the reversing tray 73 and reaches the downstream conveying device. Alternatively, after the sheet member is introduced into the reversing tray 73, the pressing guide 71 (at least once) is conveyed from the reversing tray 73 in the reverse direction and reaches the downstream conveying device. It is also possible to set the guide member) in a pressed state. Even in this case, even if the sheet member is curled, the sheet member can be guided in the up-down direction and straightened in the surface direction.

[0057]

As described in detail above, claim 1 of the present invention
According to the switchback device of the image forming apparatus, in the switchback device, the sheet member to be introduced is stored, and the sheet member is pressed against the reverse tray when the sheet member is transported from the reverse tray in a direction opposite to the introduction direction. Guide member, a guide member switching device for switching the guide member between a state where the sheet member is introduced into the reversing tray and a state where the sheet member is pressed onto the reversing tray, and a state where the sheet member is introduced from the reversing tray. And a sheet member conveying device that conveys the sheet in a direction opposite to the direction.

According to the above configuration, when the sheet member is conveyed from the reversing tray, the sheet member is pressed against the reversing tray by the guide member, and both sides of the sheet member are guided by the guiding member and the reversing tray. Even if it is curled, it is guided in the up-down direction, and is conveyed to the downstream conveyance path while straightening in the surface direction is straightened. In addition, it is possible to reduce problems such as a paper jam and breakage of the sheet member that have occurred around the switchback device due to the curl of the sheet member.

Further, after the sheet member is introduced into the reversing tray, the guide member is held down until the sheet member is conveyed from the reversing tray (claim 2). Therefore, the sheet member is introduced into the reversing tray. Thereafter, the sheet is pressed against the reversing tray by the guide member until the sheet is conveyed from the reversing tray, and both sides of the sheet member are guided by the guide member and the reversing tray. As described above, by continuously setting the guide member in the pressed state, the operation of the guide member is simplified, and by setting the guide member in the pressed state for a long time, the curl correction effect of the sheet member is reduced. It will increase.

Further, after the sheet member is introduced into the reversing tray, the guide member is set to the pressed state, and the guide member is switched from the pressed state to the introduced state until the next sheet member is introduced to the reversing tray ( After the sheet member is introduced into the reversing tray, the guide member presses the sheet member against the reversing tray, and the guide member and the reversing tray guide both sides of the sheet member. The guide member is switched from the pressed state to the introduced state before the next sheet member is introduced into the reversing tray. In this way, by continuously setting the guide member to the pressing state,
The operation of the guide member is extremely simplified, and the curl correction effect of the sheet member is increased by keeping the guide member in a pressed state for a long time.

According to a fourth aspect of the present invention, there is provided a switchback device for an image forming apparatus, comprising: a reversing tray for accommodating a sheet member to be introduced; Device, the sheet member pressing and conveying device, a switchback roller,
A switchback roller contact / separation device that switches the switchback roller between a state where the sheet member is introduced into the reversing tray and a pressing state where the sheet member is pressed against the reversing tray; and a direction in which the sheet member is introduced from the reversing tray. A switchback roller driving device for transporting the sheet member in the reverse direction, and when the sheet member is introduced into the reversing tray and when the sheet member is transported from the reversing tray, the switchback roller contacting / separating device presses the switchback roller. There is provided a switchback device for an image forming apparatus, wherein the switchback device is in an attached state.

According to the above construction, when the sheet member is introduced into the reversing tray, the sheet member is pressed against the reversing tray by the switchback roller, and when the sheet member is conveyed from the reversing tray, the sheet member is pressed against the reversing tray by the switchback roller. And transported to a downstream transport path. As described above, since the sheet member is directly pressed against the reversing tray by the switchback roller, the sheet member can be reliably transported to the downstream transport path. In addition, it is possible to reduce problems such as a paper jam and breakage of the sheet member that have occurred around the switchback device due to the curl of the sheet member.

Further, when the sheet member is introduced into the reversing tray, the switchback roller is pressed down,
Since the switchback roller is kept pressed until the sheet member is conveyed from the reversing tray (claim 5),
The sheet member is pressed against the reversing tray by the switchback roller from when the sheet member is introduced into the reversing tray to when the sheet member is conveyed from the reversing tray, and both sides of the sheet member are guided by the switchback roller and the reversing tray. As described above, since the sheet member is directly pressed against the reversing tray by the switchback roller for a long time, the sheet member can be reliably transported to the downstream transport path, and the operation of the switchback roller can be easily performed. it can.

Further, when the sheet member is introduced into the reversing tray, the switchback roller is pressed down,
The switchback roller is switched from the pressed state to the introduced state before the next sheet member is introduced into the reversing tray (claim 6), so that the sheet member is transported from the reversing tray after being introduced into the reversing tray. The sheet member is pressed against the reversing tray by the switchback roller until both sides of the sheet member are guided by the switchback roller and the reversing tray. The switchback roller is switched from the pressed state to the introduced state before the next sheet member is introduced into the reversing tray. in this way,
Since the sheet member is directly pressed against the reversing tray by the switchback roller for a long time, the sheet member can be reliably transported to the downstream transport path, and the operation of the switchback roller can be performed extremely easily.

Further, the switchback roller presses the rear end of the sheet member against the reversing tray when the sheet member is introduced into the reversing tray (claim 7). Since the rear end is pressed against the reversing tray by the switchback roller, both surfaces of the sheet member are guided by the switchback roller and the reversing tray, thereby preventing paper jams and breaks in the edges.

According to an eighth aspect of the present invention, there is provided a switchback device for an image forming apparatus, comprising: a reversing tray for accommodating a sheet member to be introduced; A guide member that presses and guides the sheet member to the reversing tray when the member is transported in a direction opposite to the introduction direction, and a pressing member that presses the guide member onto the reversing tray and presses the sheet member against the reversing tray. And a sheet member conveying device for conveying the sheet member from the reversing tray in a direction opposite to the introduction direction. Further, a predetermined interval in the width direction is provided on the lower surface of the guide member. An upper rib is formed on the upper surface of the reversing tray, and a lower rib is formed on the upper surface of the reversing tray at a predetermined interval in the width direction. At least once, the switchback device of the image forming apparatus, characterized by the pressed state a guide member by the guide member switching device is provided during a period from the introduction until conveyed in the reverse direction.

According to the above arrangement, the sheet member is pressed against the reversing tray by the guide member at least once between the time when the sheet member is introduced into the reversing tray and the time when the sheet member is conveyed in the reverse direction. Even in this case, the vertical direction is guided by the upper and lower ribs, and the bending in the surface direction is straightened. In addition, it is possible to reduce problems such as a paper jam and breakage of the sheet member that have occurred around the switchback device due to the curl of the sheet member.

Further, after the sheet member is introduced into the reversing tray, the guide member is held down until the sheet member is conveyed from the reversing tray (claim 9), so that the sheet member is introduced into the reversing tray. From time to time when the sheet is conveyed from the reversing tray, the sheet is pressed against the reversing tray by the guide member, and even if the sheet member is curled, the sheet member is guided vertically for a long time, and the deflection in the surface direction is straightened. Things. As described above, by continuously setting the guide member in the pressed state, the control for operating the guide member is simplified, and by setting the guide member in the pressed state for a long time, the curl correcting effect of the sheet member is improved. Is increased.

Further, after the sheet member is introduced into the reversing tray, the guide member is set to the pressed state, and the guide member is switched from the pressed state to the introduced state until the next sheet member is introduced to the reversing tray ( Claim 10)
The sheet member is pressed against the reversing tray by the guide member from the time the sheet member is introduced to the reversing tray to the time the next sheet member is introduced into the reversing tray. And straightening of the bending in the surface direction is straightened. As described above, by continuously pressing the guide member, the operation of the guide member becomes extremely simple, and by keeping the guide member pressed for a long time, the curl correcting effect of the sheet member is reduced. It will increase. Since the guide member is switched from the pressed state to the introduced state before the next sheet member is introduced into the reversing tray, the control for operating the guide member is extremely simplified.

Further, since the upper ribs and the lower ribs are formed alternately in the width direction (claim 11), the sheet member is curled by the upper ribs of the guide member and the lower ribs of the reversing tray. Even if it is, the deflection in the plane direction is straightened.

Further, since the upper rib and the lower rib intersect in the vertical direction (claim 12), the sheet member is curled by the upper rib of the guide member and the lower rib of the reversing tray. This is also straightened by waving the bending in the surface direction.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a switchback device of the present invention.

FIG. 2 is a diagram illustrating a switchback device of the present invention.

FIG. 3 is a perspective view illustrating a switchback device of the present invention.

FIG. 4 is a schematic diagram showing the operation of the switchback device of the present invention.

5A and 5B are diagrams illustrating details of an upper guide portion and a reversing tray, wherein FIG. 5A illustrates a state in which a sheet member is pressed, and FIG. is there.

FIG. 6 is a diagram illustrating a switchback device according to another embodiment.

FIG. 7 is a diagram illustrating a switchback device according to another embodiment.

FIG. 8 is a schematic diagram illustrating the operation of a switchback device according to another embodiment.

FIG. 9 is a schematic diagram of a conventional switchback device.

[Description of Signs] 7 Switchback device 71 Pressing guide (guide member) 72 Pressing guide switching device (Guide member switching device) 73 Reversing tray 74 Sheet member transport device 77 Sheet member pressing transport device 78 Switchback roller driving device 79 Switch Back roller contact / separation device 713r Upper rib 733r Lower rib 761 Switch back roller

Continuing from the front page (72) Inventor Hidemasa Kizen 1-2-28 Tamazo, Chuo-ku, Osaka City Inside Kyocera Mita Corporation (72) Inventor Yasunori Ueno 1-2-28 Tamazo, Chuo-ku, Osaka City Kyocera Mita Corporation (72) Inventor Hiroshi Kusumoto 1-2-28 Tamazo, Chuo-ku, Osaka-shi F-term in Kyocera Mita Corporation (reference) 2H072 CA01 FA01 JA02 3F053 BA03 BA12 LA02 LA05 LA07 LB01 3F100 AA02 BA12 BA14 CA12 CA15 EA02

Claims (12)

[Claims] 1. A switchback device for an image forming apparatus, comprising: a reversing tray for accommodating a sheet member to be introduced; and a sheet member pressed onto the reversing tray when the sheet member is conveyed from the reversing tray in a direction opposite to the introduction direction. A guide member for attaching and guiding the sheet member; a guide member switching device for switching the guide member between a state where the sheet member is introduced into the reversing tray and a state where the sheet member is pressed against the reversing tray; A switchback device for an image forming apparatus, comprising: a sheet member conveying device that conveys a sheet in a direction opposite to an introduction direction. 2. The switchback of the image forming apparatus according to claim 1, wherein after the sheet member is introduced into the reversing tray, the guide member is kept pressed until the sheet member is conveyed from the reversing tray. apparatus. 3. After the sheet member is introduced into the reversing tray, the guide member is set to a pressing state, and the guide member is switched from the pressing state to the introducing state until the next sheet member is introduced into the reversing tray. The switchback device for an image forming apparatus according to claim 1, wherein: 4. A switchback device for an image forming apparatus, comprising: a reversing tray for accommodating a sheet member to be introduced; and a sheet member pressing and conveying device, wherein the sheet member pressing and conveying device includes a switchback roller and a switchback roller. A switchback roller contacting / separating device that switches the switchback roller between a state where the sheet member is introduced into the reversing tray and a state where the sheet member is pressed against the reversing tray, and a direction in which the sheet member is introduced from the reversing tray. A switchback roller driving device that conveys the sheet member in the reverse direction, and when the sheet member is introduced into the reversing tray, and when the sheet member is conveyed from the reversing tray, by the switchback roller contact / separation device,
A switchback device for an image forming apparatus, wherein a switchback roller is pressed. 5. The switchback roller is pressed when the sheet member is introduced into the reversing tray, and the switchback roller is pressed until the sheet member is conveyed from the reversing tray. Item 5. A switchback device for an image forming apparatus according to Item 4. 6. A switchback roller is set in a pressing state when the sheet member is introduced into the reversing tray, and the switchback roller is switched from the pressing state to the introducing state until the next sheet member is introduced into the reversing tray. 5. The switchback device for an image forming apparatus according to claim 4, wherein: 7. The switchback device for an image forming apparatus according to claim 4, wherein said switchback roller presses a rear end of the sheet member against the reversing tray when the sheet member is introduced into the reversing tray. 8. A switchback device of an image forming apparatus, comprising: a reversing tray for accommodating a sheet member to be introduced; and a sheet member pressed onto the reversing tray when the sheet member is conveyed from the reversing tray in a direction opposite to the introduction direction. A guide member for attaching and guiding the sheet member; a guide member switching device for switching the guide member between a state where the sheet member is introduced into the reversing tray and a state where the sheet member is pressed against the reversing tray; A sheet member conveying device that conveys the sheet in a direction opposite to the introduction direction, and upper ribs are formed on the lower surface of the guide member at predetermined intervals in the width direction, and are formed on the upper surface of the reversing tray in the width direction. A lower rib is formed with an interval, and the guide member has at least one between a time when the sheet member is introduced into the reversing tray and a time when the sheet member is conveyed in the reverse direction. Switchback device of an image forming apparatus, characterized in that the pressed state a guide member by the guide member switching device. 9. The switchback of the image forming apparatus according to claim 8, wherein after the sheet member is introduced into the reversing tray, the guide member is held down until the sheet member is conveyed from the reversing tray. apparatus. 10. After the sheet member is introduced into the reversing tray, the guide member is set to a pressed state, and the guide member is switched from the pressed state to the introduced state until the next sheet member is introduced to the reversing tray. 9. The switchback device for an image forming apparatus according to claim 8, wherein: 11. The switchback device for an image forming apparatus according to claim 8, wherein said upper ribs and lower ribs are formed alternately in a width direction. 12. The switchback device for an image forming apparatus according to claim 11, wherein said upper rib and said lower rib intersect in a vertical direction.