JP3257712B2 - Transport path switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a printer, a copier,
Conveys (feeds) the conveyance path of an image forming apparatus such as a facsimile
The present invention relates to a transport path switching device that switches the transport direction of a sheet to be transported.

[0002]

2. Description of the Related Art Image forming apparatuses such as printers and copiers are
Increasing the speed of image processing tends to be further promoted in the future. In addition, from the viewpoint of resource protection, which has been increasing in recent years, image forming tends to be mainly performed by double-sided printing in which images are formed on both sides of a sheet (transfer paper).

In order to perform the double-sided printing, it is necessary to reverse the sheet on which an image is formed on one side and send it to the image forming unit again. Therefore, a conveying path for switching the conveying direction of the sheet is provided in the conveying path of the image forming apparatus. A switching device is required. Also, even when forming an image on only one side,
When sorting and discharging the sheet after transferring the image, a transport path switching device is required.

Therefore, a conventional image forming apparatus or the like includes a pair of rotatable branch claws 72, as shown in FIG.
By setting the position of 73 to the position shown in FIG. 54A, the sheet P conveyed in the direction indicated by the arrow by the conveying roller pair 76 can be moved straight to the conveying path provided with the conveying roller pair 75, or the solenoid can be used. By switching the branch pawl 72 to the position shown in FIG. 54B by a driving means such as the one shown in FIG. Is switched to the position shown in FIG. 54C, the sheet P can be selectively guided to the transport path provided with the lower transport roller pair 77 in the figure, and the sheet P can be transported to a desired transport path. There is one equipped with such a branch claw type transfer path switching device.

[0005] Further, as a transport path switching device, there has been proposed a device in which a transport path is switched by a method using air suction, as described in, for example, JP-A-60-52455.

[0006]

In recent years, OA devices such as printers and copiers have been increasingly multifunctional due to the addition of double-sided image formation, sorting, stacking mechanisms, and the like. In order to increase the number of prints without changing the image forming process speed, there is a demand for a technique for reducing the interval between sheets to be fed.

However, in response to such a demand, the conventional paper feed path switching device using the branch claw system cannot switch the sheet at a very high speed because the sheet switching speed is determined by the response speed of the branch claw. Could not respond to Further, even when high-speed switching of the transport path is not necessary, in the case of the branch claw method, a load is generally applied to the sheet, so that the sheet is easily damaged, and a jam or the like is likely to occur. It was easy.

On the other hand, in the case of the suction system using air, the transfer path can be switched at a high speed. However, since a suction device is required, the size of the device is increased and the cost is increased. In addition, there is a disadvantage that noise is generated, which is not very practical.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and even if a sheet is conveyed on a conveying path at a very small sheet interval in response to an increase in the speed of an apparatus, each conveying for the purpose is performed. An object of the present invention is to realize a device which can be reliably sent to a road at low cost. It is another object of the present invention to make the mechanism for switching the transport path compact with as few components as possible.

Further, when a sheet is conveyed to a target conveying path, the image transferred on the surface of the sheet is not rubbed to prevent the image quality from deteriorating. Another object of the present invention is to prevent the sheet from being buckled when the sheet is conveyed.

Further, when it is possible to switch the conveyance of a sheet to three or more conveyance paths or to discharge the sheet to a discharge tray, the sheet is reliably conveyed to the discharge tray without being conveyed to another conveyance path. It is also intended to be discharged. It is another object of the present invention to stably switch the transport path without applying a load to the sheet or damaging the sheet.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a feed roller pair for feeding a sheet and an extension of a sheet passing through a nip of the feed roller pair in a sheet feeding direction. Switching roller or switching bell that can rotate forward and reverse
And a preparative, while the switch the conveying direction of the sheet which is fed by the feeding roller pair by changing the rotational direction of the switching roller or switching belt, the upper
The transport direction is switched by the switching roller or switching belt.
First rotating in accordance with each transport direction of the replaced sheet
And the second driven roller as the switching roller or the switching belt.
Switching roller or switching bell
To have combined transport force to the preparative, and the first and second driven
Roller is separated from the above-mentioned switching roller or switching belt.
Driven roller separating means, and
Above the conveyance path side selected by the rotation direction of the replacement belt
The first or the first roller in contact with the switching roller or the switching belt;
Is the second driven roller, and the sheet leading end is the first or second
In contact with the above-mentioned switching roller or switching belt of the driven roller
After passing through the nip, the driven roller
The transport path switching device is configured to be separated from the switching roller or the switching belt .

[0013]

[0014]

[0015]

A switching unit retracting means for retracting the switching roller or the switching belt from a position at which the sheet conveying direction can be switched is provided, and a feeding roller is provided when the switching roller or the switching belt is retracted by the switching unit retracting means. It is preferable to provide a third transport path in which the sheet fed by the pair is transported linearly.

The switching section retreating means is means for retreating the switching roller or the switching belt to the lower side with respect to the third transport path. At the retreat position, the switching roller or the switching belt is supplied by the pair of feeding rollers. The sheet may be rotated or rotated in a direction in which the sheet comes in contact with the sheet to be conveyed.

The switching unit retracting means switches a switching roller or a switching belt between a retracted position and a sheet conveying direction in conjunction with opening and closing of a sheet discharge tray on which sheets discharged through the third conveying path are placed. It is good to be a means to move to a possible position .

Further, the sheet passing through the nip of the feed roller pair
A plurality of switching rollers or switching belts may be provided on the extension of the feeding direction of the sheet, so that the sheet fed by the feeding roller pair can be branched to different transport paths in three or more directions .

[0020] Furthermore, of disposed near the branch point of the conveying path
The sheet conveyed along the conveyance path
A switching roller pair for conveying while clamping, integrally with the first rotary drive means for rotating the direction of conveying while pinching the sheet conveyed on the conveying path the rollers of the switching roller pair, the entire switching roller pair The roller being parallel to the roller axis of the switching roller pair and being furthest from the pair of rollers.
Each outermost part is located on the same outer peripheral line during rotation.
Second rotation driving means for rotating in both the forward and reverse directions about a rotation shaft provided at the center of rotation provided by the rotation path.
The first direction in which the conveyed sheet is sandwiched between the rollers of the switching roller pair and conveyed, and the second rotation driving means
Above the rollers by the forward rotation of the entire switching roller pair with
The second direction in which the sheet is guided by the forward rotation outer periphery formed by the rotation locus of the outermost peripheral portion and the reverse rotation of the entire switching roller pair by the second rotation driving means causes the outermost rotation of each roller. Perimeter
The conveyance direction of the sheet conveyed on the conveyance path may be switched between a third direction for guiding the sheet on the reverse rotation outer periphery formed by the rotation locus of the unit .

[0021]

Further , in the above-described transport path switching device, it is effective to perform a transport path switching operation for switching the transport direction of the next sheet before the rear end of the sheet passes through the pair of switching rollers .

[0023]

According to the transport path switching device configured as described above,
By contacting the leading edge of the sheet fed by the feed roller pair with the switching roller or the switching belt , the sheet can be guided to the target conveyance path according to the rotation direction of the switching roller or the switching belt. Roller or
Since the sheet conveyance direction can be instantaneously switched by a simple operation of simply switching the rotation direction of the switching belt , even if the sheet is conveyed at a very small sheet interval on the conveyance path, the conveyance path is switched. Can be performed reliably.

[0024]

[0025]

[0026]

[0027]

Further, there is provided a driven roller separating means for separating the first and second driven rollers from the switching roller or the switching belt, and the conveying path side selected by the rotating direction of the switching roller or the rotating direction of the switching belt. First or second
Of the driven roller, the leading edge of the sheet above switching of the driven roller
Since the sheet is separated from the switching roller or the switching belt by the driven roller separating means after passing through the nip in contact with the switching roller or the switching belt , the rotation or rotation direction of the sheet while passing the nip of the switching roller or the switching belt is changed. Even if the sheet is reversed, it does not hinder the sheet conveyance, so even if the sheet is continuously fed at a very small sheet interval as close to zero as possible, the conveyance direction can be switched earlier. Switching of sheet conveyance can be reliably performed.

Further, if a switching section retreating means for retreating the switching roller or the switching belt is provided and a third transport path is provided, the switching roller or the switching belt is retreated by the switching section retreating means, so that the feeding roller pair is retracted. Can be linearly conveyed to the third conveyance path.

The switching unit retracting means is means for retracting the switching roller or the switching belt downward with respect to the third conveyance path, and rotates in a direction in which the sheet comes into contact with the sheet at the retraction position to assist the conveyance. Or if you rotate it,
When the switching roller or the switching belt conveys the sheet to the third conveyance path, they can function more effectively.

The switching unit retracting means switches a switching roller or a switching belt between a retracted position and a sheet conveying direction in conjunction with opening and closing of a sheet discharge tray on which sheets discharged through the third conveying path are placed. If the means is moved to a possible position, the switching roller or the switching belt is moved to the retreat position in conjunction with the opening of the sheet discharge tray, so that the transport path can be switched reliably without error.

[0032]

Also, a sheet passing through the nip of the feed roller pair
A plurality of switching rollers or switching belts are provided on the extension line in the feeding direction of, and the combination of their rotation directions is changed.
If the sheet can be branched into three or more different conveyance paths, the sheet can be selectively switched and conveyed to a conveyance path one number larger than the number of switching rollers or switching belts.

[0034]

[0035]

Further, a pair of switching rollers is disposed near the branch point of the conveying path, and first rotation driving means for rotating each roller in a conveying direction while holding the sheet between the rollers, and the pair of switching rollers. A second rotation driving means for integrally rotating the switching roller pair in both the forward and reverse directions about a rotation axis parallel to the roller axis of the switching roller pair; If you rotate the rollers,
The sheet conveyed in the conveying path is conveyed in the first direction while being sandwiched between the rollers, and when the entire switching roller pair is integrally rotated forward by the second rotation driving means, the sheet is rotated by the forward rotation outer periphery. The sheet is guided in the second direction, and when the entire switching roller pair is integrally and reversely rotated, the sheet is guided in the third direction by the reverse rotation outer circumference.

[0037] Then, the sheet is so guided by the switching roller pair in three directions described above are conveyed it stably without or damaged when passing through the branch point
You.

[0038]

In each of the above-described transport path switching devices, if the transport path switching operation for switching the transport direction of the next sheet is performed before the trailing end of the sheet passes through the pair of switching rollers , the preceding sheet can be switched. Can be switched without waiting for the sheet to pass through the pair of switching rollers, so that the direction of conveyance of the next sheet to be conveyed can be quickly changed, and the sheet interval is extremely small. Also, the sheet can be reliably sent to each of the target conveying paths.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. First, the embodiment of the present invention will be described with reference to FIG.
Prior to the description with reference to FIG.
FIG. 2 shows an example of a laser printer to which a mounting device is attached.
1 and FIGS. 3 to 3 show the prerequisite technology of the transfer path switching device of FIG.
This will be described with reference to FIG. The laser printer shown in FIG.
And a paper feed unit 3 are integrally incorporated in a table 5 and connected, and a paper discharge unit 4 is mounted on an upper portion.

When the image forming process is started, the photosensitive drum 8 provided in the printer main body 1 is driven to rotate in a direction indicated by an arrow by a drive motor (not shown), and is charged by a charging charger 9 provided above the photosensitive drum. Thus, the surface is uniformly charged.

Then, a laser beam modulated in accordance with image data by the optical writing unit 10 is irradiated while being irradiated in the main scanning direction of the photosensitive drum 8 while being exposed, and an electrostatic latent image is formed on the surface thereof. I do. A toner is attached to the electrostatic latent image by a developing unit 11 and developed to be a visible image.

On the other hand, each of the paper feed rollers 15 from one of the upper and lower two paper feed trays 6 and 7 provided in the printer body 1 or the paper feed unit 3 provided in the table 5 is provided.
A sheet (not shown) is selectively fed by one of the rotations a, 15b, and 15c, and the sheet stands by while being abutted against a pair of registration rollers 16 located near the photosensitive drum 8.

Then, in synchronization with the rotation of the photosensitive drum 8 carrying the toner image, the registration roller pair 16
Also starts rotating at a predetermined timing, and sends the sheet to a position facing the photosensitive drum 8 and the transfer / separation unit 17 provided below the photosensitive drum 8. As a result, the toner image on the photosensitive drum 8 is transferred to the sheet by the action of the transfer charger of the transfer / separation unit 17, and the sheet is separated from the photosensitive drum 8, and the fixing device is conveyed by the transport belt 18. 19, the transferred image is heated and fixed.

Thereafter, the path of the printed sheet is determined by the rotation direction of the switching roller 21 of the transport path switching device 20, which will be described in detail later, and the openable / closable discharge stacker 22 at the rear of the printer main body 1 is opened. , Upper discharge unit 4
Alternatively, it is selectively discharged to one of the lower duplex units 2. Reference numerals 23 and 24 denote transport roller pairs on the printer body 1 side and the paper discharge unit 4 side, and 25a and 25b denote paper discharge rollers for discharging sheets from the paper discharge unit 4 to the lower tray 4a and the upper tray 4b, respectively. RS is a sensor for detecting the presence or absence of a sheet disposed immediately before the pair of registration rollers 16.

After the toner image is transferred onto the sheet, the toner remaining on the photosensitive drum 8 is removed by the cleaning unit 14. Further, the residual potential of the photosensitive drum 8 is discharged by a discharge lamp 26. In this way, the photosensitive drum 8 is initialized and proceeds to the charging of the image forming process for the next page, and the same operation is repeated.

The printer body 1 further includes a controller 27 for controlling the entire laser printer and processing of print data and an engine driver 28 for controlling the printer engine constituting the image forming unit. And a power supply unit 29 and the like.

As shown in FIG. 1, the transport path switching device 20 includes a pair of feeding rollers 31 for feeding the sheet P, and an extension line L in the feeding direction of the sheet P passing through the nip Np of the pair of feeding rollers 31. And a switching roller 21 capable of rotating in the forward and reverse directions, and changing the rotation direction of the switching roller 21 to change the transport direction of the sheet P fed by the feed roller pair 31 to the discharge direction. The transport path 33 toward the unit 4 and the transport path 34 toward the duplex unit 2 are switched.

The switching roller 21 is rotationally driven in both forward and reverse directions by a motor (not shown) different from a motor for driving each part of the image forming system. In FIG. 1, reference numeral 35 denotes a pair of transport rollers for transporting the sheet P while pinching the sheet P provided on the transport path 34 corresponding to the pair of transport rollers 23.
Reference numerals 36, 37, and 38 denote guide plates for guiding the sheet P on the transport path, and reference numeral 12 denotes a fixing entrance sensor.

Next, a case will be described in which the sheet P continuously fed by the transport path switching device 20 is alternately switched to the transport path 33 and the transport path 34 in the traveling direction of each sheet and transported. This will be described with reference to FIGS. The arrows in the figure indicate the rotation direction of each roller.

FIG. 3A shows an extension of the leading end of the first sheet P1 in the sheet feeding direction through the nip of the pair of feeding rollers 31 (see the extension L in FIG. 1). ) Shows a state where it is in a position slightly pushed upward. At this time, the switching roller 21 has already rotated in the counterclockwise direction as indicated by the arrow to feed the first sheet P1 to the transport path 33 side.

When the leading end Pa of the first sheet P1 comes into contact with the switching roller 21, the leading end Pa of the sheet P1 rotates in the direction indicated by the arrow of the switching roller 21 as shown in FIG. It is guided to the transport path 33 side.

Thereafter, the first sheet P1 is guided by guide plates 36 and 37 as shown in FIG. 3C, and is nipped by the pair of transport rollers 23 to ascend in the transport path 33.
When the rear end Pb of the sheet P1 leaves the switching roller 21, the switching roller 21 changes its rotation direction clockwise as shown in FIG. 3D. Therefore, the feed roller pair 31 waits for the second sheet P2 fed at the next short interval in a state capable of receiving the second sheet P2.

Then, the sheet P2 is transferred to the switching roller 21.
And the leading end Pa of the sheet comes into contact with the roller, and as shown in FIG.
Is guided in the rotation direction indicated by the arrow. Accordingly, the sheet P2 is guided and guided by the guide plates 36 and 38, and is conveyed downward along the conveyance path 34 while being sandwiched between the conveyance roller pairs 35 as shown in FIG.

Next, when the trailing end Pb of the sheet P2 leaves the switching roller 21, the switching roller 21 rotates again in the counterclockwise direction, as shown in FIG. 4C. Therefore, the process waits in a state where the third sheet P3 fed by the feed roller pair 31 can be received next.

When the leading end Pa of the sheet P3 comes into contact with the switching roller 21, the leading end Pa of the sheet P is guided along the rotation direction of the switching roller 21 as shown in FIG. By repeating such a series of operations, even if the sheet is continuously fed to the transport path switching device 20, the sheet P can be alternately and efficiently switched to the transport paths 33 and 34 in the traveling direction and transported. it can.

By the way, in this transport path switching device 20,
When the sheet P guided by the switching roller 21 shown in FIG. 5 is conveyed while being nipped by the conveying roller pair 23 or 35, only a small area on the leading end side of the sheet P contacts the switching roller 21. I have. That is, this transport path
In the switching device 20 , a pair of transport rollers 23 and 35 are provided downstream of the switching roller 21 in each switching transport direction, respectively, and the sheet P guided by the switching roller 21 is nipped and transported by the pair of transport rollers 23 or 35. At this time, the sheet P is separated from the switching roller 21 as illustrated.

To achieve this, the transport path switching device
In 20 , the arrangement of the rollers is such that a straight line L ₁ connecting each nip between the feed roller pair 31 and the transport roller pair 23 and each nip between the feed roller pair 31 and the transport roller pair 35 are connected as shown in FIG. the straight line _{L 2,} the outer peripheral surface 21a of the switching roller 21
Have them arranged so that they do not wrap.

On the other hand, if the rollers are arranged as shown in FIG. 6 which does not satisfy the above conditions, the sheet P is conveyed while being nipped by the conveying roller pair 23 and the feeding roller pair 31. In this case, the intermediate portion Pc comes into contact with the outer peripheral surface 21a of the switching roller 21. Therefore, when the switching roller 21 is rotating in a direction different from the conveying direction of the sheet P as shown in FIG. The surface on the switching roller 21 side is rubbed by the switching roller 21. Therefore, if an image is formed on the surface, the image quality is degraded.

However, when the sheet P is nipped and conveyed by the conveying roller pair 23 or 35 in the conveying path switching device 20 as described above, the sheet P is separated from the switching roller 21, so that the intermediate position of the sheet P Part P
Since c is not rubbed by the switching roller 21, it is possible to prevent a decrease in image quality. Incidentally, the straight line L ₁ is exactly becomes the feeding roller pair 31 5 in the upper roller periphery and the conveying roller pair 23 right tangents switching roller 21 side that connects the outer periphery in straight rollers of the straight line L ₂ is a tangent line on the switching roller 21 side that linearly connects the outer periphery of the lower roller of the feed roller 31 and the outer periphery of the roller on the right side of the pair of conveying rollers 35.

FIGS. 7 and 8 show the state of conveyance of the sheet by the conveyance path switching device in which the rotation direction of the switching roller is changed before the trailing end of the sheet guided by the roller is separated from the switching roller. FIG.
The portions corresponding to are denoted by the same reference numerals.

In this transport path switching device , the switching rollers 21
Changes in the rotation direction of the sheet P guided by the rollers
Before the rear end Pb is separated from the switching roller 21. The operation contents, 7 and while referring to the sheet P fed continuously in the conveyance path switching device 8, the conveying path 3 and the transport path 33 in the traveling direction order of the sheet
The case where the sheet is conveyed while being alternately switched to No. 4 will be described as an example.

FIG. 7A shows that the leading end Pa of the first sheet P 1 is moved by the feed roller pair 31 to the third feed roller pair 31.
1 shows a state where the nip is pushed out of the nip. At this time, the switching roller 21 moves the first sheet P1
It has already been rotated in the counterclockwise direction indicated by the arrow to send it to 3. The leading edge Pa of the first sheet P1 is the switching roller 2
When the sheet P is in contact with the sheet P, as shown in FIG.
The leading end Pa is guided toward the transport path 33 by the rotation of the switching roller 21 in the direction indicated by the arrow.

Thereafter, the first sheet P 1 is guided to the transport path 33 by the guide plates 36 and 37 as shown in FIG. 7C, and the leading end Pa of the sheet P 1 is pinched by the transport roller pair 23. Then, when the switching roller 21 is transported upward in the transport path 33, the switching direction of the switching roller 21 is changed as illustrated to rotate clockwise.
Therefore, the rotation direction corresponds to the conveyance of the second sheet P2 to be fed next to the conveyance path 34.

When the sheet P2 is fed by the feed roller pair 31 and its tip Pa comes into contact with the switching roller 21, the tip Pa is rotated by the rotation of the switching roller 21, as shown in FIG. It is guided to the transport path 34 side. When the sheet P2 is nipped by the pair of conveying rollers 35 provided in the conveying path 34 and conveyed downward in the conveying path 34 in the figure, as shown in FIG.
The switching direction of the switching roller 21 is changed, and the switching roller 21 rotates counterclockwise. Therefore, the rotation direction corresponds to the conveyance of the third sheet P3 to be fed next to the conveyance path 33.

Next, the third sheet P3 is fed by the feed roller pair 31, and the leading end Pa of the third sheet P3 is
8, the switching roller 2 as shown in FIG.
The leading end Pa of the sheet P3 is guided in one rotation direction. By repeating a series of operations in this manner, while the preceding sheet is passing through the portion of the switching roller 21, the rotation direction of the switching roller 21 is changed for changing the traveling direction of the next sheet. Even if the sheet interval of the sheets P continuously fed to the conveyance path switching device is made extremely close to zero and the interval is very small, the conveyance path switching operation can be performed efficiently and reliably.

FIGS. 9 and 10 show an example of a conveyance path switching device using a switching belt capable of rotating forward and backward.
Ri, parts corresponding to those in FIG. 3 and FIG. 4 are designated by the same reference numerals. The conveying path switching device, shown in FIGS. 3 and 4
The only difference is that a switching belt 41 is used in place of the switching roller 21 with respect to the transport path switching device .

That is, a switching belt 41 is provided on the extension of the feeding direction of the sheet P passing through the nip of the feeding roller pair 31 and is capable of rotating forward and backward, and the rotating direction of the switching belt 41 is changed. Thus, the transport direction of the sheet P fed by the feed roller pair 31 is switched.

[0069] The case of transporting a operation by the conveying path switching device is switched alternately with the conveying path 33 a sheet fed continuously to the transportable <br/> sending passage switching device in the traveling direction order and conveying path 34 An example will be described. FIG. 9A shows a state in which the leading end of the _first sheet P1 is slightly pushed out by the feed roller pair 31 onto an extension of the sheet passing through the nip of the roller pair in the feed direction. . At this time, the switching belt 41 has already rotated counterclockwise as indicated by the arrow in order to feed the _first sheet P1 to the transport path 33 side.

When the leading end Pa of the first sheet P1 comes into contact with the switching belt 41, the leading end Pa of the sheet P1 is conveyed by rotation of the switching belt 41 in the direction indicated by the arrow, as shown in FIG. It is led to the road 33 side.

Thereafter, the first sheet P1 is guided by guide plates 36 and 37 as shown in FIG. 9C, and is nipped by the pair of conveying rollers 23 to ascend in the conveying path 33.
When the rear end Pb of the sheet P1 leaves the switching belt 41, the switching belt 41 changes its rotating direction clockwise as shown in FIG. 9D. Therefore, the switching belt 41 waits for the second sheet P2 fed at the next short interval in a state where it can accept the second sheet P2.

Then, the sheet P2 is transferred to the switching belt 41.
And the leading end Pa of the sheet comes into contact with the belt, as shown in FIG.
Is guided in the rotation direction indicated by the arrow. Therefore, the sheet P2 is guided and guided by the guide plates 36 and 38, and is conveyed downward in the conveying path 34 while being pinched by the conveying roller pair 35 as shown in FIG.

Next, when the rear end Pb of the sheet P2 leaves the switching belt 41, the switching belt 41 changes its rotating direction in the counterclockwise direction again as shown in FIG. Therefore, the process waits in a state where the third sheet P3 fed by the feed roller pair 31 can be received next.

When the leading end Pa of the sheet P3 comes into contact with the switching belt 41, the leading end of the sheet is guided along the rotating direction of the switching belt 41 as shown in FIG. By repeating such a series of operations,
Even if the sheet P is continuously fed to the transport path switching device, the sheet P can be alternately and efficiently switched to the transport paths 33 and 34 in the traveling direction and transported.

According to this transport path switching device , the use of the switching belt in the transport path switching device using the switching rollers of FIG. 1 enables a free layout suitable for various transport paths. This is also effective when, for example, it is desired to increase the distance from a pair of paper feed rollers for feeding a sheet to the transport path switching device to a pair of transport rollers for transporting the sheet while nipping the sheet in the switched transport path.

Incidentally, the conveyance path using this switching belt is cut off.
Also in conversion device, like the conveying path switching device using a switching roller described in FIG. 5 and 6, the straight line L connecting the respective nip of the feed roller pair 31 and the conveying roller pair 23 as shown in FIG. 11 ₃ and the straight line L ₄ connecting the respective nip of the feed roller pair 31 and the conveying roller pair 35, by setting the position as the belt surface 41a of the switching belt 41 does not wrap, switching belt middle portion of the sheet P 41 prevents the image from being rubbed, so that it is possible to prevent the image quality from deteriorating.

FIGS. 12 and 13 show a conveyance path switching device in which the rotation direction of the switching belt is changed before the trailing end of the sheet guided by the belt is separated from the switching belt.
Is a schematic diagram showing stepwise the conveyance state of the sheet location,
Parts corresponding to those in FIG. 9 are denoted by the same reference numerals. this
In the transport path switching device , the rotation direction of the switching belt 41 is changed before the rear end of the sheet P guided by the belt is separated from the switching belt 41.

The operation will be described by taking as an example a case in which a sheet P continuously fed to the conveyance path switching device is alternately switched to a conveyance path 33 and a conveyance path 34 in the traveling direction of the sheet, respectively. As shown in FIG. 12A, when the leading end Pa of the first sheet P1 comes out of the nip of the pair of feeding rollers 31 toward the switching belt 41, the switching belt 41 is already rotated in the opposite direction as indicated by the arrow. It is turning in the direction.

When the leading end Pa of the sheet P1 comes into contact with the switching belt 41, as shown in FIG. 12B, the leading end Pa of the sheet P1 is rotated by the switching belt 41 in the direction indicated by the arrow. It is guided to the transport path 33 side. afterwards,
The sheet P1 is placed on the guide plate 36 as shown in FIG.
When the leading end of the belt is conveyed to the ascending side in the conveying path 33 by being pinched by the conveying roller pair 23, the switching belt 41 changes its rotating direction and is shown in FIG. Rotate clockwise as shown.

Then, when the second sheet P2 is fed by the feed roller pair 31 and the leading end Pa comes into contact with the switching belt 41, as shown in FIG. Thereby, the front end Pa is guided to the transport path 34 side. When the sheet P2 is nipped by the pair of conveying rollers 35 provided in the conveying path 34 and conveyed downward in the conveying path 34 in the figure, as shown in FIG. The rotation direction of the belt 41 is changed again, and the belt 41 rotates counterclockwise.

Next, the third sheet P3 is fed by the feed roller pair 31, and the leading end Pa of the third sheet P3 is switched to the switching belt 41.
, The leading end of the sheet P3 is guided in the rotation direction of the switching belt 41 as shown in FIG. By such a series of operations, the preceding sheet is switched to the switching belt 4.
Since the rotation direction of the switching belt 41 for changing the traveling direction of the next sheet is changed while passing through the portion 1,
Even when the sheet interval of the sheets P continuously fed to the transport path switching device is extremely small, the transport path switching operation can be performed efficiently and reliably.

FIGS. 14 and 15 show a conveyance path switching provided by bringing the first and second driven rollers into contact with the switching rollers, respectively.
FIG. 4 is a schematic view showing a stepwise process of alternately transporting a sheet to two transport paths in the apparatus , and portions corresponding to FIG. 3 are denoted by the same reference numerals. In this transport path switching device , the first driven roller 43 and the second driven roller 44 that rotate in accordance with each transport direction of the sheet P whose transport direction has been switched by the switching roller 21 are connected to the switching roller 21. And the switching roller 21 is provided with a conveying force.

The operation of the transport path switching device is described as follows.
The case where the transfer is alternately switched to the transfer path 3 and the transfer path 34 will be described as an example. As shown in FIG. 14A, when the leading edge of the first sheet P1 comes out of the nip of the pair of feeding rollers 31 toward the switching roller 21, the switching roller 21 is already turned in the counterclockwise direction indicated by the arrow. It is turning. Also,
The switching roller 21 includes a first driven roller 43 and a second driven roller 43.
Of the switching roller 21 because the driven roller 44
, The driven rollers are respectively rotated in the directions indicated by the arrows.

Then, as shown in FIG. 14B, when the leading end of the sheet P1 comes into contact with the switching roller 21, the leading end of the sheet P1 is rotated in the direction indicated by the arrow.
1, the liquid is guided to the transport path 33 side, and is directly guided to a contact portion between the switching roller 21 and the first driven roller 43, that is, a nip. Since the nip between the switching roller 21 and the first driven roller 43 has a function of conveying the sheet to the conveying path 33, the sheet P1 is also subjected to the conveying force as shown in FIG. The sheet is conveyed (elevated) along the guide plates 36 and 37 in the conveyance path 33.

When the rear end Pb of the first sheet P1 moves away from the nip between the switching roller 21 and the first driven roller 43, the switching roller 21 is turned clockwise as shown in FIG. The rotation direction is changed, and the second sheet P2 to be fed next from the feed roller pair 31 is held. At the same time, the first and second driven rollers 43 and 44
Also rotate in the counterclockwise direction in reverse with the rotation of the switching roller 21.

When the leading end Pa of the second sheet P2 comes into contact with the switching roller 21 as shown in FIG. 15A, the leading end is guided in the rotating direction of the switching roller 21, so that the sheet P2 is 21 and the nip between the second driven roller 44. Since the nip between the switching roller 21 and the second driven roller 44 has a function of transporting the sheet to the transport path 34, the sheet P2 is transported by the nip as shown in FIG. It is conveyed along the guide plates 36 and 38 in the inside.

The rear end Pb of the sheet P2 is shown in FIG.
As shown in FIG. 5 (c), when the switching roller 21 moves away from the nip between the switching roller 21 and the second driven roller 44, the switching roller 21 changes its rotation direction counterclockwise. Wait for the third sheet P3 to come. At the same time, the first driven roller 43 and the second driven roller 44, both of which are in pressure contact with the switching roller 21, rotate counterclockwise in the clockwise direction.

When the third sheet P3 comes into contact with the switching roller 21 as shown in FIG. 15D, the leading end thereof is guided in the rotating direction of the switching roller 21, so that the sheet P3 is And the first driven roller 43, and is conveyed toward the conveyance path 33. By repeating such a series of operations, the traveling direction of the sheet continuously fed to the transport path switching device can be alternately switched to the transport paths 33 and 34, respectively.

According to this transport path switching device , the first driven roller 43 and the switching roller 21 which rotate in accordance with each transport direction of the sheet P whose transport direction has been switched by the switching roller 21, or the second driven roller 43, Can be conveyed while nipping the sheet P after the conveyance direction is switched by the driven roller 44 and the switching roller 21. The conveyance roller pairs are respectively brought close to the respective conveyance downstream sides of the switching roller 21. The number of parts can be reduced as much as there is no need to dispose, and the apparatus can be made compact.

FIGS. 16 and 17 show the switching of the transport path provided by bringing the first and second driven rollers into contact with the switching belt, respectively.
FIGS. 9 and 14 are schematic views showing a step-by-step process when a sheet is alternately conveyed to two conveying paths in the apparatus .
Are given the same reference numerals.

[0091] The conveyance path switching apparatus, conveyance path switching in Fig. 14
The only difference is that a switching belt 41 is used instead of the switching roller 21 for the switching device.
1 has a transfer force. The operation of the transport path switching device will be described by taking as an example a case where a sheet P continuously fed thereto is alternately switched to a transport path 33 and a transport path 34 in the traveling direction and transported.

As shown in FIG. 16A, when the leading end Pa of the first sheet P1 comes out of the nip of the pair of feeding rollers 31 toward the switching belt 41, the switching belt 41 is already in the position indicated by the arrow. It is rotating clockwise. Since the first driven roller 43 and the second driven roller 44 are both in pressure contact with the switching belt 41, the switching belt 41 rotates in the direction indicated by the arrow with respect to the rotation of the switching belt 41.

When the leading end Pa of the sheet P1 comes into contact with the switching belt 41 as shown in FIG. 16B, the leading end Pa of the sheet P1 is conveyed by the switching belt 41 rotating in the direction of the arrow. It is guided to the road 33 side, and is directly guided to the contact portion between the switching belt 41 and the first driven roller 43.

Since the contact portion between the switching belt 41 and the first driven roller 43 has a function of transporting the sheet to the transport path 33, as shown in FIG. Is conveyed (elevated) in the conveyance path 33 in a state where the conveyance force is applied to the conveyance force by the feed roller pair 31.

When the rear end Pb of the first sheet P1 is separated from the contact portion between the switching belt 41 and the first driven roller 43, the switching belt 41 rotates clockwise as shown in FIG. The rotation direction is changed in the direction, and the second sheet P2 to be fed next from the feed roller pair 31 is held. At the same time, the first and second driven rollers 43 and 44
Are rotated together with the rotation of the switching belt 41, so that they also rotate counterclockwise.

When the leading end Pa of the second sheet P2 comes into contact with the switching belt 41 as shown in FIG. 17A, the leading end Pa is guided in the rotating direction of the switching belt 41.
The sheet P2 is guided to the contact portion between the switching belt 41 and the second driven roller 44. The contact portion between the switching belt 41 and the second driven roller 44 has a function of transporting the sheet to the transport path 34.
17 is transported along the guide plates 36 and 38 in the transport path 34 as shown in FIG.

The rear end Pb of the sheet P2 is shown in FIG.
As shown in FIG. 7 (c), when the switching belt 41 moves away from the nip between the switching belt 41 and the second driven roller 44, the switching belt 41 changes its rotating direction counterclockwise, and the next feeding is performed by the feeding roller pair 31. Wait for the third sheet P3 to be sent. At the same time, the first driven roller 43 and the second driven roller 44 that are both in pressure contact with the switching belt 41 rotate counterclockwise, respectively, due to the co-rotation.

When the third sheet P3 comes into contact with the switching belt 41 as shown in FIG. 17D, the leading end Pa is guided in the rotating direction of the switching belt 41.
The sheet P3 is guided to a contact portion between the switching belt 41 and the first driven roller 43, and is conveyed toward the conveyance path 33. By repeating such a series of operations, the traveling direction of the sheet continuously fed to the transport path switching device can be alternately switched to the transport paths 33 and 34, respectively.

Incidentally, FIGS. 1 to 8 and FIGS.
In each transport path switching device of No. 5, the peripheral speed of the switching roller 21 may be set to be equal to or higher than the transport speed of the feed roller pair 31. For example, when the peripheral speed (conveying speed) of the feed roller pair 31 is V ₁ and the peripheral speed of the switching roller 21 is V ₂ , V
_{2 <assuming} that a V _1, when it abuts is guided in the rotational direction of the rollers leading end Pa of the sheet P to the switching roller 21 as shown in FIG. 18, the conveying speed V by the feeding roller pair 31 _This is because the sheet P tends to buckle before the switching roller 21 as shown in FIG. And <br/> rollers, if V ₂ ≧ V _1, a sheet P as shown in FIG. 19 can be prevented buckling from contact with the switching roller 21.

FIGS. 9 to 13 and FIGS. 16 and 17
Also in the conveyance path switching retrofit location shown in, switching belt 41
Is the peripheral speed of V ₃ , and the transport speed by the feed roller pair 31 is V
If ₁ and the and _{V 3} ≧ _{V 1} when, FIGS. 18 and 19
As in the case described above, buckling after the sheet P abuts on the switching belt 41 can be prevented.

FIG. 20 is a schematic view showing an example of a switching roller in which a large number of grooves orthogonal to the rotation direction are formed on the outer peripheral surface of the roller over the entire circumference to form a flat knurl, and FIG. FIG. 10 is a schematic view showing an example of a switching belt in which a plurality of grooves orthogonal to the movement direction are formed in parallel to form a flat knurl, and portions corresponding to FIGS. 1 and 9 are denoted by the same reference numerals.

In the conveying path switching device shown in FIG. 20, a large number of grooves 21b are formed on the outer peripheral surface 21a of the switching roller 21 in the direction (longitudinal direction) perpendicular to the rotation direction of the roller over the entire circumference to form a flat knurled shape. In the transport path switching device of FIG. 21, a large number of grooves 41b are formed on the belt surface of the switching belt 41 over the entire circumference and are formed in a flat knurled shape. If you do this,
The switchability of the sheet to each transport path is further improved.

Here, a problem that occurs when the switching roller 21 is made smooth without forming a flat knurl on the outer peripheral surface thereof with reference to FIGS. 22 and 23 will be described with reference to FIGS.
5 will be described when the flat knurls are formed on the outer peripheral surface of the roller by using the knurls.

As shown in FIG. 22, for example, if the front end Pa of the sheet P sent from the feed roller pair 31 is in a bent state as shown in FIG.
When the leading end Pa of the sheet P comes into contact with the sheet No. 1, the switching roller 21 cannot hold the leading end Pa as shown in FIG. 23, and thus guides the leading end Pa of the sheet in the rotation direction (upward in this case). You may not be able to do it. Therefore, the sheets P conveyed one after another at a predetermined sheet interval are jammed immediately before the switching roller 21.

However, as shown in FIG. 20, the outer peripheral surface of the switching roller 21 is formed into a flat knurl shape,
If the belt surface of the switching belt 41 is formed into a flat knurl shape as shown in FIG. 1, the sheet P sent from the feed roller pair 31 as shown in FIG.
Even when the sheet P is bent, when the leading end Pa of the sheet P abuts on the switching roller 21 as shown in FIG. 25, the switching roller 21 can reliably hold the leading end and guide it in the rotation direction of the switching roller 21. it can.

Therefore, the sheet P is not jammed immediately before the switching roller 21. Similarly, in the case of the switching belt 41, the sheet P does not become jammed immediately before the switching belt 41.

FIGS. 26 and 27 show an embodiment of the present invention .
FIG. 2 is a configuration diagram showing different operation states of a certain transport path switching device .
FIG. 8 is a schematic view showing a state in which sheets are alternately switched and fed to two conveyance paths in the embodiment in a stepwise manner. Parts corresponding to those in FIG. 14 are denoted by the same reference numerals.

In this embodiment, driven roller separating means 50A and 50B for separating the first and second driven rollers 43 and 44 from the switching roller 21 described with reference to FIG. The first or second driven roller 43 or 44 on the transport path side selected by
After the leading edge Pa of the sheet has passed through the driven roller, the sheet is separated from the switching roller 21 by driven roller separating means 50A and 50B.

The driven roller separation means 50A and 50B are the same, and the driven roller separation means 50A on the first driven roller 43 side includes a lever 51 rotatably supporting the first driven roller 43 at one end, A spring 52 for pulling the other end of the lever 51 upward in FIG. 26;
A support pin 53 for swingably supporting a substantially center of the lever 51
And a solenoid 54A that swings the lever 51 against the urging force of the spring 52.

When the solenoid 54A is in the off state, the lever 51 swings by the urging force of the spring 52, and the first driven roller 43 supported at one end of the lever 51 contacts the switching roller 21 with a predetermined pressing force. It comes into contact with it and rotates with the switching roller 21. Also, the solenoid 54
When A is turned on, as shown in FIG.
Swings against the biasing force of the spring 52, the first
Of the driven roller 43 is separated from the switching roller 21.

Similarly, the driven roller separating means 50B on the side of the second driven roller 44 includes a lever 51 having one end rotatably supporting the second driven roller 44, a spring 52,
The second driven roller 44 contacts the switching roller 21 when the solenoid 54B is off, and the second driven roller 44 is turned on when the solenoid 54B is turned on. It is separated from the switching roller 21.

The operation relating to the change of the sheet conveyance direction according to this embodiment is an example in which a sheet continuously fed to the conveyance path switching device is alternately conveyed to the conveyance path 33 and the conveyance path 34 in the traveling direction and conveyed. To explain. FIG.
When the leading edge of the first sheet P1 comes into contact with the switching roller 21 as shown in (a), the leading edge of the sheet P1 is guided in the rotation direction of the switching roller 21, and the switching roller 2
The first driven roller 43 is guided to a contact portion between the first driven roller 43 and the nip.

When the leading end of the sheet P1 passes through the nip between the switching roller 21 and the first driven roller 43, as shown in FIG.
As shown in (b), the first driven roller 43 is separated from the switching roller 21 when the solenoid 54A (FIG. 27) of the driven roller separating means 50A is turned on.

At the same time, the switching roller 21 reversely rotates in the clockwise direction, and rotates corresponding to the conveyance of the second sheet P2 to be fed next to the conveyance path 34.
Even if the first driven roller 43 is separated from the switching roller 21, the first sheet P 1 is conveyed on the conveying path 33 along the guide plates 36 and 37 by the conveying force of the feeding roller 31. .

When the second sheet P2 comes into contact with the switching roller 21 as shown in FIG. 28C, the leading end of the sheet P2 is guided in the rotation direction of the switching roller 21, and the switching roller 21 It is guided to a nip between the first driven roller 21 and the second driven roller 44.

When the leading edge of the sheet P2 passes through the nip between the switching roller 21 and the second driven roller 44, FIG.
(D), the second driven roller 44 is separated from the switching roller 21 when the solenoid 54B (FIG. 27) of the driven roller separating means 50B is turned on.

At the same time, the switching roller 21 reversely rotates in the counterclockwise direction, and has a rotation direction corresponding to the transport of the subsequently fed third sheet P3 to the transport path 33. Note that the second driven roller 44 is connected to the switching roller 21.
The second sheet P2 is separated from the feeding roller 31
Is transported along the guide plates 36 and 38 on the transport path 34 by the transport force of.

By repeating such a series of operations, the traveling direction of the sheet P continuously fed to the transport path switching device can be alternately switched to the transport paths 33 and 34, respectively.

According to this embodiment, the first and second driven rollers 43, 4 on the conveyance path selected according to the conveyance path switching.
4 is separated from the switching roller 21 after the leading edge of the sheet has passed, so that even if the rotation direction of the switching roller 21 is reversed while the sheet is passing through the position of the switching roller 21, the switching roller Since the sheet 21 has no conveying force, it does not hinder sheet conveyance.

Therefore, it is possible to quickly respond to switching of the transport direction of the next sheet to be fed. Therefore, when the sheets are continuously fed, even if the sheet interval is infinitely close to zero, the conveyance direction can be reliably switched.

Although not shown, in the conveying path switching apparatus using the switching belt described in FIG. 9 or the like instead of the switching roller, the first and second driven rollers are similarly used as the switching belt. Driven roller separating means for separating the first or second driven roller on the side of the conveyance path selected by the rotation direction of the switching belt, by the driven roller separating means after the leading end of the sheet passes through the driven roller. The same effect can be obtained even when the belt is separated from the switching belt.

FIGS. 29 and 30 show an embodiment of a transport path switching apparatus provided with a switching section retracting means for retracting the switching roller and a third transport path for linearly transporting the sheet. 2 are denoted by the same reference numerals.

In this transport path switching device, as shown in FIG. 29, there is provided a switching unit retracting means 60 for retracting the switching roller 21 from a position at which the transport direction of the sheet P shown can be switched to a retracted position shown in FIG. In addition, a transport path 61 serving as a third transport path in which the sheet P fed by the feed roller pair 31 is linearly transported when the switching roller 21 is retracted by the switching unit retracting means 60 is provided. .

In this embodiment, the switching unit retracting means 60 is means for retracting the switching roller 21 to the lower side with respect to the third transport path 61. In the retracted position, the switching roller 21 is moved to the feeding roller. The sheet P fed by the pair 31 is rotated in the arrow direction shown in FIG.

The switching unit retracting means 60 supports the switching roller 21 at one end of a lever 63 having a substantially central portion pivotally supported by a pin 62 so as to be rotatable in both forward and reverse directions. The movable shaft of the solenoid 64 is connected to the other end side. When the solenoid 64 is turned off, the lever 63 swings in the direction of arrow A in FIG. The position is regulated by a stopper (not shown) at a position where the sheet conveyance direction can be switched.

When the solenoid 64 is turned on, the lever 63 swings in the direction opposite to the direction indicated by the arrow A against the urging force of the spring 65. When the lever 63 moves to the retracted position shown in FIG. The position is regulated by. The switching unit retracting means 60 activates or deactivates the solenoid 64 in conjunction with opening and closing of a paper discharge tray 66 on which sheets discharged via the third transport path 61 are placed. The roller 21 is moved to a retracted position shown in FIG. 30 and to a position where the sheet conveyance direction can be switched as shown in FIG.

The operation or non-operation of the solenoid 64 is controlled by a control unit (not shown) for inputting an on / off signal from a switch 67 mounted on the left side surface of the printer main body 1 in FIG. That switch 67
Is turned on or off by opening and closing a sheet discharge tray 66 that is openably and closably attached to an exit portion of the third transport path 61 of the printer body 1.

That is, as shown in FIG. 29, when the discharge tray 66 is closed, the switch 67 is in the off state. In this state, the solenoid 64 is in the inoperative state. Is in the position shown in the drawing. When the discharge tray 66 is closed, the switch 67 is turned on as shown in FIG. 30, so that the solenoid 64 is activated and the switching roller 21 is moved to the retreat position. The sheet P is brought into contact with the lower surface of the sheet P fed linearly by the feed roller pair 31 to assist the conveyance thereof.

As described above, in this embodiment, since the position of the switching roller 21 is changed in conjunction with the opening and closing of the discharge tray 66, the opening and closing operation of the discharge tray 66 and the third transport path 61 are performed.
If the operation of switching the position of the switching roller 21 to the position where the sheet is conveyed is performed separately, the third conveyance path 61 may be moved to the discharge tray 6 depending on the operation mistake.
Although there is a possibility that the sheet may be conveyed to the closed state by 6, the sheet can be reliably conveyed and discharged without such a concern.

In addition to simply switching the sheet conveying direction between the two directions, the sheet can be conveyed linearly to the third conveying path 61, which is convenient. In addition, since the position of the switching roller 21 in the retracted state is retracted downward with respect to the third conveyance path 61 (FIG. 30), when the sheet is discharged through the third conveyance path 61, Switching roller 2
Since the sheet 1 contacts the lower surface of the sheet P fed by the feed roller pair 31 and assists the sheet P, the sheet P can be smoothly conveyed.

FIGS. 31 and 32 are schematic views showing only a main part of the embodiment in which a switching belt is used in place of the switching roller of FIG. 29. Parts corresponding to FIG. The code is attached. As shown in FIG. 31, the switching belt 41 can be retracted from a position at which the conveyance direction of the sheet P shown by the imaginary line can be switched to a retreat position shown by the solid line by means similar to the switching unit retreating means 60 shown in FIG. The sheet P can be linearly conveyed to the third conveyance path 61 in addition to switching the sheet P in two directions of the conveyance paths 33 and 34.

In the retracted position, as shown in FIG. 32, the switching belt 41 is brought into contact with the lower surface of the sheet P fed by the feed roller pair 31 so as to rotate in the direction indicated by the arrow to assist the conveyance. In this case, the switching belt 41
The conveyance of the sheet P toward the conveyance path 61 is assisted, so that the conveyance can be performed smoothly.

FIG. 33 is a schematic diagram showing only the main part of the transport path switching device in which the switching roller is a brush-shaped roller. In this transport path switching device , a brush-shaped switching roller 71 as shown in FIG. 34 is provided in a transport path switching section between the transport paths 33 and 34 as shown in FIG.

When the brush-shaped switching roller 71 is used as described above, when the sheet P is guided to the conveyance path 33, the sheet P passes through the fixing device 19 (see FIG. 2) as shown in FIG. The leading end portion of the sheet P that has reached the transport path switching device is guided toward the transport path 33 by the switching roller 71 rotating in the counterclockwise direction.

At the timing shown in FIG. 36 where the rear end Pb of the first sheet P1 is still in contact with the switching roller 71, the switching roller 71 is rotated clockwise in the reverse direction.
At this time, since the sheet P1 has already been nipped by the conveying roller pair 23 and conveyed upward in the conveying path 33, the reverse rotation of the switching roller 71 does not hinder the conveyance of the sheet P1. When the leading end of the next second sheet P2 comes into contact with the switching roller 71, the leading end of the sheet P2 is guided toward the transport path 34 so that the leading end of the sheet P2 is scraped along the rotation direction.

Similarly, as shown in FIG. 37, the leading end of the _third sheet P3 is guided toward the transport path 33 by the switching roller 71 whose rotation direction has been changed counterclockwise again. According to this transport path switching device , the transport direction of the sheet is switched by the brush-shaped roller, so that smooth high-speed transport switching can be performed without damaging the paper (sheet).

If the switching roller is a switching roller 81 made of a low-hardness rubber foam or a sponge material as shown in FIG. 38, the friction on the surface of the roller increases, so that the switching roller can be further moved in the sheet conveying direction. Switching performance can be improved. Further, if the switching roller 91 shown in FIG. 39 is formed in the shape of an impeller, air can flow in the shape of the impeller, so that the sheet that has passed through the fixing device is cooled. Since the fixation to the sheet surface can be promoted, it is useful to prevent toner rubbing or the like at the time of conveyance by the conveyance roller pair or the like on the downstream side.

FIG. 40 shows an embodiment of a conveyance path switching device in which a sheet can be branched into different conveyance paths in three directions, and portions corresponding to those in FIG. 33 are denoted by the same reference numerals. In this embodiment, two (three or more) switching rollers 71A, 71B (for example, a brush-shaped roller is shown, but other types of rollers may be provided). The sheet P fed by the feed roller pair 31 is transported in three different conveying paths 33, 34 and a third path.
In the rotation direction of the switching rollers 71A and 71B.
Branching is possible by changing the combination .

Then, the sheet P is transported straight to the third transport path 6.
40, the switching rollers 71A and 71B are respectively rotated in the directions shown by arrows in FIG. 40. When the rollers are conveyed to the conveyance path 33, the switching rollers 71A and 71B are rotated in the directions shown by arrows in FIG. In order to convey the rollers to the conveyance path 34, the rollers are rotated in the directions indicated by arrows in FIG.

In FIGS. 40 to 42, the switching rollers 71A and 71B are connected to the switching belt 41 described with reference to FIG.
The same operation and effect can be obtained by replacing with. By the way, in each transport path switching device using the above-described switching roller, the switching roller 21 or 71, 81, 9 is used.
1 and the like may be rotated for a predetermined period necessary for guiding the leading end of the sheet P fed to the roller by the feed roller pair 31 in a required conveying direction. In this case, the driving of the switching roller is also performed in the above-described manner.
Similar to the transport path switching device , a unique motor different from the main motor is used.

FIG. 43 is a waveform diagram showing an example in which a stop state is provided on the way to change the rotation direction in the drive control of the switching roller. As shown in this waveform diagram, in this example , a switching motor that drives a switching roller based on a detection signal that a fixing entrance sensor 12 (see FIG. 1) provided at the entrance of the fixing device 19 detects the leading edge and the trailing edge of the sheet. Is switched, and at this time, the rotation of the motor is controlled so as to rotate for a predetermined time (predetermined period) T.

That is, when the fixing inlet sensor 12 detects the leading end of the first sheet P1 and outputs a detection signal (ON), the switching motor is rotated clockwise (CW) for a predetermined time (predetermined period) T. After rotating the switching roller only by rotating it, it is stopped.

Then, the rear end of the sheet P1 is detected by the fixing entrance sensor 12 (the detection signal is not output. OF
F) Then, the switching motor is turned counterclockwise (CC
In W), the switching roller is reversely rotated for a predetermined time T to reversely rotate the switching roller. Therefore, the rotation of the switching motor is stabilized until the leading ends of the two subsequently fed sheets P2 abut on the switching roller, so that even in the case of a very small sheet interval, the sheet conveying direction is ensured. Can be switched to

In the above case, after the switching motor rotates in the clockwise (CW) direction for a predetermined time T and stops, and then reversely rotates in the counterclockwise (CCW) direction, the first sheet The sheet P1 is conveyed while being pinched firmly by the pair of conveying rollers 23 (in the case of guiding the sheet to the conveying path 33, and in the case of guiding to the conveying path 34, the pair of conveying rollers 35) shown in FIG. Even if the switching motor rotates in the reverse direction, the rotation of the
1 is reliably transported in the selected transport path.

In this example , a stop time (Ts in FIG. 43) is provided after the switching motor is rotated for a predetermined time T until the next rotation of the switching motor again. The generated noise can be reduced and the power consumption can be reduced. It is to be noted that during this stop time, it is the timing when the vicinity of the center of the sheet passes through the switching roller 21 portion.

[0146] Figure 44 shows an example <br/> you provided a constant speed state on the way when changing the rotational direction when switching motor for driving the switching roller is a motor capable of switching at high speed and constant speed It is a waveform diagram. In this example , the switching roller is a feeding roller pair (the switching roller 21 and the feeding roller pair 31 in FIG. 1).
) Is rotated at a peripheral speed Vf (high speed) higher than the linear speed Vs (constant speed) of the sheet for a predetermined period necessary for guiding the leading end of the sheet P fed in the required conveying direction, In other periods, the sheet P is rotated at the same peripheral speed as the linear speed Vs.

That is, the switching roller is turned clockwise (C
W) to the counterclockwise direction (CCW) will be described as an example. When the fixing entrance sensor 12 detects the leading edge of the first sheet P1 and outputs a detection signal, the switching to drive the switching roller is performed. Rotate the motor clockwise at high speed (V
The switching roller is rotated at a high speed by rotating it in f), and after a lapse of a predetermined time T, it is set to a constant speed rotation (Vs).

When the fixing entrance sensor 12 detects the rear end of the sheet P1 (the detection signal is no longer output), the switching motor is rotated in the counterclockwise direction (CCW) at a high speed (VW).
In f), the switching roller is reversely rotated for a predetermined time T to reversely rotate the switching roller at high speed. In this way, it is possible to reliably switch the sheet conveyance direction without stopping the rotation of the switching roller.

By the way, image forming apparatuses such as printers have a single-sided image forming (simplex) mode and a double-sided image forming (duplex) mode, and it is necessary to control the transport path switching device in accordance with each mode. is there. That is, in the simplex mode, it is only necessary to rotate the switching roller in one direction. However, in the case of a type in which a sheet is reversed using a duplex machine, the sheet is placed on a transport path to a paper feed port of the printer body. It is necessary to switch the transport path switching device in consideration of the number of sheets to be continuously fed to the duplex machine at the start of feeding, depending on whether or not the sheets are inserted.

[0150] Then, an inverted sheet (for double-sided printing) on which an image is formed on one side and a sheet newly fed (for single-sided printing, front-side printing) from a paper feed tray are alternately formed in the image forming unit. In the case of feeding, since the conveyance path switching device also alternately switches the conveyance path for feeding the sheet, if the control of the printing of the front side and the back side of the sheet is also used as it is for the control of the conveyance path switching apparatus, It is possible to efficiently control the transport path switching device during double-sided printing.

FIG. 45 is a schematic view showing an embodiment of a transport path switching device provided with a pair of switching rollers capable of switching the transport path of a sheet in three directions. FIG. 46 is a perspective view showing a main portion of the transport path switching device. FIG.

This transport path switching device forms first, second, and third transport paths, which branch the sheet P transported in the direction K indicated by the arrow in the transport path 80 shown in FIG. The transport direction is selectively switched to the transport paths 131, 132, and 133. The switching roller pair 84 disposed near the branch point of the transport path 80 and the rollers 85 and 86 of the switching roller pair 84 The first rotation drive means 90 shown in FIG. 46 for rotating the sheet P conveyed in the conveyance path 80 while nipping and conveying the sheet P in the direction of the arrow shown in FIG. A second rotation drive unit 100 is provided for rotating in both forward and reverse directions about a second drive shaft 101 which is a rotation axis parallel to the roller axis L of 84.

Then, the sheet P is pinched and conveyed by the pair of switching rollers 84, and the sheet P is rotated forward by the forward rotation of the switching roller pair 84 in the first direction indicated by arrow B in FIG. The reverse rotation of the switching roller pair 84 in the second direction indicated by the arrow C for guiding the sheet P on the outer circumference 84a and the reverse rotation of the switching roller pair 84 in the direction opposite to the direction of the arrow E indicate the forward rotation outer circumference 84b (the forward rotation outer circumference 84a).
The same as in the first embodiment, the conveyance direction of the sheet P conveyed along the conveyance path 80 can be switched to a third direction indicated by an arrow D for guiding the sheet P.

A pair of transport rollers 87 is provided at a branch point of the transport path 80, a pair of transport rollers 88 is provided at a portion of the second transport path 132 located downstream of the pair of switching rollers 84, and a third transport path 133 is provided. The transport roller pair 89 is disposed at a portion located on the downstream side of the switching roller pair 84.

The switching roller pair 84 is composed of rollers 85 and 86 vertically pressed against each other with a predetermined pressing force.
As shown in FIG. 6, one end of each of roller shafts 104 and 92 for integrally supporting the rollers 85 and 86 is rotatably held by a support plate 93 via a bearing (not shown), and the other end is similarly shown by a support plate 94. It is rotatably held via a bearing that does not.

A gear 95 is fixed to one end of one of the roller shafts 104, and a drive gear 97 fixed to one end of a first drive shaft 96 is disposed on the gear 95 so as to be meshable therewith. The shaft 96 is slidably held by a holding member (not shown) in the direction indicated by the arrow F as shown in FIG. 47 so that the drive gear 97 meshes with the gear 95 shown in FIG. 46 and the position where the meshing shown in FIG. It can be moved by a solenoid or the like.

The first drive shaft 9 to which the drive gear 97 is fixed
6 is fixed to the rotation shaft of a drive motor 98 shown in FIG. 46. When the roller 6 is rotated, the roller 85 rotates in the direction of arrow G and the driven roller 86 presses against it.
Rotates in the direction of arrow J.

As described above, the rollers 85 and 86 of the switching roller pair 84 are formed by the gear 95 and the driving gear 97 meshing therewith.
The sheet P to be conveyed is conveyed in the first direction shown by arrow B while nipping the sheet P conveyed in the conveying path 80 shown in FIG. 45 by the first rotary driving means 90 including the first driving shaft 96 and the driving motor 98 and the like. Direction.

Further, as shown in FIG. 46, the second drive shaft 101 is provided at the center of the front support plate 93,
At the center of the rotary shaft 4, rotating shafts 102 are respectively fixed outwardly on the same axis so as to correspond to the second drive shaft 101, and the shafts are rotatably supported by fixed portions of the apparatus. The rotation shaft of a drive motor 103 that rotates in both forward and reverse directions is integrally fixed to the second drive shaft 101.

Then, the switching roller pair 8 is driven by the drive motor 103 via the second drive shaft 101 and the support plate 93.
By rotating the entirety 4 forward in the direction of arrow E in FIG.
Its farthest from each other in the forward periphery 84a (a pair of rollers
The sheet P is guided in the second direction indicated by the arrow C along the outermost peripheral portions of the respective sheets, and is reversed in the direction opposite to the arrow E, so that the reverse rotation outer periphery 84b (same as the normal rotation outer periphery 84a). ), The sheet P is guided in a third direction indicated by a dashed arrow D.

As described above, the switching roller pair 84 including the rollers 85 and 86 is driven by the drive motor 103 and the second drive shaft 1.
The sheet P conveyed on the conveyance path 80 is integrally formed in a direction in which the sheet P conveyed in the conveyance path 80 is guided in the second and third directions by the second rotation driving means 100 including the rotation shaft 102, the rotation shaft 102, and the front and rear support plates 93 and 94. Is rotated. The drive motor 103
In this embodiment, a stepping motor is used so that the switching roller pair 84 can be easily positioned at the home position shown in FIGS. 45 and 46.

The gear 95 and the driving gear 9 shown in FIG.
In order to detect the home position of the drive gear 97 that meshes with the drive gear 7, a home position sensor such as a transmission type photo sensor is provided so that the position of the drive gear 97 can be detected. And make sure they engage. The movement of the drive gear 97 to the home position may be mechanically forcibly stopped at the home position by providing a stopper for regulating the slide position of the drive gear 97.

As described above, since the transport path switching apparatus according to this embodiment is configured, the sheet P transported in the direction K indicated by the arrow in the transport path 80 shown in FIG.
48, the position of the entire switching roller pair 84 in the rotational direction is fixed at the position shown in FIG. 48, and the driving gear 97 is moved to the home position where it meshes with the gear 95 as shown in FIG. By rotating the rollers 85 and 86, the rollers 85 and 86 are respectively rotated in the directions indicated by arrows in FIG.

As a result, the sheet P is moved between the rollers 85 and 8
6 while being conveyed to the first conveying path 131. When the sheet P is conveyed to the second conveyance path 132, the drive gear 97 is moved to a position where it meshes with the gear 95 as shown in FIG. Both are in the free state, and this time the drive motor 10 of the second drive means 100 shown in FIG.
3 is rotated in the forward direction, and a pair of switching rollers 84 of rollers 85 and 86 are rotated.
The whole is integrally rotated forward in the direction of arrow E in FIG. 45, and the sheet P is flipped upward in the figure by the forward rotation outer periphery 84a and guided to the second transport path 132 in arrow C.

Further, when the sheet P is conveyed to the third conveying path 133, the driving motor 103 is rotated in the reverse direction while the meshing between the driving gear 97 and the gear 95 is released. The entirety of the pair of switching rollers 85 and 86 (both in the free state) is reversed in the direction opposite to the direction indicated by the arrow E in FIG. 45, and the sheet P is knocked downward in FIG. Guide to 133.

According to this embodiment, the sheet P is guided in the three directions of the first, second, and third conveying paths 131, 132, and 133 by the rollers of the switching roller pair 84, respectively. It can be stably transported without being damaged when branching to the road. The engagement of the gear 95 and the drive gear 97 and the release of the engagement may be configured so that the drive gear 97 moves to the position shown in FIGS. 46 and 47 in conjunction with the rotation and stop of the first drive shaft 96. .

FIG. 49 shows an example of a conveyance path switching device in which a sheet guide member is provided instead of the switching roller pair, and portions corresponding to FIG. 45 are denoted by the same reference numerals. The conveyance path switching device includes a sheet guide member 114 disposed near a branch point of the conveyance path 80 and an entirety of the sheet guide member 114 substantially parallel to the sheet conveyance surface as indicated by an arrow K.
The drive shaft 111 (rotation axis) shown in FIG. 50 and the corresponding rotation axis 10
Rotation driving means 110 for rotating in both forward and reverse directions around 2
Are provided.

Then, the sheet guide member 114 at the predetermined stop position shown in FIG. 49 guides the sheet P in the first direction indicated by arrow B and the entire sheet guide member 114 is rotated forward in the direction indicated by arrow E by the forward rotation. The second direction of arrow C for guiding the sheet by the normal rotation outer circumference 114a and the reverse rotation of the entire sheet guide member 114 in the direction opposite to the direction of arrow E indicate a reverse rotation outer circumference 114b (same as the normal rotation outer circumference 114a). The conveyance direction of the sheet P conveyed along the conveyance path 80 can be switched to the third direction indicated by the arrow D for guiding the sheet P.

In this transport path switching device , the forward rotation outer circumference 114a and the reverse rotation outer circumference 114b are connected to the sheet guide member 1
The top and bottom guide plates 115 and 116 constituting the top and bottom ends 115a, 115b, and 11 in the transport direction, respectively.
6a and the trailing end 116b are the trajectories at the time of rotation, and their leading and trailing ends 115a and 115b and 116a and 116b
Of the drive shaft 11 shown in FIG.
1 and the position of the rotating shaft 102 are changed to upper and lower guide plates 115 and 11
6 is arranged in the middle of the height direction.

The rotation driving means 110 for rotating the entire sheet guide member 114 in both forward and reverse directions is provided with a drive shaft 11.
1, the rotating shaft 102, the drive motor 103, and the guide holding plate 11 in which the longitudinal ends of the upper and lower guide plates 115 and 116 are fixed and the drive shaft 111 is fixed outside the center.
7 and a guide holding plate 118 to which the rotating shaft 102 is fixed outside the center.

In this conveyance path switching device , when guiding the sheet P conveyed in the direction K indicated by the arrow in the conveyance path 80 of FIG. 49 to the first conveyance path 131, the sheet guide member 114 is moved to a predetermined position shown in the figure. At the stop position, the sheet P is guided linearly. When the sheet P is transported to the second transport path 132, the sheet guide member 114 is rotated forward in the direction indicated by the arrow E in FIG. The sheet P is flipped up in the figure by the forward rotation outer periphery 114a, and is guided to the second conveyance path 132 indicated by arrow C.

Further, when the sheet P is transported to the third transport path 133, the drive motor 103 is similarly rotated this time, and the sheet guide member 114 is rotated in the direction opposite to the direction indicated by the arrow E. The sheet P is guided to the third conveyance path 133 by hitting the sheet P downward in the figure by the outer periphery 114b. When returning the transport direction to the position shown in FIG. 49 for guiding the sheet P to the first transport path 131, the rotation position of the sheet guide member 114 is detected by a home position sensor or the like, and the position is shown. Drive motor 103
May be controlled so as to be stopped.

Alternatively, a mechanical stopping mechanism may be provided so that the sheet guide member 114 is forcibly stopped at the illustrated position and then the driving motor 103 is stopped. As shown in FIG. 51, the sheet guide member is connected to one of the guide plates 116 (or the guide plate 115 side).
The same effect can be obtained by displacing the sheet P only slightly below (in the case of the guide plate 115) the conveying line La of the sheet P conveyed on the conveying path 80 as shown in the figure. The effect can be achieved.

FIG. 52 shows a conveyance path constituted by a pair of rollers in which sheet guide members are arranged facing each other with a space therebetween.
This shows a switching device, and the portions corresponding to FIGS. 49 and 50 are denoted by the same reference numerals. This conveyance path switching device is different from the conveyance path switching device described with reference to FIGS. 49 and 50 in that a sheet guide member 124 constituted by a pair of rollers 125 and 126 disposed opposite to each other with a space therebetween instead of the sheet guide member 114. Only the point provided is different.

The rollers 125 and 126 are both rotatably held on roller shafts 127 and 128, and both ends of the roller shafts 127 and 128 are supported on the support plates 121 and 12 at both ends.
2, the drive shaft 111 is fixed to the center of the support plate 121, and the rotation shaft 102 is fixed to the center of the support plate 122 so as to face outward. By rotating in both directions,
Sheet guide member 12 including rollers 125 and 126
The entire structure 4 rotates in the forward direction indicated by an arrow E in FIG. 52 or in the opposite reverse direction.

According to this transport path switching device , the forward rotation outer circumference 1
The sheet is guided in the second direction (the direction indicated by arrow C in FIG. 49) or in the third direction (the direction indicated by arrow D in FIG. 49) by the outer periphery 24a or the reverse outer periphery 124b (substantially the same as the forward outer periphery 124a). In order to prevent the sheet from being damaged at the time, the conveyance path is switched as shown in FIG.
It is possible to prevent the device more reliably.

FIG. 53 is a schematic diagram for explaining the operation of the conveyance path switching device in which the conveyance path of the sheet conveyed at a high speed can be switched in a stepwise manner. In this embodiment, the conveyance path switching for switching the conveyance direction of the next sheet P2 before the rear end Pb of the preceding sheet P1 conveyed toward the branch point by the conveyance roller pair 87 passes through the switching roller pair 84. Perform the operation.

The operation of switching the transport path is exemplified by a case where the preceding sheet P1 is transported to the first transport path 131 described with reference to FIG. 45 and then the next sheet P2 is transported to the second transport path 132. explain.

As shown in FIG. 53 (a), the sheet P1 is conveyed along the conveying path in the direction of arrow K by the conveying roller pair 87, and the switching roller pair 84 is in a state where it is regulated to the position shown in FIG. The sheet P1 is conveyed to the first conveying path 131 (see FIG. 45) while being pinched by the rollers 85 and 86, and the rear end portion Pb of the preceding sheet P1 is still in the switching roller pair 8.
Before passing therethrough at the position 4, FIG.
As shown in (1), the entire switching roller pair 84 is normally rotated in the direction of arrow E.

At this time, the driving gear 97 described with reference to FIG.
Is located at a position distant from the gear 95 and has already been disengaged from the gear 95, so that the rollers 85 and 86 of the switching roller pair 84 are both free. Therefore, the sheet P is located between the rollers 85 and 86 in this manner.
Even if the switching roller pair 84 is normally rotated in the direction of arrow E as shown in FIG. 53C while the rear end portion Pb is located, the rollers 85 and 86 rotate freely. The end Pb easily comes off from those rollers, and the sheet P1
Is transported to the first transport path 131 (FIG. 45) without any trouble, and is transported by the transport roller pair 99.

When the leading edge Pa of the next sheet P2 reaches the switching roller pair 84, as shown in FIG. 53D, the switching roller pair whose leading edge Pa rotates forward in the direction of arrow E. It is swung upward in the figure by the forward rotation outer circumference 84a of 84 (see FIG. 45) and guided toward the second conveyance path indicated by arrow C. Therefore, the sheet P2 is set as shown in FIG.
As shown in (2), the sheet is conveyed by a pair of conveying rollers 88 provided in the second conveying path 132 (FIG. 45).

As described above, in this embodiment, the transport path switching operation for switching the transport direction of the next sheet P2 is performed before the rear end portion Pb of the preceding sheet P1 passes through the switching roller pair 84. Even if a sheet is conveyed at extremely small sheet intervals by high-speed conveyance, each sheet can be reliably guided to a target conveyance path.

Therefore, in the conventional conveyance path switching device, the conveyance path is switched by switching the positions of the branch claws or the like at the timing when the positions of the sheets that are continuously conveyed are located at the branch point. In the case where the sheet interval is extremely small by the high-speed conveyance and the image formation is performed efficiently, the conveyance path cannot be switched. However, according to the present embodiment, this can be achieved.

FIG. 53 shows an embodiment of the conveyance path switching apparatus in which the switching roller pair 84 is provided near the branch point. However, such a conveyance path switching operation is performed before the preceding sheet passes through the branch position. Performing earlier at the timing of FIG.
Each conveyor provided with a sheet guide member shown in 1 and 52
The same can be applied to the path switching device . In this case, the rear end of the sheet is provided with each of the sheet guide members 114,
Before passing through the sheets 116 and 124, a transport path switching operation for switching the transport direction of the next sheet is performed.

[0185]

As described in the foregoing, according to the present invention, by allowing abutment of the leading end of the sheet which is fed by the feeding roller pair switching roller or switching belt, it the switching roller or switching belt Since the sheet can be guided to the target conveyance path according to the rotation direction, even if the interval of the sheets conveyed on the conveyance path is extremely small, the sheet can be reliably switched to the target conveyance paths and conveyed. .

[0186]

[0187]

[0188]

[0189]

[0190]

[0191] Also, the first and second driven rollers have provided a driven roller separating means for separating from the switching roller or switching belt conveying path selected by the rotation direction of the rotation direction or switching belt switching roller First or second
Of the driven roller, the leading edge of the sheet above switching of the driven roller
Since the sheet is separated from the switching roller or the switching belt by the driven roller separating means after passing through the nip in contact with the switching roller or the switching belt , the rotation or rotation direction of the sheet while passing the nip of the switching roller or the switching belt is changed. Even if the sheet is reversed in the direction of conveyance of the sheet to be fed next, the switching roller or the switching belt loses the conveyance force due to the separation of the driven roller from the driven roller. Therefore, even if the sheets are continuously fed at extremely small sheet intervals close to zero, the conveyance direction can be reliably switched.

Further, if a switching section retreating means for retreating the switching roller or the switching belt is provided and a third transport path is provided, the switching roller or the switching belt is retracted by the switching section retreating means, so that the feeding roller pair is retracted. Can be linearly conveyed to the third conveyance path, thereby further improving the function.

The switching unit retreating means is means for retreating the switching roller or the switching belt to the lower side with respect to the third conveyance path, and rotates in a direction in contact with the sheet at the retraction position to assist the conveyance. Or if you rotate it,
When the switching roller or the switching belt conveys the sheet to the third conveyance path, they can function more effectively.

The switching unit retracting means switches the switching roller or the switching belt between the retracted position and the sheet conveying direction in conjunction with the opening and closing of the sheet discharge tray on which the sheet discharged via the third conveying path is placed. When the discharge tray is opened, the switching roller or the switching belt moves to the retreat position in conjunction with the opening of the discharge tray, so that the transport path can be switched without error. .

[0195]

The sheet passing through the nip of the feed roller pair
A plurality of switching rollers or switching belts are provided on the extension line in the feeding direction of, and the combination of their rotation directions is changed.
If possible branches the sheet to three directions or more different transport path by, 1 than the number of switching roller or switching belt
The sheets can be selectively switched and conveyed to a large number of conveying paths.

[0197]

[0198]

Further, a switching roller pair is disposed near the branch point of the transport path, and first rotation driving means for rotating each roller in the direction of transporting while holding the sheet between the rollers of the switching roller pair; A second rotation driving means for integrally rotating the pair of switching rollers in both the forward and reverse directions about a rotation axis parallel to the roller axis of the pair of switching rollers; Since the sheet is nipped and conveyed by the pair, or the entire switching roller pair is integrally rotated in both forward and reverse directions, and the sheet is guided to the target conveying path by the forward or reverse rotation outer circumference, so that a short switching operation is performed. One device can guide a sheet to a conveying path in three directions reliably and reliably in a time, so that the speed of the device can be increased. Also, a load was applied to the sheet as in the case of the branch claw method.
And does not damage the sheet.

[0200]

[0201]

[0202]

In each of the transport path switching devices, if the transport path switching operation for switching the transport direction of the next sheet is performed before the trailing edge of the sheet passes through the pair of switching rollers , the preceding sheet can be switched. Can be switched without waiting for the sheet to pass through the pair of switching rollers, so that the direction of conveyance of the next sheet to be conveyed can be quickly changed, and the sheet interval is extremely small. Also, the sheet can be reliably sent to each of the target conveying paths.

[Brief description of the drawings]

FIG. 1 is a prerequisite technique of a transport path switching device according to the present invention.
FIG. 3 is a schematic diagram illustrating the vicinity of an image forming unit that forms an image on a sheet of an image forming apparatus for explaining a technique .

FIG. 2 is a configuration diagram showing a laser printer equipped with the conveyance path switching device.

FIG. 3 is a schematic diagram showing in a stepwise manner an operation of alternately transporting a sheet continuously fed to the transport path switching device of FIG. 1 to two transport paths.

FIG. 4 is a schematic diagram showing an operation stage after the operation of FIG. 3;

FIG. 5 is an explanatory diagram for explaining a positional relationship between a feed roller pair and a transport roller pair when only a small area on the leading end side of a sheet is in contact with a switching roller.

FIG. 6 is a schematic diagram illustrating a positional relationship between a feed roller pair and a transport roller pair where an intermediate portion of a sheet comes into contact with a switching roller.

FIG. 7 is a conveyance path switching in which the rotation direction of the switching roller is changed before the trailing edge of the sheet separates from the roller.
FIG. 3 is a schematic diagram illustrating a sheet conveying state of the apparatus in a stepwise manner.

FIG. 8 is a schematic view showing a stage after FIG. 7 in a sheet conveyance state.

FIG. 9 is a schematic diagram illustrating a state in which a sheet is conveyed by a conveyance path switching device using a switching belt in a stepwise manner.

FIG. 10 is a schematic view showing a stage after FIG. 9 in a sheet conveyance state.

FIG. 11 is a schematic diagram illustrating a positional relationship between a feed roller pair and a transport roller pair for preventing a middle portion of a sheet from being rubbed by a switching belt.

FIG. 12 is a conveyance path disconnection in which the rotation direction of the switching belt is changed before the trailing edge of the sheet separates from the belt.
FIG. 4 is a schematic diagram illustrating a sheet conveying state of the changing device in a stepwise manner.

FIG. 13 is a schematic view showing a stage after FIG. 12 in a sheet conveyance state.

FIG. 14 is a schematic diagram showing stepwise a sheet conveyance state of a conveyance path switching device provided by bringing first and second driven rollers into contact with a switching roller.

FIG. 15 is a schematic view showing a stage after FIG. 14 in the sheet conveyance state.

FIG. 16 is a schematic diagram showing stepwise a sheet conveyance state of a conveyance path switching device provided by bringing first and second driven rollers into contact with a switching belt.

FIG. 17 is a schematic diagram showing a stage after FIG. 16 in a sheet conveyance state.

FIG. 18 is a schematic diagram for explaining a problem that occurs when the peripheral speed of the switching roller is lower than the transport speed of the pair of feed rollers.

FIG. 19 is a schematic diagram for explaining how the problem is solved when the peripheral speed of the switching roller is set to be equal to or higher than the transport speed of the feed roller pair.

FIG. 20 is a schematic diagram showing an example in which the outer peripheral surface of the switching roller is formed in a flat knurl shape.

FIG. 21 is a schematic view showing an example in which the surface of the switching belt is formed into a flat knurl shape.

FIG. 22 is a schematic diagram illustrating a state in which the leading end of a sheet fed by a feed roller pair and facing a switching roller is bent.

FIG. 23 is a schematic diagram showing a state in which the bent sheet abuts on the switching roller and is buckled.

FIG. 24 is a schematic diagram showing a state in which a sheet having a bent leading end approaches a switching roller having a flat knurled outer peripheral surface.

FIG. 25 is a schematic view showing a state in which buckling does not occur after the sheet in the bent state comes into contact with a flat knurled switching roller.

FIG. 26 is a schematic configuration diagram showing one embodiment of a transport path switching device according to the present invention .

FIG. 27 is a schematic configuration diagram showing a state in which one driven roller of the transport path switching device is separated from the switching roller.

FIG. 28 is a schematic diagram showing a sheet conveying state in a stepwise manner in the embodiment of FIG. 26;

FIG. 29 is a configuration diagram illustrating an embodiment in which a switching unit retracting unit that retracts the switching roller and a third conveyance path are provided.

FIG. 30 is a configuration diagram showing a state in which the switching roller has moved to a retracted position in the embodiment.

FIG. 31 is a schematic diagram showing only a main part of an embodiment in which a switching belt is used in place of the switching roller in the embodiment of FIG. 29.

FIG. 32 is a schematic view showing a state in which the switching belt has moved to a retracted position.

FIG. 33 is a schematic diagram showing only a main part of the embodiment of the transport path switching device in which the switching roller is a brush-shaped roller.

FIG. 34 is a perspective view showing the brush-shaped switching roller.

FIG. 35 is a schematic diagram showing a state in which a brush-shaped switching roller 71 guides a sheet toward a conveyance path 33;

FIG. 36 is a schematic diagram showing a state in which the switching roller guides a second sheet to the side of the conveyance path similarly.

FIG. 37 is a schematic view showing a state in which the switching roller guides a third sheet to the conveyance path 33 side.

FIG. 38 is a perspective view showing a switching roller 81 formed of a low-hardness rubber foam or a sponge material.

FIG. 39 is a perspective view showing a switching roller 91 formed in an impeller shape.

FIG. 40 is a schematic view showing an embodiment of a conveyance path switching device capable of branching a sheet to different conveyance paths in three directions.

FIG. 41 shows a sheet transport path 33 by the same device.
FIG.

FIG. 42 shows a sheet transport path 34 by the same device.
FIG.

FIG. 43 is a waveform diagram showing an example in which a stop state is provided halfway when changing the rotation direction of the switching roller.

FIG. 44 is a waveform diagram showing an example in which the switching roller is driven by a motor capable of switching between a high speed and a constant speed so that a constant speed state is provided in the course of changing the rotation direction.

FIG. 45 is a schematic diagram showing an embodiment of a conveyance path switching device provided with a switching roller pair capable of switching a sheet conveyance path in three directions.

FIG. 46 is a perspective view showing a main part of the transport path switching device.

FIG. 47 shows a driving gear 9 in the conveyance path switching device of FIG.
7 is a perspective view showing a state in which the gear 7 is moved to a position where the gear 7 is disengaged from the gear 95. FIG.

FIG. 48 is a schematic diagram showing a state in which a sheet P is conveyed to a first conveyance path 131 by the conveyance path switching device in FIG. 45.

FIG. 49 is a schematic view showing an example of a conveyance path switching device in which a sheet guide member is provided instead of a switching roller pair.

50 is a perspective view showing a sheet guide member 114 of the conveyance path switching device of FIG. 49 and its vicinity.

FIG. 51 is a schematic view showing an example of a conveyance path switching device in which a sheet guide member is constituted by only one guide plate.

FIG. 52 is a perspective view illustrating a conveyance path switching device including a pair of rollers in which sheet guide members are arranged facing each other with a space therebetween.

FIG. 53 is a schematic diagram for explaining step-by-step operation of a conveyance path switching device which is capable of switching a conveyance path of a sheet conveyed at a high speed.

FIG. 54 is a schematic view showing various operation states of a conventional transfer path switching device using a branch claw method.

[Explanation of symbols]

20 transport path switching device 21, 71, 8
1,91 Switching roller 21a Outer peripheral surface 23,35,87,8
8,89 transport roller pair 31 feed roller pair 33,34,8
0 Conveying path 41 Switching belt 41a Belt surface 43 First driven roller 44 Second driven roller 50A, 50B Driven roller separating means 60 Switching part retreating means 61, 133
Third transport path 66 Discharge tray 67 Switch 84 Switching roller pair 84a, 114a, 124a Forward rotation outer circumference 84b, 114b, 124b Reverse rotation outer circumference 85, 86, 85, 86, 125, 126 Roller 90 First rotation driving means 92 , 104,12
7, 128 Roller shaft 100 Second rotation driving means 98, 103
Drive motor 101 Second drive axis (rotary axis) 102 Rotary axis 111 Drive axis (rotary axis) 114, 124
Sheet guide member 131 First transport path 132 Second transport path P Sheet

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Shibaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Takefumi Takefumi 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Company, Ltd. (72) Inventor Shigeru Yamazaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company Limited (56) References JP-A-57-121551 (JP, A) JP-A Sho 61-86358 (JP, A) JP-A-3-95063 (JP, A) JP-A-61-99137 (JP, A) JP-A-63-183157 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65H 29/60

Claims (7)

(57) [Claims] A feed roller pair for feeding a sheet;
Extending the sheet feeding direction through the nip of the feed roller pair
Switching roller on the line and capable of forward and reverse rotationOr switching bell
GAnd the switching rollerOr switching beltDirection of rotation
Fed by the feed roller pair by changing
Switch the transport direction ofAlong with The transport direction is switched by the switching roller or switching belt.
First rotating in accordance with each transport direction of the replaced sheet
And a second driven roller as the switching roller or the switching belt.
The switching roller or the switching belt
To have the same transfer power, And the first and second driven rollers are the switching rollers or
A driven roller separating means for separating from the switching belt is provided.
Depending on the rotation direction of the switching roller or the switching belt.
To the switching roller or the switching belt on the selected conveying path side.
The first or second driven roller in the contact state is
The switching row of the first or second driven roller
After passing through the nip contacting the
The switching roller or the switching belt by a moving roller separating means;
Separate from Transport path switching characterized by
apparatus. (2)A pair of feeding rollers for feeding a sheet,
Extending the sheet feeding direction through the nip of the feed roller pair
A switching roller or switching bell on the line that can rotate forward and backward
And the rotation direction of the switching roller or the switching belt.
Fed by the feed roller pair by changing
Switch the transport direction of the sheet  Switch the switching roller or switching belt in the sheet conveyance direction.
A switching unit evacuation means for evacuation from a replaceable position is provided.
The switching roller or the switching roller
When the switching belt is retracted, the feed roller pair
Third transport path along which the fed sheet is transported linearly
A conveyance path switching device, comprising: 3. The transport path switching device according to claim 2 , wherein said switching unit retracting means is means for retracting said switching roller or switching belt downward with respect to said third transport path, and said retracting position. Wherein the switching roller or the switching belt is brought into contact with the sheet fed by the feed roller pair and rotated in a direction to assist the feeding thereof. 4. A transport path switching device according to claim 2 , wherein said switching unit retreat means interlocks with opening and closing of a paper discharge tray on which sheets discharged via said third transport path are placed. A transport path switching device, which is means for moving a switching roller or a switching belt between a retracted position and a position at which a transport direction of a sheet can be switched. A feed roller pair for feeding a sheet;
Extending the sheet feeding direction through the nip of the feed roller pair
As each row a plurality of switching roller or switching belt line
The sheet is provided so that it can be conveyed between
These are provided so that they can be rotated forward and backward, and
A conveyance path switching device wherein a sheet fed by the feed roller pair can be branched to three or more different conveyance paths by changing a combination of belt rotation directions . 6. A conveyance path switching device for selectively switching a sheet conveyed on a conveyance path to a plurality of conveyance paths, wherein the apparatus is disposed near a branch point of the conveyance path and conveys the conveyance path.
A pair of switching rollers for transporting a sheet to be transported while being sandwiched by a pair of rollers; and a first mechanism for rotating each roller of the pair of switching rollers in a direction in which the sheet transported through the transport path is transported while being clamped. a rotation driving means, the switching roller pair whole and front parallel to integrally said changeover switching roller pair of the roller axis
The outermost peripheral parts of the pair of rollers farthest from each other
Rotation center that will be located on the same outer peripheral line when rotating
Second rotation driving means for rotating the sheet conveyed in the conveyance path in both forward and reverse directions about the rotation axis provided in the switching roller pair.
And the second direction in which the sheet is conveyed while being held between the rollers.
A second direction in which the sheet is guided by a forward rotation outer circumference formed by a rotation locus of the outermost peripheral portion of each roller by forward rotation of the entire switching roller pair by the rotation driving means , and the second rotation.
By the reverse rotation of the entire pair of switching rollers by the driving means,
The conveyance direction of the sheet conveyed on the conveyance path can be switched between a third direction for guiding the sheet on the reverse rotation outer circumference formed by the rotation locus of the outermost peripheral portion of each roller. Transport path switching device. 7. A transport path switching device according to claim 6, wherein a transport path switching operation for switching the transport direction of the next sheet is performed before the trailing end of the sheet passes through said pair of switching rollers . A transfer path switching device characterized by the above-mentioned.