JP2004051256A - Sheet misregistration correction device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately correct the misregistration of a sheet conveyance position even when the productivity of image formation is increased. <P>SOLUTION: This sheet misregistration correction device comprises a a pair of register rolls 1 conveying a sheet P and moving the sheet P in the direction vertical to the conveying direction, a side sensor 2 detecting the position of the sheet P conveyed by the pair of register rolls 1 along the vertical direction to the conveying direction, a moving means 20 moving the side shift sensor 2 along the direction vertical to the sheet P conveying direction according to the size of the sheet P, and a moving control means 21 moving the side shift sensor 2 to a position matching the size of the next sheet P by the moving means 20 before the sheet P passes the pair of register rolls 1 after a position correction in the direction vertical to the sheet P conveying direction is performed by the movement of the pair of register rolls 1 based on the detection of the sheet P by the side shift sensor 2. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
1. Field of the Invention The present invention relates to a sheet positional deviation correcting device that corrects a positional deviation in sheet conveyance and an image forming apparatus including the same.
[0002]
[Prior art]
Conventionally, in correcting the position (side registration position) in the direction perpendicular to the transport direction in the transport of the paper, the side edge of the paper is detected by a sensor (side shift sensor), and the transport of the registration roll pair or the like is performed according to the detection signal. Means is used in which the roll is moved in a direction perpendicular to the paper transport direction to make the side registration position of the paper coincide with the image writing position.
[0003]
Further, when the paper arrangement reference in image formation is the center of the paper, it is necessary to move the side shift sensor according to the paper size, and a motor and a motor for moving from a predetermined home position by a distance corresponding to the paper size. A driving mechanism such as a belt is provided (see JP-A-8-108956, JP-A-9-90686, JP-A-2-198952, JP-A-2-178147, etc.).
[0004]
[Problems to be solved by the invention]
Here, in recent image forming apparatuses, from the viewpoint of high productivity, there is an increasing demand to increase the sheet conveyance speed and to narrow the interval between sheets continuously fed. However, when sheets of different sizes are successively sent, the position of the side shift sensor must be moved between the sheets in accordance with the size of the next sheet, so that the sheet conveyance speed increases, When the interval between the sheets becomes narrow, there is no time allowance for the movement of the side shift sensor, which hinders an improvement in productivity.
[0005]
[Means for Solving the Problems]
The present invention has been made to solve such a problem. That is, the present invention detects a pair of registration rolls for conveying a sheet and moving the sheet in a direction perpendicular to the conveyance direction, and a position along a direction perpendicular to the conveyance direction of the sheet conveyed by the pair of registration rolls. A side shift sensor, moving means for moving the side shift sensor along a direction perpendicular to the sheet conveyance direction according to the size of the sheet, and a sheet by moving the registration roll pair based on the sheet detection by the side shift sensor. After the position is corrected in the direction perpendicular to the transport direction of the sheet, and before the sheet passes through the pair of registration rolls, the side shift sensor is moved by the moving unit to a position corresponding to the size of the next sheet. This is a sheet position deviation correction device. Further, the present invention is also an image forming apparatus provided with the sheet position deviation correcting device.
[0006]
In the present invention, the side shift sensor detects the position in the direction perpendicular to the sheet conveyance direction by the side shift sensor, corrects the position, and then moves the side shift sensor by the moving unit before the sheet passes through the registration roll pair. Because the paper is moved to a position that matches the size of the paper, even if the paper transport speed is increased or the paper gap is narrowed, the next paper misalignment can be immediately detected and corrected. .
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1A and 1B are schematic diagrams illustrating a paper position deviation correcting apparatus according to the present embodiment, wherein FIG. 1A is a configuration diagram of a main part, and FIG. 1B is a configuration diagram of a side shift sensor unit. That is, the paper position deviation correcting device is mainly applied to a mechanism for feeding a paper in an image forming apparatus such as a copying machine or a printer.
[0008]
The paper position shift correction device includes a pair of registration rolls 1 that transports the paper P and moves the paper P in a direction perpendicular to the transport direction, and a side shift sensor that detects a position along the direction perpendicular to the transport direction of the paper. 2, a moving means 20 for moving the side shift sensor 2 in a direction perpendicular to the transport direction of the paper P in accordance with the size of the paper P, and controlling the timing and amount of movement of the side shift sensor 2 by the moving means 20 And a movement control means 21 for performing the operation.
[0009]
The registration roll pair 1 is configured by forming a pair of rolls attached to a shaft. The rotation of the rotation driving unit 10 causes the pair of rolls to rotate in opposite directions, and nips the paper P inserted therebetween. It is transported in a state.
[0010]
A shift drive unit 11 is provided at one end of the shaft of the registration roll pair 1, and the shaft is moved by the drive of the shift drive unit 11 to move the registration roll pair 1 in a direction perpendicular to the sheet P conveyance direction ( (Axial direction). That is, by moving the registration roll pair 1 in the axial direction while transporting the paper P, it is possible to correct the positional deviation in the direction perpendicular to the transport direction of the paper P.
[0011]
The side shift sensor 2 is attached to a belt 22, and the belt 22 is hung on a pulley. The moving means 20 rotates one of the pulleys to move the belt 22. The direction of movement of the belt 22 is determined by the direction of rotation of the moving means 20, and the side shift sensor 2 can move in a direction perpendicular to the direction in which the sheet P is conveyed.
[0012]
Further, a side shift home sensor 3 is provided to detect a reference position (home position) of the side shift sensor 2. An arm is attached to the side shift sensor 2, and the position at which the tip of the arm is detected by the side shift home sensor 3 is defined as the home position of the side shift sensor 2.
[0013]
The movement of the side shift sensor 2 is controlled by the movement control means 21. That is, the rotation direction and the amount of rotation of the moving unit 20 are determined by giving a predetermined signal from the movement control unit 21 to the moving unit 20, so that the moving direction and the amount of movement of the side shift sensor 2 can be controlled.
[0014]
The movement control means 21 obtains a detection signal from the side shift sensor 2 or the side shift home sensor 3, determines a signal to be sent to the movement means 20, and moves the registration roll pair 1 in the axial direction, that is, a displacement of the sheet P. Control the amount of correction.
[0015]
FIG. 2 is a schematic diagram illustrating an example of the side shift sensor. The example shown in FIG. 2A is a side shift sensor 2 using a reflection type sensor. The side shift sensor 2 emits light to the sheet P, and detects the sheet P by receiving the light reflected by the sheet P. ing. That is, when the reflection type sensor detects reflected light, it detects that there is a sheet P, and when it does not detect reflected light, it detects that there is no sheet P.
[0016]
The example shown in FIG. 2B is a side shift sensor 2 in which a light emitting side sensor and a light receiving side sensor are separated, and a light emitting side sensor is provided on one side and a light receiving side sensor is provided on the other side with the position of the paper P therebetween. Are located. By emitting light from the light emitting side sensor toward the light receiving side sensor, if the light is blocked by the paper P and does not reach the light receiving side sensor, the presence of the paper P is detected. , It is detected that there is no paper P.
[0017]
The example shown in FIG. 2C is a side shift sensor 2 in which a light emitting sensor and a light receiving sensor are supported by U-shaped arms. Since the light emitting side sensor and the light receiving side sensor are supported by the U-shaped arms, the sensors can be easily installed while maintaining the alignment accuracy of each sensor.
[0018]
In this side shift sensor 2, the depth d of the U-shaped arm is a size that does not contact the U-shaped arm even if the side shift sensor 2 moves between the minimum size and the maximum size of the paper P. Keep it. This makes it possible to realize the movement control of the side shift sensor 2 described later.
[0019]
The side shift sensor 2 includes, in addition to the holding means such as the arms shown in FIGS. 2A to 2C described above, a sensor (reflective sensor, light receiving sensor, light emitting side) Before passing through the position of the sensor, any form may be used as long as the sensor can be moved to a position corresponding to the next sheet having a smaller size than the sheet to be conveyed.
[0020]
Next, the movement timing of the side shift sensor by the movement control means 21 will be described with reference to FIGS. First, as shown in FIG. 3 (1), the side shift sensor 2 is stopped at the home position (see the broken line in the figure).
[0021]
Next, as shown in FIG. 3 (2), the side shift sensor 2 is moved by a set distance from the home position according to the size of the sheet P being conveyed. In this state, when the sheet P is conveyed as shown in FIG. 3 (3) -1 and the sheet P is detected by the side shift sensor 2, as shown in FIG. 1 is moved along the left direction in the figure along the axial direction. Then, the movement is continued until the side shift sensor 2 stops detecting the sheet P.
[0022]
On the other hand, as shown in FIG. 4 (3) -2, when the side shift sensor 2 to which the sheet P has been conveyed does not detect the sheet P, as shown in FIG. The pair 1 is moved along the axial direction along the right direction in the figure. Then, this movement is continued until the side shift sensor 2 detects the sheet P.
[0023]
Regardless of the movement, the sheet P is misaligned so that the edge of the sheet P matches the position of the side shift sensor 2.
[0024]
Next, as shown in FIG. 5 (5), after the detection of the side shift sensor 2 and the correction of the positional deviation of the paper P due to the movement of the registration roll pair 1, before the paper P passes through the registration roll pair 1 ( For example, immediately after the correction is completed), the side shift sensor 2 is returned to the home position.
[0025]
Further, as shown in FIG. 5 (6), before the sheet P passes through the registration roll pair 1, the side shift sensor 2 is moved in accordance with the size of the next sheet P '. At this time, by invalidating the detection of the side shift sensor 2, it is possible to prevent the paper P being transported from being erroneously detected.
[0026]
Next, as shown in FIG. 5 (7), after the sheet P has passed the position of the side shift sensor 2, the side shift sensor 2 is made effective to detect the next sheet P '. The detection of the next sheet P ′ and the correction of the positional deviation are performed in the same manner as the sheet P.
[0027]
As described above, after the detection of one sheet P by the side shift sensor 2 and the displacement correction by the movement of the registration roll pair 1, the size of the next sheet P ′ is set before the paper P passes through the registration roll pair 1. By moving the side shift sensor 2 in accordance with the condition, the side shift sensor 2 can accurately detect the next sheet P ′ even if the gap between the sheet P and the next sheet P ′ is narrow, and Even if the transport speed is increased or the paper interval is narrowed, it is possible to accurately correct the positional deviation of continuously transported paper.
[0028]
Here, in the present embodiment, before the sheet P passes through the registration roll pair 1, the side shift sensor 2 is moved according to the size of the next sheet P ′. When the size of P ′ is small, the side shift sensor 2 is disposed inside the paper P.
[0029]
Therefore, as the side shift sensor 2 applied in the present embodiment, a reflection type sensor as shown in FIG. 2A and a light emitting side sensor and a light receiving side sensor as shown in FIG. If it is provided, there is no contact with the paper P. However, in the side shift sensor 2 in which the light emitting side sensor and the light receiving side sensor are provided at the tip of the U-shaped arm as shown in FIG. 2C, it is necessary to devise the depth d of the U-shaped arm. There is.
[0030]
That is, the paper P is provided with a depth d such that it does not contact the paper P even when the side shift sensor 2 moves from the detection position of the largest paper P to the detection position of the smallest paper P ′. Even if the side shift sensor 2 moves before passing through the registration roll pair 1, the paper P does not need to contact the side shift sensor 2.
[0031]
【The invention's effect】
As described above, the present invention has the following effects. That is, after the sheet is detected by the side shift sensor and the position of the sheet is corrected by the registration roll pair, the side shift sensor is moved according to the size of the next sheet before the sheet passes through the registration roll pair. In addition, even if the transport speed of the sheet is increased or the interval between the sheets is narrowed, the displacement of the next sheet can be immediately detected. As a result, it is possible to perform accurate paper position shift correction even in an image forming apparatus that pursues high productivity.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a paper position shift correction device according to an embodiment.
FIG. 2 is a schematic diagram illustrating an example of a side shift sensor.
FIG. 3 is a schematic diagram (part 1) illustrating timing of movement of a side shift sensor by the movement control means.
FIG. 4 is a schematic diagram (part 2) for explaining the movement timing of the side shift sensor by the movement control means.
FIG. 5 is a schematic diagram (part 3) illustrating timing of movement of the side shift sensor by the movement control means.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Register roll pair, 2 ... Side shift sensor, 3 ... Side shift home sensor, 10 ... Rotation drive means, 11 ... Shift drive means, 21 ... Movement control means

Claims (5)

A pair of registration rolls that transports the paper and moves the paper in a direction perpendicular to the transport direction,
A side shift sensor that detects a position along a direction perpendicular to the transport direction of the paper transported by the registration roll pair,
Moving means for moving the side shift sensor along a direction perpendicular to the sheet conveying direction according to the size of the sheet,
After performing position correction in the direction perpendicular to the paper transport direction by moving the registration roll pair based on the detection of the paper by the side shift sensor, the side shift sensor is used before the paper passes through the registration roll pair. And a movement control means for moving the sheet to a position corresponding to the size of the next sheet by the movement means. 2. The sheet misalignment correction apparatus according to claim 1, wherein the side shift sensor includes a reflection sensor that emits light toward a detection position of the sheet and detects the presence or absence of reflection of the light. 2. The sheet position deviation correcting device according to claim 1, wherein the side shift sensor includes a light emitting unit provided on one side with the sheet detection position therebetween, and a light receiving unit provided on the other side. . An image forming apparatus comprising the sheet positional deviation correcting device according to claim 1. Detecting means for detecting a position along a direction perpendicular to the transport direction of the transported sheet;
Moving means for moving the detecting means in a direction perpendicular to the sheet conveying direction in accordance with the size of the sheet,
Before the trailing end of the conveyed sheet passes the position of the detection unit, the detection unit can be moved to a position corresponding to the next sheet having a size smaller than the sheet to be conveyed by the movement unit. And a holding unit for holding the detection unit.

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