JP2017190202A - Conveyance device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conveyance device and an image forming apparatus capable of highly accurately detecting a positional deviation amount in a width direction of a recording medium conveyed in a predetermined conveying direction.SOLUTION: When a recording medium P is not conveyed to a position facing a CIS36 (contact image sensor), a reference plate 15 on which a white portion 15a (light reflecting portion) and a black portion 15b (low-light reflecting portion) are formed is moved by a moving mechanism to the position facing the CIS36 to detect data for use in shading correction and to detect a widthwise distance M between two light receiving elements 36c10 adjacent to each other across a boundary between adjacent sensor IC chips 36c1 (light receiving element group). When the recording medium P is conveyed to the position facing the CIS36 and a widthwise positional deviation amount is detected, the detected positional deviation amount is corrected by the widthwise distance M detected by the CIS36.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a conveying apparatus that conveys a recording medium, and an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine or an offset printing machine including the same.

  Conventionally, in an image forming apparatus such as a copying machine or a printer, a position in a width direction (a direction substantially perpendicular to the conveyance direction) of a recording medium conveyed in a predetermined conveyance direction (hereinafter referred to as “horizontal registration” as appropriate). Is detected by a contact image sensor (CIS), and the position in the width direction of the recording medium is corrected to a normal position based on the detection result (for example, patents). Reference 1).

  Specifically, in the image forming apparatus (conveyance apparatus) in Patent Document 1, a plurality of photosensors are arranged in parallel in the width direction so as to face the recording medium conveyed in a predetermined direction across the width direction. An image sensor (CIS) is installed. When the recording medium passes through the position of the contact image sensor, the position of the recording medium in the width direction is detected by the contact image sensor, and the amount of positional deviation in the width direction is obtained. Then, the lateral registration of the recording medium is corrected by moving the recording medium in the width direction so as to cancel out the obtained positional deviation amount in the width direction.

  The above-described conventional technique has a gap between adjacent light receiving elements (pixels) and light receiving elements (pixels) at the boundary between light receiving element groups (sensor IC chips) arranged in parallel in the width direction in the contact image sensor. Since the distance between the light receiving element (pixel) and the light receiving element (pixel) in each light receiving element group is not uniform, the accuracy of the positional deviation amount in the width direction of the recording medium detected by the contact image sensor is reduced. I was doing it. For this reason, the accuracy of the lateral registration correction of the recording medium corrected based on the detection result cannot be improved.

  The present invention has been made in order to solve the above-described problems, and can convey a positional deviation amount in the width direction of a recording medium conveyed in a predetermined conveyance direction with high accuracy, and Another object is to provide an image forming apparatus.

  The transport device according to the present invention is a transport device that transports a recording medium, and is disposed so as to extend in the width direction, and is positioned in the width direction of the recording medium that is transported in a transport direction substantially orthogonal to the width direction. A contact image sensor for detecting the amount of misalignment, a light reflecting portion for reflecting light, and a low light reflecting portion formed so that the reflectance of light is smaller than that of the light reflecting portion are formed. A reference plate and a moving mechanism for moving the reference plate from a retracted position not facing the contact image sensor to a facing position facing the contact image sensor, or from the facing position to the retracted position; The contact image sensor is reflected by the light source, the lens, and the recording medium that is emitted from the light source and faces the contact image sensor or the reference plate. A light receiving element group in which a plurality of light receiving elements formed so as to be capable of receiving light are arranged in the width direction, and a plurality of light receiving parts arranged in the width direction, and facing the contact image sensor When the recording medium is not conveyed to the position, the reference plate is moved from the retracted position to the facing position by the moving mechanism at a predetermined timing, and data used for shading correction of the contact image sensor is detected. In addition, the recording medium is transported to a position facing the contact image sensor by detecting a widthwise interval between the light receiving elements adjacent to each other at a boundary portion between the adjacent light receiving element groups. When the positional deviation amount in the width direction of the recording medium is detected, the contact image sensor is detected with respect to the detected positional deviation amount. Thus corrects the length of the sensed the width direction of the spacing.

  According to the present invention, it is possible to provide a transport apparatus and an image forming apparatus that can detect a positional deviation amount in the width direction of a recording medium transported in a predetermined transport direction with high accuracy.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. It is the schematic which shows a conveying apparatus. It is a top view which shows a part of conveying apparatus. It is a block diagram which shows the principal part of a conveying apparatus. It is a schematic top view which shows the principal part of a conveying apparatus. It is a figure which shows the state in which the holding member was supported on the flame | frame by the relay support member in the conveying apparatus. It is a block diagram which shows a two-stage spline coupling. The holding member is (A) the figure which operates in the width direction, (B) the figure which operates in the diagonal direction, and (C) the figure which operates in the width direction and the diagonal direction simultaneously. It is the schematic which shows operation | movement of a conveying apparatus. FIG. 10 is a schematic diagram illustrating an operation of the conveyance device following FIG. 9. It is a schematic sectional drawing which shows the state in which a recording medium passes the position of CIS. It is a bottom view which shows CIS. It is an enlarged view which shows the light-receiving part of CIS. It is a schematic block diagram which shows the moving mechanism of a reference | standard board. It is the schematic which shows the state which the reference | standard board moved to the opposing position with CIS with the moving mechanism. It is a schematic side view which shows the principal part of the moving mechanism of a reference | standard board. It is a graph which shows the output change of CIS. It is a figure which shows the method of calculating | requiring the accumulated position shift detection error using the movement amount of the reference | standard board detected by CIS. It is a figure which shows the method of correct | amending the position shift amount of the width direction detected by CIS. It is a schematic block diagram which shows the moving mechanism of the reference | standard board in the conveying apparatus in Embodiment 2 of this invention. It is the schematic which shows the state which the reference | standard board moved to the position facing CIS with the moving mechanism of FIG. 6 is a graph showing changes in CIS output according to the second embodiment. It is a schematic block diagram which shows the moving mechanism of a reference | standard board in the conveying apparatus in Embodiment 3 of this invention. It is the schematic which shows the state which the reference | standard board moved to the position facing CIS with the moving mechanism of FIG. 10 is a graph showing changes in CIS output in the third embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

<Embodiment 1>
The first embodiment of the present invention will be described in detail with reference to FIGS.
First, the overall configuration and operation of the image forming apparatus will be described with reference to FIG.
In FIG. 1, 1 is a copying machine as an image forming apparatus, 2 is a document reading unit that optically reads image information of a document D, and 3 is a photosensitive member that exposes light L based on the image information read by the document reading unit 2. An exposure unit for irradiating the drum 5, 4 is an image forming unit for forming a toner image (image) on the photosensitive drum 5, and 7 is a transfer for transferring the toner image formed on the photosensitive drum 5 to the recording medium P. Section (image forming section), 10 is a document transport section that transports a set document D to the document reading section 2, and 12 to 14 are sheet feeding sections (sheet feeding) in which a recording medium P (sheet) such as transfer paper is stored. Cassette) 20 is a fixing device for fixing an unfixed image on the recording medium P, 21 is a fixing roller installed in the fixing device 20, 22 is a pressure roller installed in the fixing device 20, and 30 is a recording medium P. A transport device 31 for transporting along the transport path, 31 is a transfer unit 7 (image Registration rollers (nip roller that serves as a timing roller) for conveying the recording medium P toward the forming unit) (horizontal resist skew correction roller) shows.

With reference to FIG. 1, an operation during normal image formation in the image forming apparatus will be described.
First, the document D is conveyed from the document table in the direction of the arrow in the drawing by the conveyance roller of the document conveyance unit 10 and passes over the document reading unit 2. At this time, the document reading unit 2 optically reads the image information of the document D passing above.
Then, the optical image information read by the document reading unit 2 is converted into an electric signal and then transmitted to the exposure unit 3 (writing unit). An exposure light L (laser light) based on the image information of the electrical signal is emitted from the exposure unit 3 toward the photosensitive drum 5 of the image forming unit 4.

On the other hand, in the image forming unit 4, the photosensitive drum 5 is rotated in the clockwise direction in the drawing, and image information is transferred onto the photosensitive drum 5 through a predetermined image forming process (charging process, exposure process, development process). An image (toner image) corresponding to is formed.
Thereafter, the image formed on the photosensitive drum 5 is transferred onto the recording medium P conveyed by the sandwiching roller 31 functioning as a registration roller in the transfer unit 7 as an image forming unit.

On the other hand, referring to FIGS. 1 and 2, the recording medium P conveyed to the transfer unit 7 (image forming unit) operates as follows.
First, one of the plurality of paper feeding units 12 to 14 of the image forming apparatus main body 1 is automatically or manually selected (for example, the paper feeding unit 12 provided in the main body 1 is selected. )
Then, the uppermost sheet of the recording medium P stored in the paper feed unit 12 is directed by the paper feed roller 41 toward the curved conveyance path where the first conveyance roller pair 42 and the second conveyance roller pair 43 are installed. Be fed.

  Thereafter, the recording medium P passes through the curved conveyance path through the position of the merging portion X (the portion where the conveyance paths from the two paper feeding units 13 and 14 installed outside the apparatus main body 1 merge). The third conveying roller pair 44 passes through the linear conveying path in which the aligning unit 51 is installed, and reaches the position of the sandwiching roller 31 constituting the aligning unit 51. Then, the skew feeding correction and the lateral registration correction are performed by the sandwiching roller 31 constituting the aligning unit 51, and further, the transfer unit is aligned with the timing in order to align with the image formed on the photosensitive drum 5. 7 (image forming unit).

After the transfer process, the recording medium P passes through the position of the transfer unit 7 and then reaches the fixing device 20 through the conveyance path. The recording medium P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 22, and the image is fixed by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22. The The recording medium P on which the image has been fixed is delivered from between the fixing roller 21 and the pressure roller 22 (a nip portion) and then discharged from the image forming apparatus main body 1.
Thus, a series of image forming processes is completed.

Here, referring to FIG. 2, the image forming apparatus 1 according to the first embodiment can feed the recording medium P from the three paper feeding units 12 to 14 toward the transfer unit 7 (image forming unit). It is configured.
Further, the conveyance roller pairs 42 to 44 (including a conveyance roller pair not provided with a reference numeral) installed in the conveyance device 30 are all drive rollers (rollers driven by a drive mechanism). A pair of rollers including a driven roller (a roller that is driven and rotated by frictional resistance with a driving roller), and is configured to be able to convey the recording medium P while being sandwiched between two rollers.

  Here, the transfer unit 7 (image forming unit) starts from the junction X where the conveyance path from the first sheet feeding unit 12 and the conveyance path from the second and third sheet feeding units 13 and 14 merge. As a transport path up to, a linear transport path formed in a substantially straight line along the transport direction of the recording medium P is provided. This linear conveyance path is formed by a linear conveyance guide plate 17 (see FIG. 11. The linear conveyance path 17 is installed so as to sandwich the front and back surfaces of the recording medium P to be conveyed). Conveying roller pair 44, CIS 36 (second detection means) as contact image sensor, skew detection sensor 35 (first detection means) as skew detection means, nipping roller 31 (alignment unit 51), auxiliary detection means A second skew detection sensor 37 (third detection means) is installed. Each of the third transport roller pair 44 and the sandwiching roller 31 is a roller pair composed of a driving roller and a driven roller, and transports the recording medium P while being sandwiched between the two rollers. The sandwiching roller 31 performs an alignment operation between skew correction (correction for a positional deviation in the oblique direction with respect to the conveyance direction) and lateral registration correction (correction for a positional deviation in the width direction). This will also function as the matching unit 51, which will be described in detail later.

Next, with reference to FIG. 2 to FIG. 19, the characteristic transport device 30 in the first embodiment will be described in detail.
Hereinafter, the configuration in the transport path from the junction X to the transfer unit 7 (image forming unit) and the operations performed there will be mainly described.
2 and 3, the conveyance device 30 includes a third conveyance roller pair 44, along a linear conveyance path of the recording medium P (a conveyance path from the merging portion X to the transfer portion 7). CIS 36 (contact image sensor), skew detection sensor 35 as skew detection means, clamping roller 31 (horizontal registration / skew correction roller) functioning as a registration roller as well as a registration unit 51, auxiliary detection means A second skew detection sensor 37 is installed.

Here, the sandwiching roller 31 is a roller pair having a roller portion divided into a plurality of parts in the width direction, and is a driving roller that is rotationally driven by a first motor 61 (see FIG. 4) as a first driving means. 31b and a driven roller 31a that rotates following the rotation of the driving roller 31b. The sandwiching roller 31 is formed so as to be able to transport the recording medium P by rotating in a state where the recording medium P is sandwiched.
In the first embodiment, a roller pair having a plurality of roller portions divided in the width direction is used as the sandwiching roller 31, but a roller having a roller portion that extends in the width direction without being divided in the width direction. Pairs can also be used.

In addition, the holding roller 31 is formed so as to be able to rotate in an oblique direction (in the direction of the broken line double arrow W in FIG. 3) around the support shaft 73 together with a holding frame 72 as a holding member. It is formed so that it can move in the direction of the broken line arrow S in FIG.
The clamping roller 31 rotates around the support shaft 73 together with the holding frame 72 on the basis of the detection result of the skew detection sensor 35 (skew detection means) to correct the skew of the recording medium P, or CIS 36. Based on the detection result of the (contact image sensor), it moves along the guide portion 71a together with the holding frame 72 to correct the lateral registration of the recording medium P.

Specifically, with reference to FIGS. 4 to 6, the sandwiching roller 31 (the driven roller 31 a and the driving roller 31 b) is rotatably supported by a holding frame 72 as a holding unit. The holding frame 72 (holding portion) is formed by forming a sheet metal in a substantially box shape, and has both ends in the width direction (the vertical direction in FIG. 2 and the left-right direction in FIGS. 4 to 6). The shaft portion of the pinching roller 31 (the driven roller 31a and the driving roller 31b) is inserted into the hole portion formed in the portion through a bearing. The holding frame 72 moves in the width direction together with the sandwiching roller 31 and rotates around the support shaft 73.
At one end in the width direction of the driving roller 31b, the driving roller 31b is fixedly installed on a bracket 69 in a frame (a main body frame 70, a base frame 71, a bracket 69 and the like are fixed by screw fastening). The first drive means (comprised of the first motor 61, gear trains 66, 67, etc.) is connected via a two-stage spline coupling 65. As a result, the rotational driving force of the first motor 61 fixed to the frames 69 to 71 of the transport device 30 is transmitted to the driving roller 31b via the gear trains 66 and 67 and the two-stage spline coupling 65, and the pinching roller 31 Is driven to rotate.
In addition, an encoder 96 for controlling the rotation speed and rotation timing of the pinching roller 31 (drive roller 31b) is installed on the other end side in the width direction of the drive roller 31b.

Here, as shown in FIG. 7, the two-stage spline coupling 65 includes a first spline gear 65a, a second spline gear 65b, an intermediate spline gear 65c, a guide ring 65d, and the like.
The first spline gear 65a is an external gear, and is rotatably held by a rotating shaft 68 (with a bracket 69 via a bearing) that rotates together with one gear 67 of the gear trains 66 and 67 of the first driving means. )).
The second spline gear 65 b is an external gear and is installed on the shaft portion of the drive roller 31 b of the pinching roller 31.
The intermediate spline gear 65c is an internal gear and extends in the width direction so as to mesh with the two spline gears 65a and 65b even if the clamping roller 31 (holding frame 72) moves (slides) in the width direction. Has been. Further, the two spline gears 65a and 65b are formed in a crown shape so as to mesh with the intermediate spline gear 65c even when the sandwiching roller 31 (holding frame 72) rotates in an oblique direction.
By using such a two-stage spline coupling 65, even if the clamping roller 31 rotates about the support shaft 73 in a substantially horizontal plane direction or slides in the width direction, the frames 69 to 71 of the main body. The driving force of the first motor 61 (first driving means) fixedly installed on the motor is reliably and accurately transmitted to the pinching roller 31 (driving roller 31b), and the pinching roller 31 is driven to rotate favorably. become.
The guide ring 65d is a substantially annular stopper member, and is provided in order to prevent the two spline gears 65a and 65b from moving relative to each other in the width direction and falling off the two-stage spline coupling 65. The spline gear 65c is installed at both ends in the width direction.

5 and 6, the holding frame 72 (holding member) has a free bearing 95 (ball transfer) as a relay support member installed on the frames 69 to 71 (base frame 71) of the apparatus. The frame 69 to 71 (base frame 71) are supported so as to be movable in both the width direction and the oblique direction (so that the plane perpendicular to the paper surface of FIG. 6 can be moved freely). Supported). In FIG. 4, the illustration of the free bearing 95 is omitted to make it easy to visually recognize other components.
Here, the free bearing 95 (ball transfer) is a known bearing in which a steel ball 95a (sphere) is inserted into the recess of the pedestal 95b, and the top of the steel ball 95a makes point contact with the bottom surface of the holding frame 72. It will be. Three or more free bearings 95 as relay support members are arranged so as to support the holding frames 72 at three or more positions with respect to the frames 69 to 71 (base frame 71) (this embodiment). 1 has four free bearings 95). In the first embodiment, as shown in FIG. 5, at positions corresponding to the four corners on the bottom surface of the holding frame 72 (positions at which the holding frame 72 can be contacted even if it slides or rotates to the maximum). In each case, a free bearing 95 is fixedly installed on the base frame 71.
In this way, by supporting the holding frame 72 with respect to the base frame 71 via the free bearing 95, even if the holding frame 72 moves relative to the base frame 71 in the surface direction, the friction generated thereby. Since the load can be made extremely small, lateral registration correction and skew correction (skew correction) to be described later are performed with high responsiveness and high accuracy.

Here, referring to FIG. 4, FIG. 5, etc., the holding frame 72 (holding member) is fitted into a guide portion 71a formed to extend in the width direction in the base frame 71 (main body frame). A supporting shaft 73 (stud) is provided.
Specifically, on the bottom surface of the holding frame 72, a support shaft 73 (stud) is erected downward at a position relatively close to the end of the drive side (right side in FIGS. 4 and 5). Is fixed by caulking or the like. On the other hand, on the ceiling surface of the base frame 71, a guide portion 71a (a substantially rectangular hole portion) is located at a position relatively close to the end portion on the driving side (on the right side in FIGS. 4 and 5). Is formed. Then, the support shaft 73 of the holding frame 72 is fitted into the guide portion 71a (hole portion) of the base frame 71 via a guide roller 76 (a roller-shaped member rotatably installed on the support shaft 73). It is formed to do. Then, the holding frame 72 slides in the width direction in conjunction with the movement of the support shaft 73 along the guide portion 71 a together with the holding roller 31, and rotates around the support shaft 73.
In the first embodiment, the guide portion 71a into which the support shaft 73 of the holding frame 72 is fitted is a substantially hole, but the guide portion 71a enables the operation of the holding frame 72 described above. For example, the guide part 71a can be formed in a substantially elongated hole shape, and the guide part 71a can be a groove part.

With such a configuration, the second driving means 63, 81 to 84, 98 installed on the base frame 71 (the main body frame) causes the holding frame 72 to be attached to the support shaft 73 based on the detection result of the skew detection sensor 35. By rotating about the center, the holding roller 72 and the holding roller 31 are rotated in an oblique direction.
Further, the holding frame 72 is moved by moving the support shaft 73 along the guide portion 71a based on the detection result of the CIS 36 by the third driving means 62, 74, and 97 installed on the base frame 71 (frame of the main body). At the same time, the clamping roller 31 is moved in the width direction.

Specifically, the second driving means is for rotating the holding frame 72 (the clamping roller 31) around the support shaft 73, and includes a second motor 63, a timing belt 98, a first cam 84, a first cam. It comprises a first tension spring 92 as an urging member, a lever member 81 (rotating lever), and the like.
The first tension spring 92 as the first urging member urges the holding frame 72 in an obliquely forward direction (clockwise around the support shaft 73 in FIG. 5). And the base frame 71.
The first cam 84 is held by the base frame 71 so as to be rotatable about the rotation support shaft 84a, and the holding frame 72 biased in the forward direction of the diagonal direction by the first tension spring 92 is reversed in the diagonal direction. It is pushed indirectly via the lever member 81 in the counterclockwise direction around the support shaft 73 in FIG. In other words, the second drive means is configured to push the holding frame 72 via the lever member 81.
The lever member 81 is held by the base frame 71 so as to be rotatable about a rotation support shaft 81a, and a cam follower 82 (first roller-shaped member) that contacts the first cam 84 is rotatably installed at one end thereof. On the other end side, an action roller 83 (second roller-shaped member) that abuts against the protrusion 72a of the holding frame 72 is rotatably installed (axially supported).
The second motor 63 is fixedly installed on the base frame 71. A timing belt 98 is wound around the drive pulley installed on the motor shaft of the second motor 63 and the driven pulley installed on the rotation support shaft 84 a of the first cam 84.

  With such a configuration, referring to FIG. 8B, when the second motor 63 is driven, the rotational driving force is transmitted to the first cam 84 via the timing belt 98, and the lever member 81 is moved. The holding frame 72 is pushed by the lever member 81 at the position of the protrusion 72 a by being pushed by the first cam 84 and pivoting about the rotation support shaft 81 a, and the spring force of the first tension spring 92 is increased. The holding frame 72 rotates to resist.

The first cam 84 and the lever member 81 (cam follower 82) are always in contact with each other by the spring force of the first tension spring 92, and the holding frame 72 (projecting portion 72a) and the lever member 81 ( It is always in contact with the action roller 83), and the rotation angle (posture in the rotation direction) of the holding frame 72 around the support shaft 73 depending on the rotation angle (posture in the rotation direction) of the first cam 84. Will be determined.
As described above, the cam follower 82 as the first roller-shaped member is installed at the contact position between the first cam 84 and the lever member 81, and the contact position between the holding frame 72 (protrusion 72 a) and the lever member 81 is set. By installing the action roller 83 as the second roller-shaped member, the frictional load generated at each contact position can be extremely reduced, so that skew correction (skew correction) is performed with high responsiveness and high accuracy. It will be.

In the first embodiment, as shown in FIG. 4, an encoder wheel 86 is installed on the rotation support shaft 84 a of the first cam 84, and an encoder sensor 87 is fixed at the position of the base frame 71 corresponding thereto. Then, the rotation angle (posture in the rotation direction) of the first cam 84 (holding frame 72) is adjusted and controlled by the control of the second motor 63 based on the detection of the encoder wheel 86 by the encoder sensor 87, and the recording medium P is skewed. Correction will be performed.
Here, the first cam 84 is formed so that its cam curve becomes a constant velocity cam curve. As a result, the amount of change in the rotation angle of the first cam 84 and the amount of change in the rotation angle of the holding frame 72 can be proportional to each other, so that the skew correction control of the recording medium P is performed with high accuracy. be able to.

On the other hand, the third driving means is for slidably moving the holding frame 72 (the sandwiching roller 31) in the width direction together with the support shaft 73 moving along the guide portion 71a. The second cam 74, the second tension spring 91 as the second urging member, and the like.
The second tension spring 91 as the second urging member is connected to the holding frame 72 and the base frame 71 so as to urge the holding frame 72 in the positive direction of the width direction (the left direction in FIG. 5). Has been.
The second cam 74 is held by the base frame 71 so as to be rotatable about the rotation support shaft 74a, and the holding frame 72 biased in the forward direction in the width direction by the second tension spring 91 is reversed in the width direction. (It is the right direction in FIG. 5). A cam follower 75 is installed (axially supported) on the support shaft 73 of the holding frame 72 at a position where it abuts on the second cam 74, and at a position where it abuts on the guide portion 71a (base frame 71), a guide roller 76 (roller) is provided. (Like member) is installed (axially supported).
The third motor 62 is fixedly installed on the base frame 71. A timing belt 97 is wound around the drive pulley installed on the motor shaft of the third motor 62 and the driven pulley installed on the rotation support shaft 74 a of the second cam 74.

  With this configuration, referring to FIG. 8A, when the third motor 62 is driven, the rotational driving force is transmitted to the second cam 74 via the timing belt 97, and the second cam 74 is driven. As a result, the holding frame 72 slides so as to resist the spring force of the second tension spring 91.

The second cam 74 and the support shaft 73 (cam follower 75) are always in contact with each other by the spring force of the second tension spring 91, and depending on the rotation angle of the second cam 74 (posture in the rotation direction). The moving distance (position in the width direction) of the holding frame 72 (support shaft 73) is determined.
As described above, since the second cam 74 and the support shaft 73 are in contact with each other via the cam follower 75 as a roller-shaped member, the friction load generated at the contact position can be extremely reduced. The resist correction is performed with high response and high accuracy.

In the first embodiment, as shown in FIG. 4, an encoder wheel 77 is installed on the rotation support shaft 74 a of the second cam 74, and an encoder sensor 78 is fixed at the position of the base frame 71 corresponding thereto. Then, the rotation angle (posture in the rotation direction) of the second cam 74 is adjusted and controlled by the control of the third motor 62 based on the detection of the encoder wheel 77 by the encoder sensor 78, and the recording medium P of the recording medium P by the sliding movement of the holding frame 72 is controlled. Lateral registration correction is performed.
Here, the 2nd cam 74 is formed so that the cam curve may become a constant velocity cam curve. As a result, the amount of change in the rotation angle of the second cam 74 and the amount of change in the movement distance of the holding frame 72 can be made proportional to each other, so that the lateral registration correction control of the recording medium P is performed with high accuracy. be able to.

FIG. 8C is a diagram illustrating an example of the operation of the holding frame 72 when the skew feeding correction and the lateral registration correction of the recording medium P described above are performed at the same time.
As shown in FIG. 8C, when the second motor 63 is driven to rotate the first cam 84, the lever member 81 is pushed by the first cam 84 and rotates around the rotation support shaft 81a. As a result, the holding frame 72 is pushed by the lever member 81 at the position of the protrusion 72 a, and the holding frame 72 rotates to resist the spring force of the first tension spring 92. At the same time, when the third motor 62 is driven and the second cam 74 is rotated, the holding frame 72 slides and moves against the spring force of the second tension spring 91 by the second cam 74. At this time, the action roller 83 of the lever member 81 pushes the protrusion 72a (holding frame 72) while moving on the surface of the protrusion 72a.

As described above, in the first embodiment, the support shaft 73 that is a rotation fulcrum fixed to the holding frame 72 that rotatably holds the pinching roller 31 is slid and moved. Operation and shift operation (slide movement) are possible. For this reason, it is not necessary to install either the second driving means for rotating the pinching roller 31 or the third driving means for shifting the pinching roller 31 on the holding frame 72, and it is fixed to the main body. It can be installed on the other frame (base frame 71). Accordingly, the structure that rotates and slides can be reduced in weight, so that the responsiveness of these operations can be improved, and the driving source of the second driving means and the third driving means (the second motor 63, The power of the third motor 62) can be reduced, and the size and cost of the apparatus can be reduced. In the first embodiment, the first driving means for rotationally driving the clamping roller 31 is also installed in the frame (bracket 69) of the apparatus, not in the holding frame 72, so that the above-described effects can be further ensured. Will be demonstrated.
Further, since the support shaft 73 is shifted and moved by the second cam 74, the contact point between the second cam 74 and the holding frame 72 to be moved becomes one point, and even if the support shaft 73 rotates, the second cam 74 rotates. The support shaft 73 can be smoothly moved along the guide portion 71 a while sliding on one point on the surface of the two cams 74. Further, since the first cam 84 is in contact with the lever member 81 to be rotated at one point, even if the holding frame 72 is shifted, the lever member 81 (holding is held while sliding one point on the surface of the first cam 84). The frame 72) can be rotated while being shifted smoothly.

The sandwiching roller 31 corrects the positional deviation amount of the recording medium in the oblique direction based on the detection result of the skew detection sensor 35 while transporting the recording medium P while sandwiching the recording medium P. That is, the sandwiching roller 31 functions as means for performing skew correction (skew correction) of the recording medium P by displacing the recording medium P conveyed in the conveyance path in an oblique direction.
Further, the nipping roller 31 corrects the positional displacement amount of the recording medium P in the width direction based on the detection result of the CIS 36 (contact image sensor) while transporting the recording medium P in the nipped state. In other words, the pinching roller 31 also functions as means for correcting the lateral registration of the recording medium P by displacing the recording medium P conveyed in the conveyance path in the width direction.

  Here, the third transport roller pair 44 is installed at a position upstream of the sandwiching roller 31 (upstream in the transport direction). The third conveying roller pair 44 is formed so as to be able to convey the recording medium P by rotating in a state in which the recording medium P is sandwiched, and is separated so as to be able to switch between a state in which the recording medium P is sandwiched and a state in which the recording medium P is not sandwiched. It is a pair of conveyance rollers formed so as to be possible. When the recording medium P reaches the position of the sandwiching roller 31 and is sandwiched and transported by the sandwiching roller 31, the third transport roller pair 44 is switched from the state in which the recording medium P is sandwiched to the state in which it is not sandwiched. become.

Further, in the first embodiment, the sandwiching roller 31 is a pair of conveyance rollers that is disposed at a position upstream of the conveyance path with respect to the transfer unit 7 (image forming unit) and also functions as a registration roller. The recording medium P (the recording medium P after the skew feeding correction and the lateral registration correction are performed by the clamping roller 31 itself) is conveyed toward the image forming unit by rotating in a state where the recording medium P is sandwiched. .
Here, the first motor 61 that rotationally drives the pinching roller 31 (drive motor roller 31b) is a drive motor with variable rotation speed, and is formed so that the conveyance speed of the recording medium P can be varied. When the timing at which the recording medium P is conveyed to the position of the nipping roller 31 is detected by the paper detection sensor (photo sensor) (the recording medium P is conveyed to the position of the nipping roller 31 and the nipping roller 31 records the recording medium). When a state in which P is pinched is detected), the desired lateral registration correction and skew correction are performed by the pinching roller 31, and further, the conveyance by the pinching roller 31 is performed based on the detection result (detection timing) of the paper detection sensor. The speed is variable. That is, the conveyance speed by the nipping roller 31 is set so that the timing at which the recording medium P is conveyed to the transfer unit 7 by the nipping roller 31 and the timing at which the image formed on the photosensitive drum 5 reaches the transfer unit 7 are matched. (The conveyance timing of the recording medium P conveyed toward the image forming unit is adjusted). Thus, the image can be transferred to a desired position on the recording medium P while the lateral registration correction and the skew feeding correction of the recording medium P are performed without stopping the conveyance of the recording medium P by the sandwiching roller 31.
Note that the clamping roller 31 does not cause distortion in the image transferred onto the recording medium P due to a difference in linear velocity between it and the photosensitive drum 5 immediately after the leading edge of the recording medium P reaches the image forming unit. Thus, the conveyance speed is varied (the conveyance speed is varied so that the linear velocity ratio with respect to the photosensitive drum 5 is 1).

The skew detection sensor 35 serving as the skew detection means detects a positional deviation amount (skew amount) in the oblique direction of the recording medium P transported in the transport path.
Specifically, referring to FIG. 3, the skew detection sensor 35 is upstream of the conveyance path (conveyance direction) with respect to the sandwiching roller 31 and is downstream of the conveyance path with respect to the third conveyance roller pair 44. Is installed. The skew detection sensor 35 is two photosensors (consisting of a light emitting element such as an LED and a light receiving element such as a photodiode) installed at positions equidistant from the center position in the width direction. The skew amount β (skew amount) of the recording medium P is detected by detecting the deviation of the timing when the leading end of the recording medium passes. In the first embodiment, based on the detection result of the skew detection sensor 35, skew correction is performed while the recording medium P is sandwiched and conveyed by the sandwiching roller 31.
As a specific example, referring to FIG. 3, the recording medium P is only in the positive direction (the positive direction of the rotation direction) by an angle β with respect to the reference position indicated by the alternate long and short dashed line (the normal position without skew). When the skew detection state is detected by the skew detection sensor 35, the control unit sets the positional deviation amount β as a correction amount, and the holding roller 31 (holding frame) while the recording medium P is held by the holding roller 31. 72) is rotated by an angle β in the reverse direction (the reverse direction of the rotation direction and the clockwise direction in FIG. 3).

Referring to FIG. 3, the CIS 36 as a contact image sensor is on the upstream side of the conveyance path (conveyance direction) with respect to the sandwiching roller 31 and on the downstream side of the conveyance path with respect to the third conveyance roller pair 44. Is installed. The CIS 36 includes a plurality of photosensors (consisting of a light emitting element such as an LED and a light receiving element such as a photodiode) arranged in the width direction, and is a side end portion on one end side in the width direction of the recording medium P. By detecting the position of Pa (edge portion), the shift amount of the lateral resist is detected. That is, the CIS 36 detects the amount of positional deviation in the width direction of the recording medium P that is transported in the transport path of the transport device 30. Then, based on the detection result of the CIS 36, the lateral registration correction by the sandwiching roller 31 is performed.
In the first embodiment, as shown in FIG. 3, the CIS 36 is installed over the entire width direction, and the positions of the side end portions of the both ends in the width direction of the recording medium P (or the entire width direction of the recording medium P). However, it is also possible to detect the position of the side edge portion Pa on one end side in the width direction of the recording medium P by installing the CIS 36 only on one end side in the width direction.

Then, based on the detection result of the CIS 36, the holding roller 31 (holding frame 72) is moved in the width direction while the recording medium P is held and transported by the sandwiching roller 31, and the recording medium P transported in the transport path is detected. The positional deviation (lateral registration) in the width direction is corrected.
As a specific example, referring to FIG. 3, the recording medium P is positioned at one end side in the width direction (below the lower side of FIG. When the CIS 36 detects that the position is shifted by the distance α, the control unit sets the position shift amount α as a correction amount, and the recording medium P is sandwiched and conveyed by the sandwiching roller 31. The roller 31 (holding frame 72) is moved by the distance α to the other end in the width direction (upward in FIG. 3).

Thus, in the first embodiment, the clamping roller 31 rotates in an oblique direction based on the detection result of the skew detection sensor 35 while holding the recording medium P without stopping the conveyance of the recording medium P. By moving, the positional deviation amount of the recording medium P in the oblique direction is corrected, and the positional deviation amount in the width direction of the recording medium P is corrected by moving in the width direction based on the detection result of the CIS 36. That is, in the first embodiment, the skew amount of the recording medium P is detected by the skew detection sensor 35 in a state where the pinching roller 31 is rotated so that the recording medium P can be conveyed, and the recording medium P is detected based on the detection result. Next, the lateral registration correction of the recording medium P is detected by the CIS 36, and the lateral registration correction of the recording medium P is performed based on the detection result.
As a result, the productivity of the apparatus can be significantly improved as compared with the case where the conveyance of the recording medium P is stopped and the skew feeding correction and the lateral registration correction are separately performed. Further, when skew correction or lateral registration correction is performed, there is no difference in linear velocity between a plurality of roller portions installed in the width direction in the pinching roller 31, so that the recording medium P having a low friction coefficient on thin paper or the surface. Even when the paper is passed, the recording medium P is not bent or slipped.
A more detailed configuration and operation of the CIS 36 (contact image sensor) will be described later with reference to FIGS.

  Here, in the first embodiment, the sandwiching roller 31 sandwiches the recording medium P so as to correct the positional displacement amount of the recording medium P in the oblique direction based on the detection result of the first skew detection sensor 35. After rotating from a reference position (a position corresponding to a normal position with no positional deviation in the oblique direction) to pinch the recording medium P, the recording medium P is rotated to return to the reference position and detected by the CIS 36. Before the recording medium P is held, the width from the reference position (the position corresponding to the normal position without the positional deviation in the width direction) is corrected so that the positional deviation amount in the width direction of the recording medium P is corrected based on the result. After moving in the direction and sandwiching the recording medium P, the recording medium P is moved in the width direction so as to return to the reference position.

Then, the positional displacement amount in the width direction and the oblique direction of the recording medium P after the positional displacement amount in the width direction and the oblique direction is corrected by the sandwiching roller 31 is detected by the auxiliary detection means, and recording is performed based on the detection result. The positional deviation amount of the medium P in the width direction and the oblique direction is further corrected.
Specifically, a position (width) separated in the width direction is downstream of the conveyance path (conveyance direction) with respect to the sandwiching roller 31 and upstream of the conveyance path with respect to the transfer roller 7 as the downstream conveyance roller. A second skew detection sensor 37 (auxiliary detection means) comprising two photosensors arranged at equal intervals from the center position in the direction is installed. The second skew detection sensor 37 is configured in substantially the same manner as the first skew detection sensor 35 except that the installation position is different.
This second skew detection sensor 37 and the CIS 36 that also functions as a detection means for detecting the positional deviation amount in the width direction recorrect (finely adjust) the lateral registration correction and skew correction of the recording medium P. It functions as auxiliary detection means (third detection means).
Then, the sandwiching roller 31 rotates from the reference position described above while sandwiching the recording medium P so as to further correct the positional displacement amount of the recording medium P in the oblique direction based on the detection result of the second skew detection sensor 37. In addition, the recording medium P is moved in the width direction from the reference position in a state where the recording medium P is sandwiched so as to further correct the positional deviation amount in the width direction of the recording medium P based on the detection result of the CIS 36.

More specifically, the second skew detection sensor 37 is located at a position downstream of the sandwiching roller 31 and is displaced in the oblique direction with respect to the recording medium P that is skew-corrected while being sandwiched and conveyed by the sandwiching roller 31 ( (Skew amount) is detected. Similar to the first skew detection sensor 35, the second skew detection sensor 37 uses two photosensors disposed at positions separated in the width direction to shift the timing at which the leading end of the recording medium P passes. By detecting this, the skew amount β (skew amount) of the recording medium P is detected. Then, in the same manner as the skew correction based on the detection result of the first skew detection sensor 35 described above, the recording medium P is sandwiched by the sandwiching roller 31 based on the detection result of the second skew detection sensor 37. Skew correction is performed while transporting.
Further, the CIS 36 functions as a detection unit (second detection unit) that detects a positional deviation amount in the width direction of the recording medium P, and also functions as an auxiliary detection unit, and is positioned upstream of the sandwiching roller 31. Thus, the positional deviation amount in the width direction with respect to the recording medium P subjected to the lateral registration correction while being sandwiched and conveyed by the sandwiching roller 31 is further detected. The CIS 36 functioning as the auxiliary detection means detects the position of the lateral edge Pa (edge part) at both ends in the width direction of the recording medium P in the same manner as when functioning as the second detection means. Detect. Then, similarly to the lateral registration correction based on the detection result of the CIS 36 as the second detection means described above, the recording is performed by the sandwiching roller 31 based on the detection result of the CIS 36 as the auxiliary detection means (third detection means). Lateral registration correction is performed while the medium P is sandwiched and conveyed.

As described above, based on the detection result before the recording medium P is sandwiched by the sandwiching roller 31, the lateral registration correction and the skew feeding correction are performed once while the recording medium P is sandwiched and conveyed by the sandwiching roller 31, and then the assisting operation is performed. Based on the detection result of the detection means, the lateral registration correction and the skew feeding correction are performed again while the recording medium P is sandwiched and conveyed by the sandwiching roller 31 when the recording medium P enters the nip of the sandwiching roller 31. A slight misalignment or skew of the lateral resist may occur due to the shock, and a slight misalignment or skew of the lateral resist may occur when the roller portion of the pinching roller 31 is eccentric or improperly assembled. This is because a line may occur.
On the other hand, in the first embodiment, based on the detection result before being sandwiched by the sandwiching roller 31, the lateral registration correction and the skew feeding correction are performed once while the recording medium P is sandwiched and conveyed by the sandwiching roller 31. After that, the lateral registration correction and the skew correction are performed again while the recording medium P is being held and conveyed by the holding roller 31 based on the detection result of the auxiliary detection means after being held by the holding roller 31. The possibility as described above is limited, and the lateral registration correction and the skew correction can be performed with higher accuracy.

Here, in the first embodiment, when the CIS 36 is caused to function as auxiliary detection means as described above, the positional deviation in the width direction of the recording medium P is performed by feedback control based on the continuously detected CIS 36 detection result. It is preferable to move the pinching roller 31 in the width direction from the reference position in a state where the recording medium P is pinched so as to further correct the amount. That is, until the recording medium P reaches the image forming portion (transfer nip), the position shift of the lateral resist is continuously detected by the CIS 36, and on the one end side in the width direction of the recording medium P based on the detection result. It is preferable to continue re-correction of the lateral resist with good responsiveness so that the position of the end portion Pa (edge portion) coincides with the normal position (the position where the lateral resist is not misaligned).
By performing such control, lateral resist correction with higher accuracy can be performed.

Hereinafter, an example of the operation of the transport apparatus 30 configured as described above will be described in detail with reference to FIGS. 9 and 10.
9 (A1) to (C1) and FIGS. 10 (A1) to (B1) are top views showing the operation of the conveying device 30 in the order shown in FIGS. 9 (A2) to (C2). FIGS. 10A2 to 10B2 are side views of the transfer device 30 corresponding to the operations of FIGS. 9A1 to 9C1 and 10A1 to 10B1, respectively.
First, as shown in FIGS. 9A1 and 9A2, the recording medium P fed from the paper feeding unit 12 is nipped and conveyed toward the position of the nipping roller 31 by the third conveying roller pair 44. (Conveyance in the direction of white arrow). At this time, the sandwiching roller 31 has a rotation direction position at a first reference position (a normal position corresponding to the recording medium P without skew), and a width direction position at a second reference position (horizontal). It is a normal position corresponding to the recording medium P with no registration position misalignment).
Then, when the recording medium P reaches the position of the CIS 36, the lateral registration positional displacement amount α of the recording medium P is detected by the CIS 36. Further, when the recording medium P reaches the position of the skew detection sensor 35, the skew detection sensor 35 detects the skew amount β of the recording medium P. Note that the amount of positional deviation detected directly by the CIS 36 is in a state where the recording medium P is skewed, so that the positional deviation is detected from the detection result detected by the skew detection sensor 35 and the position of the CIS 36. Based on the distance to the position of the row detection sensor 35, etc., the position registration amount α of the lateral registration when there is no skew is obtained by the calculation unit (control unit).

Thereafter, as shown in FIGS. 9B1 and 9B2, the sandwiching roller 31 and the holding member 72 center the shaft portion 73 in the same inclination direction in accordance with the skew amount β detected by the skew detection sensor 35. Is rotated from the first reference position by an angle β, and is shifted from the second reference position by the distance α in the same width direction in accordance with the positional deviation amount α detected by the CIS 36.
Then, as shown in FIGS. 9C1 and 9C2, immediately before the leading end of the recording medium P reaches the sandwiching roller 31, the rotational drive of the sandwiching roller 31 (rotation drive in the direction of the arrow in the figure) is started. Then, when the recording medium P is nipped and conveyed by the nipping roller 31, the third conveying roller pair 44 moves away from the conveying path so that the recording medium P is not nipped (indicated by the solid arrow). Note that the timing at which the leading end of the recording medium P reaches the pinching roller 31 is the timing at which the leading end of the recording medium P is detected by the skew detection sensor 35 or the CIS 36, the conveyance speed of the recording medium P, and the skew detection sensor 35. Alternatively, the calculation unit (control unit) can determine the distance from the position of the CIS 36 to the position of the pinching roller 31.

Then, as shown in FIGS. 10A1 and 10A2, the sandwiching roller 31 has a shaft portion so as to cancel the skew amount β detected by the skew detection sensor 35 while sandwiching and transporting the recording medium P. While rotating so as to return to the first reference position around 71a, it moves in the width direction so as to return to the second reference position so as to cancel out the positional shift amount α detected by the CIS 36.
Then, as shown in FIGS. 10B1 and 10B2, when the corrected recording medium P reaches the position of the second skew detection sensor 37 (auxiliary detection means), recording is performed by the second skew detection sensor 37. The skew amount β ′ of the medium P is detected. Further, the lateral registration positional displacement amount α ′ of the recording medium P is continuously detected by the CIS 36 in which the corrected recording medium P functions as auxiliary detection means. The sandwiching roller 31 has a holding member 72 and a first angle β ′ about the shaft portion 71a in a different tilt direction (reverse direction) according to the skew amount β ′ detected by the second skew detection sensor 37. While rotating from the reference position, it is shifted from the second reference position by a distance α ′ in a different width direction (reverse direction) in accordance with the positional shift amount α ′ continuously detected by the CIS 36.
In this way, the recording medium P is conveyed toward the transfer roller 7 (image forming unit) while performing skew correction and lateral registration correction again. At this time, the number of rotations of the nipping roller 31 (the conveyance speed of the recording medium P until reaching the transfer roller 7) is varied so as to match the timing on the image on the photosensitive drum 5.

Then, as shown in FIGS. 10C1 and 10C2, the recording medium P is conveyed toward the transfer roller 7 (image transfer unit), and the image is transferred to a desired position on the recording medium P. become. Then, the third conveying roller pair 44 that has been in the separated state is returned to the abutting state (in the state of FIG. 9A2) to assist the conveyance of the recording medium P by the sandwiching roller 31, and next. In preparation for the transport operation of the recording medium P to be transported.
Thereafter, when the rear end of the recording medium P passes the position of the sandwiching roller 31, the sandwiching roller 31 prepares for the first reference position and the second registration position in preparation for skew correction and lateral registration correction of the recording medium P to be transported next. It will be returned to the reference position.

Here, the CIS 36 as a contact image sensor will be described in more detail with reference to FIGS.
As described above with reference to FIG. 3 and the like, the CIS 36 (contact image sensor) is aligned in the width direction (vertical direction in FIG. 13 in the horizontal direction). The CIS 36 detects the amount of positional deviation in the width direction of the recording medium P that is transported in the transport direction substantially orthogonal to the width direction.
Here, referring to FIG. 11 and the like, the CIS 36 includes a light source 36a (light emitting unit), a lens 36b, a light receiving unit 36c, and the like, as is well known. Then, the light emitted from the light source 36a is irradiated toward the recording medium P (or a reference plate 15 described later), and the light reflected on the surface is incident on the light receiving unit 36c via the lens 36b. It will be. In the first embodiment, among the linear conveyance guide plates 17 respectively disposed above and below the conveyance path for guiding the recording medium P to the position of the CIS 36, the upper linear conveyance guide plate 17 (opposite the CIS 36). In order to enable light irradiation from the CIS 36 to the recording medium P (or a reference plate 15 to be described later) and reception of the reflected light, a contact glass 16 (transparent glass) is used. is set up.
Referring to FIG. 12, in the light receiving portion 36c of the CIS 36, a plurality of sensor IC chips 36c1 as a light receiving element group are arranged in the width direction. Further, referring to FIG. 13, the sensor IC chip 36c1 (light receiving element group) can receive light emitted from the light source 36a and reflected by the recording medium P (or a reference plate 15 described later) facing the CIS 36. A plurality of light receiving elements 36c10 formed in the above are arranged in parallel in the width direction. The light receiving element 36c10 is a minimum unit as a so-called light receiving element, and its number affects the resolution of the CIS 36. Therefore, the light receiving element 36c10 is abbreviated as “pixel”.

In the CIS 36 configured as described above, the light receiving element 36c10 in the range from where to where among the plurality of light receiving elements 36c10 (pixels) arranged in parallel in the width direction receives the reflected light, and the range from where to where Depending on whether the light receiving element 36c10 did not receive the reflected light, the range in the width direction of the recording medium P is detected, and the positional deviation amount in the width direction is obtained.
However, as shown in FIG. 13, at the boundary between the sensor IC chips 36c1 arranged side by side in the width direction in the CIS 36, the distance M between the adjacent light receiving elements 36c10 and 36c10, and the light reception in each sensor IC chip 36c1. The interval N between the element 36c10 and the light receiving element 36c10 is not uniform, and the former interval M is often larger than the latter interval N for manufacturing reasons (M> N).
In addition, for each sensor IC chip 36c1 (light receiving element group), the interval N between the adjacent light receiving elements 36c10 and 36c10 is almost uniform, whereas the adjacent sensor IC chip 36c1 and sensor IC chip 36c1. The spacing M between the light receiving elements 36c10 disposed at the boundary between the two is low in uniformity.
For this reason, the accuracy of the positional deviation amount in the width direction of the recording medium P detected by the CIS 36 is lowered, and the accuracy of the lateral registration correction of the recording medium P that is corrected based on the detection result cannot be increased. .
In order to solve such a problem, in the first embodiment, the detection result of the CIS 36 is corrected using the reference plate 15 (see FIGS. 3 and 14 and the like).

Referring to FIGS. 3 and 14, the reference plate 15 is formed so that the length in the width direction is shorter than the length in the width direction of the CIS 36, and is arranged in parallel to the CIS 36. It is a shaped member. The reference plate 15 has, on its surface, a white portion 15a as a light reflecting portion that reflects light, and a low-light reflecting portion formed so that the reflectance of light is smaller than that of the white portion 15a (light reflecting portion). As a black portion 15b. In the first embodiment, the white portion 15a (light reflecting portion) and the black portion 15b (low light reflecting portion) are formed so as to be adjacent to each other in the width direction. In particular, in the present embodiment, the white portion 15a as the light reflecting portion is formed in white so that the light reflectance is extremely high, and the black portion 15b as the low light reflecting portion has an extremely high light reflectance. It is formed in black so as to be low.
The reference plate 15 is moved in the width direction (in the direction of the double black arrow in FIG. 3 and up and down in FIGS. 14 and 15) by moving mechanisms 61, 151, 161 to 164, and 170 to 172 shown in FIGS. It is configured to be movable in the direction that is perpendicular to the paper surface of FIG. Specifically, the moving mechanisms 61, 151, 161 to 163, and 170 to 172 move the reference plate 15 from the retracted position (the position shown in FIGS. 3 and 14) that does not face the CIS 36 (contact image sensor). It is moved to the facing position facing the CIS 36 or from the facing position to the retracted position. More specifically, the moving mechanisms 61, 151, 161 to 163, and 170 to 172 start moving the reference plate 15 from a retracted position that is separated in the width direction with respect to the CIS 36, and from the one end side in the width direction of the CIS 36 to the width direction. The opposite position is moved toward the other end side.

Specifically, referring to FIGS. 14 to 16, the moving mechanism that moves the reference plate 15 transmits or blocks the rotational driving force from the first motor 61 that rotates the pinching roller 31. And a motion conversion mechanism 160 that converts the rotational driving force transmitted from the first motor 61 into a linear motion.
The motion conversion mechanism 160 is mainly composed of a ball screw mechanism including a screw shaft 161 arranged so as to extend in the width direction and a ball nut 162 screwed into the screw shaft 161. The ball nut 162 is integrally provided with a support member 163 that supports the reference plate 15.
As shown in FIG. 16, the support member 163 extends in the horizontal direction along the horizontal portion 163 a (the linear conveyance guide plate 17) provided on the ball nut 162 disposed below the linear conveyance guide plate 17. And a vertical portion 163b that rises upward from the horizontal portion 163a through an opening formed in the lower linear conveyance guide plate 17. The reference plate 15 is attached to the upper end portion of the vertical portion 163 b and is disposed so as to be close to the vicinity of the lower surface of the contact glass 16. A sliding portion 163c configured to sandwich the guide plate 164 is provided at the end of the horizontal portion 163a opposite to the ball nut 162 side. The guide plate 164 is disposed below the lower linear conveyance guide plate 17 and is disposed so as to extend in the width direction.

As shown in FIG. 14, the clutch mechanism 150 is provided with a clutch gear 151 for transmitting or interrupting the driving force of the first motor 61 to the screw shaft 161. The clutch gear 151 reciprocates in the direction of the rotation axis thereof, so that the gear 170 provided on the rotation shaft of the first motor 61 and the gear 172 engaged with the gear 171 provided at the end of the screw shaft 161 are On the other hand, it is configured to be connected or disconnected.
In the first embodiment, a third motor 62 (refer to FIG. 4) of third driving means for moving the holding frame 72 in the width direction is used as a drive source for moving the clutch gear 151 in the rotation axis direction. Yes. Specifically, the driving force from the third motor 62 is transmitted to the clutch gear 151 via the timing belt 97, the second cam 74, and the link mechanism 152. The link mechanism 152 includes a first link member 153 that extends in the radial direction from the rotation support shaft 74a of the second cam 74, and an engagement portion that is formed in a protruding shape at a distal end portion that extends the rotation shaft of the clutch gear 151 in the width direction. And a second link member 154 having 154a. A tension spring 155 is connected to the rotation shaft of the clutch gear 151. By this tension spring 155, the clutch gear 151 is urged in a direction in which the connection with the counterpart gears 170, 172 is released.

With this configuration, when the third motor 62 of the first drive mechanism 38 is driven from the state shown in FIG. 14 and the second cam 74 is rotated clockwise as shown in FIG. The distal end portion of the first link member 153 comes into contact with the engaging portion 154a of the second link member 154, and the clutch gear 151 is pushed downward by the first link member 153 so as to resist the urging force of the tension spring 155. Is done. As a result, the clutch gear 151 is coupled to the gears 170 and 172 so that the driving force can be transmitted from the first motor 61 of the clamping roller 31 to the screw shaft 161.
When the first motor 61 is driven in this state, the driving force is transmitted to the screw shaft 161, and the screw shaft 161 rotates in a predetermined direction. Thereby, the ball nut 162 moves along the screw shaft 161, and the reference plate 15 moves from the retracted position shown in FIG. 14 to the facing position shown in FIG. At this time, in the process in which the reference plate 15 moves from one end side in the width direction of the CIS 36 to the other end side in the width direction, reference data is acquired for each light receiving element 36c10 (pixel) of the CIS 36, and the maximum value of the acquired reference data is set. It will be used to perform shading correction. In the first embodiment, the reference data used in the shading correction is detected (acquired) as described above, and the light receiving elements 36c10 and 36c10 adjacent to each other at the boundary between the adjacent light receiving element groups 36c1 are detected. The interval in the width direction is detected, which will be described in detail later.

Thereafter, when the first motor 61 is rotated in the reverse direction, the screw shaft 161 rotates in the direction opposite to the direction described above, and accordingly, the ball nut 162 moves in the direction opposite to the direction described above. (The movement is from the top to the bottom of FIGS. 14 and 15). Finally, the reference plate 15 is returned from the facing position shown in FIG. 15 to the retracted position shown in FIG.
Further, after the reference plate 15 is reciprocated as described above, the third motor 62 of the third driving means is rotated in the reverse direction, and the second cam 74 is rotated in the counterclockwise direction in the drawing from the state shown in FIG. As a result, the clutch gear 151 is moved upward in the drawing by the urging force of the tension spring 155, and the connection between the clutch gear 151 and the gears 170 and 172 on the other side is released. In such a state (the state shown in FIG. 14), the driving force from the first motor 61 is transmitted to the screw shaft 161 even when the nipping roller 31 is rotationally driven when the recording medium P is conveyed. Therefore, the reference plate 15 does not move from the retracted position and does not hinder the conveyance of the recording medium P or the lateral registration detection by the CIS 36.

Here, in the first embodiment, the moving mechanism configured as described above is used to move the recording medium at a predetermined timing when the recording medium is not conveyed to a position facing the CIS 36 (contact image sensor). The mechanism moves the reference plate 15 from the retracted position shown in FIGS. 3 and 14 to the facing position shown in FIG. 15 to detect (acquire) data (reference data) used in the shading correction of the CIS 36 and to detect adjacent sensors. An interval M in the width direction between the light receiving elements 36c10 and 36c10 adjacent to each other at the boundary between the IC chips 36c1 (light receiving element groups) is detected (hereinafter, this detection is appropriately referred to as “interval detection”). .
Specifically, in the present embodiment, detection related to shading correction using such a reference plate 15 and interval detection are performed during a warm-up operation after the main power supply of the apparatus main body 1 is turned on.

When the normal image forming operation is started and the recording medium P is transported to a position facing the CIS 36 (contact image sensor) and the positional deviation amount in the width direction of the recording medium P is detected by the CIS 36. For the detected positional deviation amount, the length of the interval in the width direction detected by the CIS 36 at the time of interval detection is corrected.
That is, in the CIS 36, the light receiving element 36c10 in the range from where to where among the plurality of light receiving elements 36c10 (pixels) arranged in parallel in the width direction receives the reflected light, and the light receiving element 36c10 in the range from where to the reflected light. The range in the width direction of the recording medium P is determined depending on whether the light is not received. At that time, the boundary between the adjacent sensor IC chips 36c1 is set at the interval N between the light receiving elements 36c10 in each sensor IC chip 36c1. The portion of the interval (joint) between the light receiving elements 36c10 (the difference from the interval N described above) is taken into account (corrected).

  By performing such correction control, the light receiving element 36c10 and the light receiving element 36c10 that are adjacent to each other at the boundary between the sensor IC chips 36c1 arranged in parallel in the width direction in the CIS 36, as described above with reference to FIG. Even if the distance M between the light receiving element 36c10 and the light receiving element 36c10 in each sensor IC chip 36c1 is not uniform, or the former distance M itself is not uniform, it is detected by the CIS 36. Since the amount of positional deviation in the width direction of the recording medium P can be corrected with high accuracy, the accuracy of lateral registration correction of the recording medium P that is adjusted based on the detection result can be reliably increased.

In particular, in the first embodiment, when the detection related to the shading correction is performed as described above, the CIS 36 (contact image sensor) detects the above-described interval M in the width direction and receives light in the CIS 36. Accumulated misalignment detection errors due to the position in the width direction for each element 36c10 are detected. That is, of the plurality of light receiving elements 36c10 (pixels) arranged side by side in the width direction, the cumulative positional deviation amount at the position of the Kth light receiving element 36c10 from one end side is determined for all the light receiving elements 36c10. Desired.
Then, when the normal image forming operation is started and the recording medium P is conveyed to the position facing the CIS 36 and the positional deviation amount in the width direction of the recording medium P is detected, the detected positional deviation amount. On the other hand, the length of the interval M in the width direction detected by the CIS 36 and the accumulated positional deviation detection error are corrected.
By performing such control, the positional deviation amount in the width direction of the recording medium P detected by the CIS 36 can be corrected with higher accuracy.

More specifically, the moving mechanism described above with reference to FIG. 14 and the like starts the movement of the reference plate 15 from the retracted position separated in the width direction with respect to the CIS 36, and the movement amount detecting means detects the width of the reference plate 15. While the amount of movement in the direction is detected, the opposite position is moved from one end in the width direction toward the other end in the width direction.
As the moving amount detecting means, an encoder 96 (see FIG. 4) installed in the first motor 61 that is a driving source for moving the reference plate 15 is used. That is, the amount of movement of the reference plate 15 in the width direction by the screw shaft 161 is determined according to the driving time (rotation angle) of the first motor 61 detected by the encoder 96. In the first embodiment, the encoder 96 installed in the first motor 61 is used as the movement amount detection means. However, a rotary encoder is installed on the screw shaft 161 that moves the reference plate 15 directly. This rotary encoder can also be used as a movement amount detection means.

The amount of movement in the width direction of the reference plate 15 detected by the movement amount detection means (encoder 96) and the boundary between the white portion 15a (light reflecting portion) and the black portion 15b (low light reflecting portion) detected by the CIS 36. The distance M in the width direction (and the accumulated positional deviation detection error) is obtained from the difference between the movement amount of the part and the amount of movement.
Referring to FIG. 17, when the reference plate 15 is moved from one end in the width direction of CIS 36 to the other end in the width direction by the moving mechanism, the output level of CIS 36 is shown in FIGS. 17 (A) to 17 (B). Changes so as to move together with the reference plate 15. As shown in FIG. 18, the reference plate 15 (white portion 15a and the white portion 15a) obtained from the movement amount of the reference plate 15 detected by the movement amount detecting means (encoder 96) and the change in the output level of the CIS 36 shown in FIG. The accumulated detection error at the boundary between adjacent sensor IC chips 36c1 is obtained from the amount of movement (position) of the boundary with the black portion 15b. That is, as shown in FIG. 19, as the sensor IC chip 36c1 is farther from the end portion, the interval M at the accumulated boundary portion is increased, and the accumulated detection error corresponding to the detected result is detected. Will be corrected.

As described above, when the recording medium P is not transported to the position facing the CIS 36 (contact image sensor), the transport device 30 according to the first embodiment has the white portion 15a (light reflecting portion) and the black portion. The reference plate 15 formed with 15b (low light reflecting portion) is moved to a position facing the CIS 36 by a moving mechanism to detect data used for shading correction, and adjacent sensor IC chip 36c1 (light receiving element) The distance M in the width direction between the light receiving element 36c10 and the light receiving element 36c10 adjacent to each other is detected at the boundary between the group). Then, when the recording medium P is transported to a position facing the CIS 36 and the positional deviation amount in the width direction is detected, the width-direction interval M detected by the CIS 36 is detected with respect to the detected positional deviation amount. The length is corrected.
Thereby, it is possible to detect the positional deviation amount in the width direction of the recording medium P conveyed in the predetermined conveyance direction with high accuracy.

<Embodiment 2>
A second embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 20 is a schematic configuration diagram illustrating a moving mechanism of the reference plate 15 in the transport device 30 according to the second embodiment. FIG. 21 is a schematic view showing a state in which the reference plate 15 is moved to a position facing the CIS 36 by the moving mechanism. FIG. 22 is a graph showing changes in the output of the CIS 36 when the reference plate 15 is moved.
The transport apparatus according to the second embodiment is different from that of the first embodiment in the configuration of the reference plate 15 and the configuration of the moving mechanism that moves the reference plate 15.

As shown in FIGS. 20 to 22, in the second embodiment, the reference plate 15 has a length in the width direction equal to or greater than the length in the width direction of the CIS 36 (contact image sensor). It is formed to become. The reference plate 15 has a plurality of black portions 15b (low light reflecting portions) at regular intervals with a predetermined distance in the width direction in a partial range of the white portion 15a (light reflecting portion) in the transport direction. It is formed in a scale.
Then, the moving mechanism starts moving the reference plate 15 from the retracted position (the position shown in FIG. 20) away from the CIS 36 in the transport direction, and from the one end side in the transport direction of the CIS 36 to the other end side in the transport direction. And move so that the facing position changes (from right to left in FIGS. 20 and 21).

Then, a predetermined distance (distance between black portions) of the plurality of black portions 15b recognized in advance and a distance in the width direction of the plurality of black portions 15b detected by the CIS 36 (a distance detected from the CIS output waveform in FIG. 22). ), The distance M in the width direction between the light receiving elements 36c10 at the boundary described above with reference to FIG. 13 is obtained.
Specifically, when the reference plate 15 moves to the left from the retracted position shown in FIG. 20, the CIS output as shown by the one-dot chain line in FIG. 22 faces the white portion 15a over the entire area in FIG. The CIS output is changed to a CIS output as indicated by a broken line, and is further changed to a CIS output as indicated by a solid line in FIG. Change. Then, the distance M between the light receiving elements 36c10 at the boundary portion is obtained by comparing the distance between the black portion 15b and the black portion 15b obtained by the CIS output with the known inter-black portion distance.
Then, by using the distance M in the width direction between the light receiving elements 36c10 at the obtained boundary as a correction value, the amount of misalignment of the lateral registration of the recording medium P detected by the CIS 36 in the subsequent sheet passing operation is corrected. Based on the corrected detection result, the clamping roller 31 is shifted.

Here, the moving mechanism in the second embodiment includes a one-way clutch 166, a crank disk 167 (rotating member), a tension spring 168, and the like.
The one-way clutch 166 meshes with a gear 67 that is rotationally driven by the first motor 61 of the pinching roller 31. The crank disk 167 includes a pair of disk-like members 167a and 167b and a rotating shaft 167c that holds these members at both ends. One disk-like member 167a is connected to the one-way clutch 166 so that drive transmission is possible. Further, the reference plate 15 is connected to the pair of disk-like members 167a and 167b via the connecting member 26, respectively. One end of the connecting member 26 is connected to a position away from the rotation center of the crank disk 167. As a result, when the crank disk 167 rotates, the reference plate 15 reciprocates in the transport direction. Further, a tension spring 168 is connected to the other end of the connecting member 26, and the reference plate 15 is urged to the right in FIG. 20 by the tension spring 168.

Then, in the moving mechanism configured as described above, when the first motor 61 of the pinching roller 31 rotates in the direction opposite to the rotation direction when the recording medium P is conveyed, as shown in FIG. 61 is transmitted to the crank disk 167 via the one-way clutch 166, and the crank disk 167 rotates. As a result, the reference plate 15 moves from the retracted position shown in FIG. 20 toward the left as shown in FIG. Then, the reference plate 15 is detected by the CIS 36, and detection related to shading correction and interval detection are performed.
When the reverse rotation of the first motor 61 is further performed and the crank disk 167 is rotated beyond a predetermined angle, the reference plate 15 is pushed rightward in the drawing by the connecting member 26 and is again shown in FIG. It will be returned to the retracted position shown.

As described above, the conveyance device 30 in the second embodiment also has the same structure as that in the first embodiment when the recording medium P is not conveyed to a position facing the CIS 36 (contact image sensor). The reference plate 15 on which the white portion 15a (light reflecting portion) and the black portion 15b (low light reflecting portion) are formed is moved to a position facing the CIS 36 by a moving mechanism to detect data used for shading correction. The width M between the adjacent light receiving elements 36c10 and 36c10 is detected at the boundary between adjacent sensor IC chips 36c1 (light receiving element groups). Then, when the recording medium P is transported to a position facing the CIS 36 and the positional deviation amount in the width direction is detected, the width-direction interval M detected by the CIS 36 is detected with respect to the detected positional deviation amount. The length is corrected.
Thereby, it is possible to detect the positional deviation amount in the width direction of the recording medium P conveyed in the predetermined conveyance direction with high accuracy.

<Embodiment 3>
A third embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 23 is a schematic configuration diagram illustrating a moving mechanism of the reference plate 15 in the transport device 30 according to the third embodiment. FIG. 24 is a schematic view showing a state in which the reference plate 15 has been moved to a position facing the CIS 36 by the moving mechanism. FIG. 25 is a graph showing changes in the output of the CIS 36 when the reference plate 15 is moved.
The transport apparatus in the third embodiment is different from that in the second embodiment in the configuration of the reference plate 15 and the configuration of the moving mechanism that moves the reference plate 15.

As shown in FIGS. 23 to 25, also in the third embodiment, the width in the width direction of the reference plate 15 is CIS 36 (contact image sensor) as in the second embodiment. It is formed so as to be equal to or greater than the length in the width direction. The reference plate 15 according to the third embodiment is formed such that the white portion 15a (light reflecting portion) and the black portion 15b (low light reflecting portion) are adjacent to each other at a predetermined inclination angle θ with respect to the width direction. Yes.
Then, the moving mechanism starts the movement of the reference plate 15 from the retracted position (the position shown in FIG. 23) away from the CIS 36 in the conveyance direction, and the movement amount detection means moves the reference plate 15 in the conveyance direction. While detecting the amount of movement, the CIS 36 is moved so that the facing position changes from one end side in the transport direction to the other end side in the transport direction (movement from the right to the left in FIGS. 23 and 24).

Then, the position of the boundary between the white portion 15a and the black portion 15b obtained from the movement amount of the reference plate 15 detected by the movement amount detecting unit in the carrying direction and the inclination angle θ of the black portion 15b recognized in advance, and the CIS 36 Based on the difference between the detected position of the boundary between the white portion 15a and the black portion 15b, the interval M in the width direction between the light receiving elements 36c10 at the boundary described above with reference to FIG. 13 is obtained.
Specifically, when the reference plate 15 moves to the left from the retracted position shown in FIG. 23, the rising portion of the CIS output becomes a white arrow as shown in FIG. Change direction. Then, from the interval between the light receiving elements 36c10 detected by the CIS output, an interval M in the width direction between the light receiving elements 36c10 at the boundary portion and an accumulated positional deviation detection error are obtained.
Then, using these obtained values as correction values, the lateral registration displacement amount of the recording medium P detected by the CIS 36 in the subsequent sheet passing operation is corrected, and the nipping roller 31 is based on the corrected detection result. Will be shifted.

Here, the moving mechanism 23 according to the third embodiment is configured to obtain a driving force from the third driving unit that moves the holding frame 72 in the width direction of the recording medium P.
Specifically, the moving mechanism 23 is a link mechanism that transmits driving force from the third motor 62 of the third driving means to the reference plate 15. The link mechanism is provided with a first link member 28 provided on the second cam 74 side of the third driving means and a second link member 29 provided on the reference plate 15 side. The first link member 28 is a rod-shaped member that extends in the radial direction from the rotation support shaft 74 a of the second cam 74, and is formed to rotate integrally with the second cam 74. On the other hand, the second link member 29 is a rod-like member connected to the reference plate 15 via the connecting member 26. The width direction center part of the base part 26a of the connection member 26 is connected to the one end part of the 2nd link member 29, and it is formed so that it may extend toward the conveyance direction downstream from the connection part. Further, a projecting engagement portion 29 a that can come into contact with the distal end portion of the first link member 28 is provided at the distal end portion (the distal end portion on the left side of the drawing) of the second link member 29.

When the third motor 62 is driven by the moving mechanism configured as described above and the second cam 74 is rotated clockwise as shown in FIG. 24 from the state shown in FIG. The first link member 28 also rotates in the same direction. Then, the front end portion of the first link member 28 comes into contact with the engaging portion 29 a of the second link member 29, and the second link member 29 resists the urging force of the tension spring 24 by the first link member 28. Is pushed to the left. As a result, the reference plate 15 moves to a position facing the CIS 36.
Further, when the third motor 62 is rotated in the reverse direction from the state shown in FIG. 23, the second cam 74 is rotated in the opposite direction (counterclockwise) to the direction described above, and the first link is moved in the same direction. The member 28 also rotates. As a result, as shown in FIG. 14A, the reference plate 15 is moved to the right in the drawing by the urging force of the tension spring 24 and returned to the retracted position shown in FIG.
In the third embodiment, as a movement amount detecting means for detecting the movement amount of the reference plate 15, an encoder sensor 78 (FIG. 4) for detecting an encoder wheel 77 installed on the rotation support shaft 74a of the second cam 74. Can be referred to).

As described above, the transport device 30 according to the third embodiment is similar to the above-described embodiments when the recording medium P is not transported to a position facing the CIS 36 (contact image sensor). The reference plate 15 on which the white portion 15a (light reflecting portion) and the black portion 15b (low light reflecting portion) are formed is moved to a position facing the CIS 36 by a moving mechanism to detect data used for shading correction. The width M between the adjacent light receiving elements 36c10 and 36c10 is detected at the boundary between adjacent sensor IC chips 36c1 (light receiving element groups). Then, when the recording medium P is transported to a position facing the CIS 36 and the positional deviation amount in the width direction is detected, the width-direction interval M detected by the CIS 36 is detected with respect to the detected positional deviation amount. The length is corrected.
Thereby, it is possible to detect the positional deviation amount in the width direction of the recording medium P conveyed in the predetermined conveyance direction with high accuracy.

In each of the above embodiments, the present invention is applied to the conveying device 30 in which the sandwiching roller 31 that functions as a horizontal registration / skew correction roller also functions as a registration roller. However, the present invention can be applied. The conveying device is not limited to this, and even a conveying device having other configurations is applicable to all conveying devices as long as the conveying device performs skew feeding correction and lateral registration correction. The present invention can be applied to. For example, the present invention can naturally be applied to a conveyance device in which a registration roller is installed on the downstream side of the sandwiching roller 31 that functions as a horizontal registration / skew correction roller.
In each of the above embodiments, the present invention is applied to the conveyance device 30 that performs skew correction and lateral registration correction of a transfer sheet as a recording medium P on which an image is formed. Naturally, the present invention can also be applied to a transport apparatus that performs the skew correction and the lateral registration correction.
Further, in each of the above embodiments, the present invention is applied to the conveyance device 30 installed in the monochrome image forming apparatus 1, but the present invention is naturally also applied to the conveyance device installed in the color image forming apparatus. The invention can be applied.
In each of the above embodiments, the present invention is applied to the conveyance device 30 installed in the electrophotographic image forming apparatus 1. However, the application of the present invention is not limited to this, and other methods. Even if it is a transport apparatus installed in the image forming apparatus (for example, an inkjet image forming apparatus or an offset printing machine), if it is a transport apparatus that performs skew correction and lateral registration correction, Of course, the present invention can also be applied to all of these transport apparatuses.
Even in those cases, the same effects as those of the above-described embodiments can be obtained.

Further, in each of the above embodiments, the first driving means is configured to push the holding frame 72 (projection 72a) indirectly via the lever member 81 by the first cam 84. The first driving means can also be configured to push the holding frame directly.
In each of the above embodiments, the second drive means is configured to push the holding frame 72 (support shaft 73) directly by the second cam 74, but the holding frame is indirectly set by the second cam. The second drive means can also be configured to push.
In each of the above embodiments, the cam mechanisms are used as the second and third driving means, respectively. However, the second and third driving means are not limited to these, and for example, the second and third driving means. For example, a solenoid mechanism or a pinion / rack mechanism may be used.
Even in those cases, the same effects as those of the above-described embodiments can be obtained.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1 image forming apparatus (image forming apparatus main body),
15 reference plate,
15a White part (light reflection part),
15b Black part (low light reflection part),
16 Contact glass,
17 Straight conveyance guide plate (guide plate),
30 transport device,
31 Nipping roller (horizontal registration / skew correction roller, registration roller),
31a driven roller,
31b Driving roller,
35 Skew detection sensor (skew detection means),
36 CIS (Contact Image Sensor),
36a light source,
36b lens,
36c light receiving part,
36c1 sensor IC chip (light receiving element group),
36c10 light receiving element (pixel),
37 second skew detection sensor (auxiliary detection means),
51 alignment section,
61 1st motor (1st drive means),
62 third motor (third driving means),
63 second motor (second driving means),
65 2-stage spline coupling,
70 body frame (device frame),
71 Base frame (device frame),
71a guide part (hole part),
72 holding frame (holding member),
73 spindle,
74 second cam (third drive means),
84 first cam (second driving means),
95 Free bearing (relay support member),
96 Encoder (movement amount detection means),
P Recording medium (sheet).

JP 2010-24059 A

Claims (9)

A transport device for transporting a recording medium,
A contact image sensor that is disposed so as to extend in the width direction and detects a positional deviation amount in the width direction of the recording medium conveyed in the conveyance direction substantially orthogonal to the width direction;
A reference plate in which a light reflecting portion that reflects light and a low light reflecting portion that is formed so that a reflectance of light is smaller than that of the light reflecting portion;
A moving mechanism for moving the reference plate from a retracted position not facing the contact image sensor to a facing position facing the contact image sensor, or from the facing position to the retracted position;
With
The contact image sensor is
A light source;
A lens,
A light receiving element group in which a plurality of light receiving elements formed so as to be able to receive light emitted from the light source and reflected by the recording medium facing the contact image sensor or the reference plate is arranged in the width direction has a width. A plurality of light receiving units arranged in parallel in the direction;
Comprising
When the recording medium is not transported to a position facing the contact image sensor, the contact image sensor moves the reference plate from the retracted position to the facing position by the moving mechanism at a predetermined timing. Detecting data used in the shading correction of, and detecting the interval in the width direction between the light receiving element and the light receiving element adjacent to each other at the boundary between the adjacent light receiving element groups,
When the recording medium is conveyed to a position facing the contact image sensor and the positional deviation amount in the width direction of the recording medium is detected, the contact image image is detected with respect to the detected positional deviation amount. A conveyance device that corrects the length of the interval in the width direction detected by a sensor. When detecting data to be used in the shading correction, the contact image sensor detects the interval in the width direction, and accumulates the position by the position in the width direction for each light receiving element in the contact image sensor. Detect misalignment detection error,
When the recording medium is conveyed to a position facing the contact image sensor and the positional deviation amount in the width direction of the recording medium is detected, the contact image image is detected with respect to the detected positional deviation amount. The transport apparatus according to claim 1, wherein a length of the interval in the width direction detected by a sensor and the accumulated positional deviation detection error are corrected. The reference plate is
The length in the width direction is formed to be shorter than the length in the width direction of the contact image sensor,
The light reflecting portion and the low light reflecting portion are formed so as to be adjacent in the width direction,
The moving mechanism starts the movement of the reference plate from the retracted position separated in the width direction with respect to the contact image sensor, and detects a movement amount of the reference plate in the width direction by a movement amount detection unit. While moving so that the facing position changes from one end side in the width direction of the contact image sensor toward the other end side in the width direction,
A movement amount in the width direction of the reference plate detected by the movement amount detection means, and a movement amount of a boundary portion between the light reflection portion and the low light reflection portion detected by the contact image sensor. The conveyance device according to claim 1, wherein the interval in the width direction is obtained from the difference. The reference plate is
The length in the width direction is equal to or greater than the length in the width direction of the contact image sensor,
A plurality of the low light reflecting portions are formed in a scale shape with a predetermined distance in the width direction in a partial range in the transport direction in the light reflecting portion,
The moving mechanism starts to move the reference plate from the retracted position away from the contact image sensor in the transport direction, from one end side in the transport direction of the contact image sensor to the other end side in the transport direction. Move so that the facing position changes toward
The distance in the width direction is determined based on the difference between the predetermined distance between the plurality of low light reflection portions recognized in advance and the distance in the width direction of the plurality of low light reflection portions detected by the contact image sensor. The conveyance device according to claim 1 or 2, wherein The reference plate is
The length in the width direction is equal to or greater than the length in the width direction of the contact image sensor,
The light reflecting portion and the low light reflecting portion are formed adjacent to each other at a predetermined inclination angle with respect to the width direction,
The moving mechanism starts the movement of the reference plate from the retracted position away from the contact image sensor in the conveyance direction, and detects the movement amount of the reference plate in the conveyance direction by a movement amount detection unit. While moving so that the facing position changes from one end side in the transport direction of the contact image sensor toward the other end side in the transport direction,
The position of the boundary between the light reflecting portion and the low light reflecting portion determined from the amount of movement of the reference plate in the carrying direction detected by the amount of movement detecting means and the inclination angle recognized in advance; and the contact The distance in the width direction is obtained from a difference between a position of a boundary portion between the light reflecting portion and the low light reflecting portion detected by an image sensor. The conveying apparatus as described. Skew detection means for detecting the amount of positional deviation in the oblique direction of the recording medium conveyed in the conveyance direction;
A nipping roller that is rotationally driven by the first driving means and conveys the recording medium in a nipped state;
A holding member that rotatably holds the clamping roller;
A relay support member that is installed in a frame of the apparatus and supports the holding member so as to be movable in either a width direction or an oblique direction with respect to the frame;
With
The holding member comprises a support shaft that fits into a guide portion formed to extend in the width direction in the frame;
The holding roller is installed on the frame and is configured to rotate the holding roller together with the holding member in an oblique direction by rotating the holding member about the support shaft based on a detection result of the skew detection means. Second driving means,
Installed on the frame, the holding roller and the holding roller can be moved in the width direction by moving the support shaft along the guide portion based on the detection result of the contact image sensor. Third driving means;
The transport apparatus according to claim 1, further comprising: The skew detection means and the contact image sensor are respectively arranged on the upstream side in the transport direction with respect to the sandwiching roller,
The sandwiching roller is rotated from a reference position before sandwiching the recording medium so as to correct the displacement amount of the recording medium in the oblique direction based on the detection result of the skew detection means, and sandwiches the recording medium. The reference position before the recording medium is sandwiched so as to return to the reference position and to correct the positional deviation in the width direction of the recording medium based on the detection result of the contact image sensor. The transport apparatus according to claim 6, wherein the transport apparatus moves in the width direction so as to return to the reference position after the recording medium is sandwiched by moving in the width direction from the position.   The positional deviation amount in the width direction and / or the oblique direction of the recording medium after the positional deviation amount in the width direction and the oblique direction is corrected by the sandwiching roller is detected by the auxiliary detection means, and the recording is performed based on the detection result. The transport apparatus according to claim 7, wherein the positional deviation amount in the width direction and / or the oblique direction of the medium is further corrected.   An image forming apparatus comprising the transport device according to claim 1.

Images