JP3365727B2 - Paper width direction correction mechanism - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet width direction correction mechanism applied to an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, as a sheet width direction correction mechanism as described above, there is a mechanism disclosed in, for example, Japanese Patent Laid-Open No. 7-89645.

In this mechanism, side guides are installed along the sheet conveying path, and skew rollers are provided corresponding to the side guides. When the fed sheet is skew-conveyed by the skew rollers, the side portions of the sheet come into contact with the side guides to correct the position of the sheet in the width direction of the sheet conveyance path, that is, in the direction orthogonal to the conveyance direction. The position of is corrected.

In this mechanism, the skew roller is displaceable between a drive position in contact with the sheet and a retracted position away from the sheet, and is located upstream of the skew roller (upstream side in the sheet transport direction). It is configured such that the conveying roller pair disposed in the position close to the sheet can switch between a pressure state in which the sheet is nipped and a non-pressure state (conveyance state and non-conveyance state). Then, at the time of feeding the paper, the pair of conveying rollers is pressed, the sheet is fed by the pair of conveying rollers, and the sensor detects that the leading end of the sheet has reached the position corresponding to the skew roller. Then, the skew roller is set to the driving position and the pair of conveying rollers is brought into a non-pressurized state. Then, when it is detected that the paper position correction is completed,
The skew roller is reset to the retracted position, the conveying roller pair is switched to the pressed state, and thereafter, the sheet is conveyed to the downstream side by driving the conveying roller pair.

[0005]

In the above-described conventional paper width direction correction mechanism, the skew roller can be displaced between the driving position and the retracted position as described above, and the skew roller can be displaced when the sheet position correction is completed. Is reset to the retracted position, the skewing force of the skewing roller does not act unnecessarily on the sheet whose position has been corrected. Therefore, there is a feature that the sheet is not easily bent even though the sheet is obliquely conveyed and brought into contact with the side guide.

However, since the skew roller is moved to the retracted position immediately after the position correction, there is a possibility that the sheet once corrected may be displaced again in the width direction. Therefore, the position cannot be properly corrected.

Further, after the position correction, the sheet is conveyed only by the pair of conveying rollers arranged on the upstream side of the skew roller in the conveying direction, and therefore there is a problem that a conveyance failure is likely to occur. That is, after the position correction, the paper is in contact with the side guides, so that the transfer resistance is generated due to friction. However, when the paper is transferred by the transfer roller pair as described above, it is mainly the rear end portion of the paper ( Since the sheet is conveyed by nipping the trailing end portion) in the traveling direction, the conveyance on the leading end side of the sheet is likely to be delayed due to the friction and the gradient of the sheet conveyance path, and a conveyance failure is easily induced.
Therefore, it is necessary to improve so that the position-corrected sheet can be conveyed more smoothly.

The present invention has been made in order to solve the above-mentioned problems, and while properly correcting the position in the paper width direction, it is possible to smoothly convey the paper while suppressing the occurrence of bending. It is intended to provide a direction correction mechanism.

[0009]

In order to solve the above-mentioned problems, the present invention is directed to a reference member installed in the sheet conveying direction along a sheet conveying path and a sheet skewed with respect to the conveying direction. A conveyance state in which a sheet can be conveyed in a sheet width direction correction mechanism that includes a skew roller, and causes the sheet to contact the reference member by the skew roller to correct the position of the sheet in the width direction of the sheet conveyance path. And a non-conveying state, a conveying roller pair that can be switched to a non-conveying state is provided on the downstream side of the skew roller in the conveying direction, and a detecting unit that detects that the position of the sheet is corrected is provided. The pair of conveying rollers is held in a non-conveying state, the skew rollers are driven with respect to the sheet at least while each sheet passes through the skew rollers, and the conveying is performed based on detection of correction completion by the detecting unit. It is obtained to switch the conveyance state over roller pair (claim 1).

According to this mechanism, since the skew roller is driven until the sheet passes the skew roller, after the side in the traveling direction of the sheet contacts the reference member, that is, after the position correction is completed. Also, the skewing force is continuously applied to the paper. Therefore, the paper does not separate from the reference member. In addition, after the position correction, the pair of transport rollers arranged on the downstream side of the skew roller is switched to the transport state, and the sheet is pulled downstream in the transport direction (that is, the transport force is applied). Therefore, it is assumed that a force in the combined direction of the conveying force of the conveying roller pair and the skewing force of the skewing roller, that is, a force in a direction parallel to the conveying direction acts on the sheet. As a result, the skewing force acting on the sheet is alleviated, and the sheet becomes difficult to bend.

Further, after the position correction, the skew roller and the conveying roller pair on the downstream side are driven. Therefore, after the position correction, the skew roller is retracted and the sheet is fed only by the conveying roller pair on the upstream side. Compared with this type of device, the conveying force can be applied to the front side of the paper. Therefore, the sheet can be smoothly transported without being delayed on the leading edge side.

In the above mechanism, especially when the non-conveying state is switched to the conveying state, the conveying roller pair is arranged so that the leading end portion in the traveling direction of the sheet can be nipped (claim 2). ), The conveying force is surely applied to the leading end of the sheet, and the sheet can be conveyed more smoothly.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a sheet conveying path of a copying machine to which the sheet width direction correcting mechanism of the present invention is applied, for example, upstream of a pair of registration rollers for aligning the leading edge of the sheet, that is, upstream in the sheet conveying direction. Showing the side.

In the sheet conveying path 10 shown in this figure, a pair of conveying rollers 12 and 1 are arranged in this order from the upstream side in the sheet conveying direction.
4 is provided, and a guide member 16 (reference member) having a guide surface 16a parallel to the transport direction is disposed between the transport roller pairs 12 and 14. The guide member 16 is arranged in the width direction of the sheet conveying path 10, that is, in the vicinity of one side end portion (near the front end portion in FIG. 1) in the direction orthogonal to the conveying direction on the sheet conveying surface.

Further, at a position closer to the center than the guide member 16 in the width direction of the paper transport path 10, the skew roller 20 for skew-transporting the paper toward the guide member 16 is provided.
Is provided. The skew roller 20 has a mounting member 22.
The roller 20 is mounted on the frame of the copying machine through the mounting member 22 so that the roller 20 is in contact with the paper. The rotating shaft 21 of the skew roller 20 is connected to a drive shaft 24 supported by the frame via a universal joint 26, as shown in FIG. The drive shaft 24 is connected to a drive motor via a rotational force transmitting means such as a gear (not shown) so that the skew roller 20 is rotated by receiving the rotational drive force of the drive motor. Has become.

The pair of transport rollers 12 and 14 both nip and transport a sheet by a pair of upper and lower rollers.
Of these transport roller pairs 12 and 14, the downstream transport roller pair 14, in particular, is configured such that one roller can be brought into contact with and separated from the other roller, although not shown.
According to a solenoid drive (not shown), the two rollers are switched between a pressed state (conveying state) in which they are pressed against each other and a non-pressurizing state (non-conveying state) in which they are separated from each other.
Then, while the sheet is nipped and conveyed by both rollers in the pressurized state, in the non-pressurized state, the two rollers are separated so that the sheet can pass between the both rollers.

The position of the conveying roller pair 14 is set to a position where the leading end portion (leading end portion in the sheet advancing direction) of the sheet can be nipped when the sheet position correction is completed. Such a position is experimentally determined by, for example, repeatedly transporting a large number of sheets and knowing the tendency of the leading edge position of the sheet when the position correction is completed.

In the figure, reference numerals 30, 32, and 34 denote sensors for detecting a sheet, which are embedded in the conveying surface, and the sensors 30 and 32 are a pair of conveying rollers 12 at the center of the sheet conveying path 10 in the width direction. 14 is provided on the downstream side of the guide roller 1, and the sensor 34 is provided on the upstream side of the pair of conveying rollers 14 and
It is arranged along 6a. As a result, the position of the sheet in the transport direction is detected based on the sheet detection by the sensors 30 and 32, while it is detected that the position of the sheet is corrected in the width direction based on the sheet detection by the sensor 34. It is like this. That is, when the position of the paper in the width direction of the paper transport path 10 is corrected, the guide surface 16
Since the sheet comes into contact with a, it is possible to detect that the position of the sheet has been corrected by detecting the sheet with the sensor 34 arranged along the guide surface 16a. That is, the sensor 34 constitutes the detection means of the present application.

These sensors 30, 32, 34 are, for example, reflection type sensors, and are configured to detect the presence or absence of paper by reflecting the emitted light on the paper and receiving it. During the operation of the copying machine, the sensors 30, 32
The operation timing of the skew roller 20 is determined based on the detection of the sheet by the sensor, and the state switching timing of the transport roller pair 14 is determined based on the detection of the sheet by the sensor 34, that is, the transport roller pair 14 is not pressed. The timing for switching to the pressurized state is designed.

The sensor 32 arranged on the downstream side of the conveying roller pair 14 detects the leading edge of the sheet at the position where the trailing edge of the sheet has completely passed the skew roller 20 in relation to the sheet. It is installed in.

Next, the operation of correcting the position of the sheet on the sheet conveying path 10 configured as described above will be described with reference to the timing chart of FIG.

In the paper feed path 10, the paper P is
On the upstream side of the pair of conveying rollers 12, the sheet is fed in the direction shown by the white arrow in FIG. At this time, the conveying roller pair 14 is in a non-pressurized state, and the skew roller 20 is stopped. It should be noted that the pair of transport rollers 12 and 14 are always rotationally driven while the sheet P is being transported.

First, when the sheet P passes through the conveying roller pair 12 and the leading edge thereof is detected by the sensor 36 (t1
At the time point), the rotational driving force of the drive motor is transmitted to the skew roller 20 according to the operation of a solenoid (not shown).

Then, when the sheet P is further conveyed and the leading end thereof reaches the skew roller 20, the skew force by the skew roller 20 is applied while the sheet P is transported by the pair of transport rollers 12 and the skew roller 20. The paper P acts and the guide member 16
It is conveyed obliquely toward. As a result, the side edge of the paper P contacts the guide surface 16a and follows the guide surface 16a, and the widthwise position of the paper P in the paper transport path 10 is corrected as shown in FIG.

When the position correction of the paper P is completed,
That is, when the sheet P is detected by the sensor 34 (at time t2), the transport roller pair 14 is switched from the non-pressurized state to the pressurized state, and the leading end portion of the sheet P is nipped by the transport roller pair 14. As a result, the sheet P is sent to the downstream side by driving the pair of conveying rollers 14 and the skew roller 20. It should be noted that the leading edge of the paper P is the pair of transport rollers
When the position of the sheet P is not corrected in the state where the number of sheets reaches 4, the front end of the sheet passes between the rollers of the pair of transport rollers 14 and is further transported to the downstream side, and the skew roller 20 performs skew transport. Will be performed.

When the sheet P is conveyed in this manner and the leading edge of the sheet P is detected by the sensor 32 (at time t3), the skew roller 20 is stopped, the sheet P is further conveyed, and the sheet P passes through the sensor 32. Then (at time t4), the conveyance roller pair 14 is switched to the non-pressurized state in synchronization with this.

According to the above structure, the sheet P is completely skewed regardless of whether or not the position correction of the sheet P is completed.
The skew roller 20 is driven until the sheet passes through. Therefore, the skewing force of the skewing roller 20 always acts on the sheet P, and the side of the sheet P is completely in contact with the guide surface 16a, that is, the position after position correction is maintained. The sheet P is conveyed to the downstream side in the closed state.

For this reason, there is no risk that the sheet whose position has been once corrected will be displaced again like the conventional mechanism of this type in which the skew roller is immediately moved to the retracted position after the position of the sheet is corrected. The position correction in the width direction of the sheet conveyance path 10 is surely performed.

Moreover, after the position correction, the conveying roller pair 14 is switched to the pressure state as described above, and the conveying force is applied to the paper P by the conveying roller pair 14,
Even if the skew roller 20 is continuously driven as described above, the paper P is difficult to bend.

That is, a combined force of the conveying force of the conveying roller pair 14 and the skewing force of the skewing roller 20, that is, a force in a direction parallel to the conveying direction acts on the sheet P after the position correction. This means that the skewing force acting on the paper P is alleviated. Therefore, after the position correction, the skew roller 20 is driven as described above to correct the paper P.
Although the position P is surely maintained, the paper P hardly bends.

In addition, after the position correction, the conveying roller pair 14
Since the sheet P is transported by the skew feeding roller 20 and the skew feeding roller 20, as compared with the conventional apparatus of this type, after the position correction, the skew feeding roller is retracted and the sheet is transported only by the transport roller pair on the upstream side thereof. It is possible to apply a greater carrying force, and it is also possible to apply a carrying force to the portion of the paper P on the leading edge side. Therefore, after the position correction, the conveyance of the sheet P is not delayed on the leading edge side of the sheet, and the sheet P can be conveyed very smoothly.

Therefore, according to the configuration of the sheet conveying path 10 as described above, the position of the sheet P in the width direction can be surely corrected and the sheet P can be smoothly conveyed while suppressing the deflection.

The paper transport path described in the above embodiment is one embodiment of the paper transport path to which the paper width direction correction mechanism of the present invention is applied, and the specific configuration of the paper transport path and the paper transport path are described. The specific configuration of the width-direction correction mechanism can be appropriately changed without departing from the scope of the present invention.

For example, in the above-described embodiment, the conveying roller pair 14 is arranged so that the front end portion of the paper P in the traveling direction can be nipped when the position correction of the paper P is completed, but the front end of the paper P is not always necessary. It is not necessary to arrange the parts so as to nip, and the downstream side of the skew roller 20
At least while the skew roller 20 is being driven, the pair of transport rollers 14 is at a position where a transport force can be applied to the sheet P after the position correction.
Should be arranged. However, since conveyance resistance is generated on the sheet P after the position correction due to contact friction with the guide member 16 and conveyance is likely to be delayed at the leading end side of the sheet P, it is preferable that the sheet P be corrected immediately after the position correction as in the above embodiment. On paper P
It is preferable to arrange the conveying roller pair 14 so that the leading end of the sheet can be nipped. With this configuration, in addition to the friction with the guide member 16, the paper P can be smoothly transported even when the paper transport path 10 has an upward slope.

In the above embodiment, the single sensor 34 is used to detect the paper P. However, for example, the two sensors are arranged apart from each other along the guide surface 16a, and both sensors are used. The completion of the position correction of the paper P may be detected based on the detection of the paper P. By doing so, it is possible to reliably detect the state where the side edges of the sheet P are in contact with the guide surface 16a from the leading edge to the trailing edge by detecting any two points on the side edges of the sheet P. It is possible to detect the position correction completed more accurately.

In the above embodiment, an example in which the paper width direction correction mechanism of the present application is applied to a copying machine has been described. However, the mechanism of the present application is applied to an image forming apparatus such as a printer or a facsimile other than the copying machine. Of course, it is applicable.

[0038]

As described above, the present invention provides a sheet width direction correction mechanism in which the sheet is brought into contact with the reference member by the skew rollers to correct the position of the sheet being conveyed in the width direction. Since the skew roller is driven with respect to the sheet at least while each sheet passes through the skew roller, the position of the sheet after the correction can be reliably maintained. Moreover, before the position correction, the conveying roller pair on the downstream side of the skew roller is set in the non-conveying state, and this is switched to the conveying state when the position correction is completed. The bending force of the paper can be suppressed by effectively relaxing the running force, and the paper can be conveyed while applying the conveying force to the front end side of the paper. Therefore, it is possible to appropriately perform the position correction in the paper width direction, and at the same time, to smoothly convey the paper while suppressing the occurrence of bending.

Especially, when the non-conveying state is switched to the conveying state, the conveying roller pair is arranged so that the leading end portion in the traveling direction of the sheet can be nipped.
Since the conveying force can be applied to the leading edge of the paper,
The paper can be transported more smoothly.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a sheet conveyance path of a copying machine to which a sheet width direction correction mechanism according to the present invention is applied.

FIG. 2 is a timing chart illustrating a paper position correction operation.

FIG. 3 is a schematic diagram illustrating position correction of a sheet in the width direction.

[Explanation of symbols] 10 Paper transport path 12,14 Conveyor roller pair 16 Guide member 16a guide surface 20 skew rollers 30, 32, 34 sensors P paper

Claims (2)

(57) [Claims] 1. A reference member installed in a sheet conveyance direction along a sheet conveyance path, and a skew roller for skewing the sheet with respect to the conveyance direction. The skew roller causes the sheet to be a reference member. In the sheet width direction correction mechanism for correcting the position of the sheet in the width direction of the sheet conveyance path, the pair of conveyance rollers capable of switching between the conveyance state in which the sheet can be conveyed and the non-conveyance state are provided as skew rollers. In addition to being provided on the downstream side of the conveyance direction, a detection unit for detecting that the position of the paper has been corrected is provided, and at the time of paper conveyance, the conveyance roller pair is held in a non-conveyance state and at least each paper is While passing the skew roller, the skew roller is driven with respect to the sheet, and the transport roller pair is switched to a transport state based on detection of completion of correction by the detection unit. Paper width direction correction mechanism. 2. The sheet width direction according to claim 1, wherein when the sheet is switched from the non-conveying state to the conveying state, the conveying roller pair is arranged so as to nip the leading end portion in the traveling direction of the sheet. Correction mechanism.