JP2021134035A - Sheet guide, sheet carrier, image reader and image forming apparatus - Google Patents

Abstract

To provide a sheet guide capable of suppressing the variation of a sheet path or the like as compared to the conventional.SOLUTION: A sheet guide 50 comprises a first guide member 85 and a second guide member 85d sandwiching a first transport path 54a for a sheet, in which at least the first guide member 85 can be changed in position. The first guide member 85 and the second guide member 85d are configured in one body so as to be changed in position. By providing a third guide member 90 sandwiching a second transport path 51a together with an opposite face 85b of the first guide member 85 to the second guide member 85d, a transport path for sheet acceptance may be changeable over between the first transport path 54a and the second transport path 51a through a position change of the first guide member 85 and second guide member 85d.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sheet guide device, a sheet transfer device, an image reading device, and an image forming device.

Conventionally, there is known a seat guide device that includes a first guide member and a second guide member that sandwich a first transfer path of a sheet and can change the posture of at least the first guide member.
For example, Patent Document 1 describes an image forming device that receives a sheet sent from a fixing device in a first transport path leading to a reversing mechanism for retransmitting the sheet to an image forming unit by changing the posture of the first guide member. There is. This image forming apparatus also includes an image reading apparatus provided with an image reading unit for reading an image of a sheet sent from the fixing apparatus.

However, it is desired to suppress variations in the trajectory and moving speed of the seat guided by the seat guide device.

In order to solve the above-mentioned problems, the present invention includes a first guide member and a second guide member that sandwich the first transfer path of the seat, and at least in a seat guide device capable of changing the posture of the first guide member. The first guide member and the second guide member can be integrated to change the posture.

According to the present invention, variations in the trajectory of the sheet and the like can be suppressed as compared with the conventional case.

The peripheral schematic block diagram of the transfer switching apparatus of the image forming apparatus which concerns on embodiment. The schematic block diagram of the image forming apparatus. Explanatory drawing of sheet transport in a comparative example. Explanatory drawing of sheet transport in a comparative example. Explanatory drawing of sheet transport in a comparative example. Explanatory drawing of sheet transfer in embodiment. Explanatory drawing of sheet transfer in this embodiment. Explanatory drawing of sheet transfer in this embodiment. The explanatory view of the specific example of the transport path switching member of this embodiment. Explanatory drawing of the transport path switching member which concerns on a modification.

Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus for forming an image by an electrophotographic method will be described. First, the basic configuration of the image forming apparatus according to the embodiment will be described.
FIG. 2 is a schematic configuration diagram showing an example of the image forming apparatus 100 according to the embodiment.
The image forming apparatus 100 includes two optical writing units 1a and 1b and four process units 2Y for forming a toner image of yellow (Y), magenta (M), cyan (C), and black (K). , 2M, 2C, 2K. Further, the paper feed path 30, the pre-transfer transfer path 31, the manual feed path 32, the manual feed tray 33, the resist roller pair 34, the transfer belt unit 35, the fixing device 40, the transfer path switching device 50, the paper discharge path 51, and the paper discharge. It also includes a roller pair 52, a paper ejection tray 53, a paper feeding device 7, a retransmission device, and the like.

The paper feed device 7 serving as a feeding means includes a first paper feed cassette 101 and a second paper feed cassette 102 as loading units. The first paper cassette 101 and the second paper cassette 102 each house a bundle of sheets P as a recording material inside. Then, by rotating the paper feed rollers 101a and 102a, the top sheet P in the paper bundle is sent out toward the paper feed path 30. The paper feed path 30 is followed by a pre-transfer transfer path 31 for transporting the sheet immediately before the secondary transfer nip, which will be described later. The sheet P sent out from the first paper cassette 101 or the second paper cassette 102 enters the pre-transfer transfer path 31 via the paper feed path 30. The sheet includes paper, coated paper, label paper, OHP sheet, film and the like.

A manual feed tray 33 is arranged on the side surface of the device housing so as to be openable and closable with respect to the housing, and a bundle of paper is manually fed to the upper surface of the tray in a state of being open with respect to the housing. The top sheet P in the manually fed paper bundle is fed toward the pre-transfer transfer path 31 by the delivery roller of the manual feed tray 33.

The two optical writing units 1a and 1b each have a laser diode, a polygon mirror, various lenses, and the like. Then, based on the image information read by the scanner outside the device and the image information sent from the personal computer, the laser diode is driven to drive the photoconductors 3Y, 3M, 3C of the process units 2Y, 2M, 2C, 2K. , 3K is light-scanned. Specifically, the photoconductors 3Y, 3M, 3C, and 3K of the process units 2Y, 2M, 2C, and 2K are rotationally driven in the counterclockwise direction in the drawing by the driving means. The optical writing unit 1YM performs an optical scanning process by irradiating the driven photoconductors 3Y and 3M with laser light while deflecting them in the direction of the rotation axis. As a result, electrostatic latent images based on the Y image information and the M image information are formed on the photoconductors 3Y and 3M, respectively. Further, the optical writing unit 1CK performs an optical scanning process by irradiating the driven photoconductors 3C and 3K with laser light while deflecting them in the direction of the rotation axis. As a result, electrostatic latent images based on the C image information and the K image information are formed on the photoconductors 3C and 3K, respectively.

The process units 2Y, 2M, 2C, and 2K each have drum-shaped photoconductors 3Y, 3M, 3C, and 3K as latent image carriers. Further, each of the process units 2Y, 2M, 2C, and 2K supports various devices arranged around the photoconductors 3Y, 3M, 3C, and 3K as one unit on a common support. It is removable from the image forming unit body. The process units 2Y, 2M, 2C, and 2K have the same configuration except that the colors of the toners used are different from each other. Taking the process unit 2Y for Y as an example, it has a photoconductor 3Y and a developing device 4Y for developing an electrostatic latent image formed on the surface of the photoconductor 3Y into a Y toner image. Further, the transfer adhering to the surface of the photoconductor 3Y after passing through the charging device 5Y that uniformly charges the surface of the photoconductor 3Y that is driven to rotate and the primary transfer nip for Y described later. It also has a drum cleaning device 6Y for cleaning residual toner.

The illustrated image forming apparatus 100 has a so-called tandem type configuration in which four process units 2Y, 2M, 2C, and 2K are arranged along the endless movement direction with respect to the intermediate transfer belt 61 described later.

As the photoconductor 3Y, a drum-shaped one in which a photosensitive layer is formed by applying a photosensitive organic photosensitive material to a raw tube such as aluminum is used. However, an endless belt-shaped one may be used.

The developing apparatus 4Y develops a latent image using a two-component developer (hereinafter, simply referred to as “developer”) containing a magnetic carrier and a non-magnetic Y toner. As the developing apparatus 4Y, a type that develops with a one-component developer that does not contain a magnetic carrier may be used instead of the two-component developer. To the developing device 4Y, the Y toner in the Y toner bottle 103Y is appropriately replenished by the Y toner replenishing device.

As the drum cleaning device 6Y, a method in which a cleaning blade made of polyurethane rubber, which is a cleaning member, is pressed against the photoconductor 3Y is used, but other methods may be used. For the purpose of improving the cleanability, the image forming apparatus 100 employs a method in which a rotatable fur brush is brought into contact with the photoconductor 3Y. This fur brush also has a role of applying the lubricant to the surface of the photoconductor 3Y while scraping the lubricant from the solid lubricant to make a fine powder.

A static elimination lamp is arranged above the photoconductor 3Y, and this static elimination lamp is also a part of the process unit 2Y. The static elimination lamp removes static electricity from the surface of the photoconductor 3Y after passing through the drum cleaning device 6Y by irradiating light. The surface of the statically eliminated photoconductor 3Y is uniformly charged by the charging device 5Y, and then subjected to optical scanning by the above-mentioned optical writing unit 1YM. The charging device 5Y is driven to rotate while receiving a charging bias from a power source. Instead of such a method, a scorotron charger method in which the photoconductor 3Y is charged in a non-contact manner may be adopted.

Although the process unit 2Y for Y has been described above, the process units 2M, 2C, and 2K for M, C, and K also have the same configuration as that for Y.

A transfer unit 60 is arranged below the four process units 2Y, 2M, 2C, and 2K. The transfer unit 60 drives the rotation of any one of the support rollers while bringing the intermediate transfer belt 61, which is an endless belt stretched by a plurality of support rollers, into contact with the photoconductors 3Y, 3M, 3C, and 3K. In the figure, it runs clockwise (endless movement). As a result, primary transfer nip for Y, M, C, K in which the photoconductors 3Y, 3M, 3C, 3K and the intermediate transfer belt 61 come into contact with each other is formed.

In the vicinity of the primary transfer nips for Y, M, C, and K, the primary transfer roller 62Y, as a primary transfer member disposed in a space surrounded by the inner peripheral surface of the intermediate transfer belt, that is, in the belt loop. The intermediate transfer belt 61 is pressed toward the photoconductors 3Y, 3M, 3C, and 3K by 62M, 62C, and 62K. A primary transfer bias is applied to each of these primary transfer rollers 62Y, 62M, 62C, and 62K by a power source. As a result, a primary transfer electric field is formed in the primary transfer nips for Y, M, C, and K to electrostatically move the toner image on the photoconductors 3Y, 3M, 3C, and 3K toward the intermediate transfer belt 61. Will be done.

On the outer peripheral surface of the intermediate transfer belt 61 that sequentially passes through the primary transfer nip for Y, M, C, and K with the endless movement in the clockwise direction in the figure, toner images are sequentially formed by each primary transfer nip. It is superposed and first-order transferred. By the primary transfer of this superposition, a four-color superposition toner image (hereinafter referred to as "four-color toner image") is formed on the outer peripheral surface of the intermediate transfer belt 61.

A secondary transfer roller 72 as a secondary transfer member is arranged below the intermediate transfer belt 61 in the drawing. The secondary transfer roller 72 abuts on the intermediate transfer belt 61 from the outer peripheral surface of the belt to the hanging portion of the intermediate transfer belt 61 with respect to the secondary transfer backup roller 68 to form a secondary transfer nip. As a result, a secondary transfer nip is formed in which the outer peripheral surface of the intermediate transfer belt 61 and the secondary transfer roller 72 come into contact with each other.

A secondary transfer bias is applied to the secondary transfer roller 72 by a power source. On the other hand, the secondary transfer backup roller 68 in the belt loop is grounded. As a result, a secondary transfer electric field is formed in the secondary transfer nip.

The resist roller pair 34 described above is arranged on the right side in the drawing of the secondary transfer nip, and the sheet P sandwiched between the rollers is arranged at a timing that can be synchronized with the four-color toner image on the intermediate transfer belt 61. Send to the next transfer nip. In the secondary transfer nip, the four-color toner image on the intermediate transfer belt 61 is collectively secondary-transferred to the sheet P due to the influence of the secondary transfer electric field and the nip pressure, and is combined with the white color of the sheet P to form a full-color image.

The transfer residual toner that has not been transferred to the sheet P by the secondary transfer nip adheres to the outer peripheral surface of the intermediate transfer belt 61 that has passed through the secondary transfer nip. The transfer residual toner is cleaned by the belt cleaning device 75 that comes into contact with the intermediate transfer belt 61.

The sheet P that has passed through the secondary transfer nip is separated from the intermediate transfer belt 61 and delivered to the transfer belt unit 35. The transport belt unit 35 is endlessly moved in the counterclockwise direction in the drawing by the rotational drive of the drive roller 37 while the endless belt-shaped transport belt 36 is stretched by the drive roller 37 and the driven roller 38. Then, while holding the sheet P delivered from the secondary transfer nip on the tensioning surface on the outer peripheral surface of the transport belt, the sheet P is transported along with the endless movement of the transport belt 36 and delivered to the fixing device 40 as the fixing means.

In the image forming apparatus 100, the reverse transfer means is configured by the transfer path switching device 50, the retransmission path 54, the switchback path 55, the transfer path 56 after switchback, and the like. Specifically, the transport path switching device 50 switches the subsequent transport destination of the sheet P received from the fixing device 40 between the paper discharge path 51 and the retransmission path 54. When executing a print job in the single-sided mode in which an image is formed only on the first surface of the sheet P, the transfer destination of the sheet P is set to the output path 51. As a result, the sheet P on which the image is formed only on the first surface is sent to the paper ejection roller pair 52 via the paper ejection path 51, and is ejected onto the paper ejection tray 53 outside the machine. Further, when executing a print job in the double-sided mode in which images are formed on both sides of the sheet P, when the sheet P having the images fixed on both sides is received from the fixing device 40, the destination of the sheet P is also transferred. Is set to the output path 51. As a result, the sheet P on which the images are formed on both sides is ejected onto the output tray 53 outside the machine. On the other hand, when the sheet P in which the image is fixed only on the first surface is received from the fixing device 40 at the time of executing the print job in the double-sided mode, the transport destination of the sheet P is set to the retransmission path 54.

A switchback path 55 is connected to the retransmission path 54, and the sheet P sent to the retransmission path 54 enters the switchback path 55. Then, when the entire region of the seat P in the transport direction enters the switchback path 55, the transport direction of the seat P is reversed and the seat P switches back. In addition to the retransmission path 54, the switchback path 55 is connected to the transfer path 56 after switchback, and the switchback seat P enters the transfer path 56 after switchback. At this time, the sheet P is turned upside down. Then, the sheet P that has been turned upside down is retransmitted to the secondary transfer nip via the transport path 56 and the paper feed path 30 after switchback. The sheet P on which the toner image is also transferred to the second surface by the secondary transfer nip is transferred to the transfer path switching device 50 and the paper ejection path 51 after the toner image is fixed to the second surface via the fixing device 40. Paper is ejected onto the output tray 53 via the output roller pair 52.

In the image forming apparatus 100, a purge tray 58 for discharging unnecessary paper is provided at the lower part on the left side in the drawing of the apparatus. For example, when the device is stopped due to jam or the like, the sheet existing in the device is conveyed to the purge tray 58. Specifically, a tray transport path 57 for transporting the sheet to the purge tray 58 is connected to the retransmission path 54, and when transporting the sheet to the purge tray 58, the transport destination of the sheet P is set to the tray transport path 57. .. As a result, the sheet conveyed to the retransmission path 54 is conveyed to the tray transfer path 57 before the transfer path 56 after switchback, and is discharged to the purge tray 58.

FIG. 1 is a schematic peripheral configuration diagram of a transport path switching device 50 as a seat guide device in the image forming device 100. In the image forming apparatus 100 of FIG. 2, the sheet P on which the image is fixed by the fixing device 40 passes through the paper cooling device 84 shown in FIG. After that, it is conveyed to the upstream transfer roller 81 as the upstream sheet transfer means arranged on the downstream side of the paper cooling device 84, and the transferred image on the sheet P is read when passing through the image reading unit 80. The installation location of the image reading unit 80 corresponds to the scanning location. A guide plate 87 as an upstream guide member is provided between the upstream side transport roller 81 and the image reading unit 80, and the transport path 87a sandwiched between them corresponds to the third transport path.

The read data of this transferred image can be used for various purposes depending on what kind of image the transferred image to be read is. When the transferred image to be read is, for example, a user's output image, it can be compared with the image data for image formation corresponding to the output image as in Patent Document 1, or the output image which seems to be good as in Patent Document 2 is read. It can be used for quality determination (determination of the presence or absence of defects) of the output image, such as comparison with the comparison data stored in. Further, when the transferred image to be read is a detection image for preventing image formation position deviation and magnification deviation on the front and back sides in double-sided printing described in Patent Document 3, it can be used to control such deviation correction. .. Further, when the transferred image to be read is a well-known image of a measurement pattern for preventing color shift and skew, it can be used for writing correction control for preventing color shift and skew. These are just examples, and the transferred image can be read according to other uses. Hereinafter, the defect detection of the transferred image will be described as an example.

The image reading unit 80 is arranged upstream of the transport path switching device 50. The transport path switching device 50 includes a transport path switching member 85 as a first guide member. Each of the transport path switching members 85 includes a lower surface 85a and an upper surface 85b that serve as guide surfaces, and the posture can be changed by rotating while being supported by the rotation shaft 85c. It functions as a so-called gate member or a switching claw member for a transport path. A lower guide plate 85d as a second guide member facing the lower surface 85a at intervals is attached to the transport path switching member 85, and the posture can be changed integrally. A specific example of the transport path switching member 85 will be described later with reference to FIG. The space sandwiched between the lower surface 85a of the transport path switching member 85 and the lower guide plate 85d is a transport path 54a for receiving the sheets from the fixing device 40 and the paper cooling device 84 and guiding them to the retransmission path 54. This transport path 54a corresponds to the first transport path.

The transfer path switching device 50, together with the upper surface 85b of the transfer path switching member 85, constitutes a transfer path 51a as a second transfer path for receiving the sheets from the fixing device 40 and the paper cooling device 84 and guiding them to the paper discharge path 51. An upper fixed guide plate 90 as a third guide member is also provided. This transport path 51a corresponds to the second transport path. The state of FIG. 1 shows a rotational posture in which the transport path switching member 85 guides the sheet P to the paper discharge path 51. When the sheet P is conveyed to the retransmission path 54, the transfer path switching member 85 is rotated in the direction of the arrow A to switch the posture (see FIG. 8). By such a posture change, the transport path for receiving the sheet can be switched between the transport path 54a to the retransmission path 54 and the transport path 51a to the paper discharge path 51. By locating the image reading unit 80 on the upstream side of the transport path switching device 50 that switches between the paper ejection path 51 and the retransmission path 54, the image reading unit 80 is located on the first side in the single-sided print mode and on the double-sided print mode. It is possible to read the transferred image on the second surface side for detecting defects.

In the downstream transfer roller 82 in the paper ejection path 51 and the downstream transfer roller 83 in the retransmission path 54, the sheet P loosens and comes into contact with the transfer path switching member 85, and the sheet P and the image on the sheet P are scratched or streaked. In order to prevent the uneven gloss of the sheet P from occurring, the speed is set to be faster than the speed of the upstream transfer roller 81, and the slack of the sheet P is suppressed. The downstream transfer roller 83 in the retransmission path 54 corresponds to the downstream sheet transfer means.

3 and 4 are schematic configuration diagrams of the periphery of the transport path switching device 50 in the image forming apparatus 100 according to the comparative example. In this comparative example, the lower guide 86 facing the lower surface 85a of the transport path switching member 85 is fixed. 3 and 4 show a state in which the transport path switching member 85 guides the sheet P to the retransmission path 54. 3 (a), 3 (b), 4 (a), and 4 (b) show how the sheet P is being conveyed.

As shown in FIG. 3A, after the sheet P has passed through the image reading unit 80, it is conveyed between the lower surface 85a of the transfer path switching member 85 and the lower fixed guide 86. In order to secure the operating range of the transport path switching member 85, the lower fixed guide 86 has a wide transport path during this period, and the seat P may be slackened. Therefore, the speed of the downstream transfer roller 82 is set higher than the speed of the upstream transfer roller 81 to suppress the slack of the sheet P. FIG. 3B shows a state in which the sheet P is conveyed by both the upstream transfer roller 81 and the downstream transfer roller 82, and due to the speed difference between the two, the state of large slack shown by the solid line is changed to the state shown by the broken line. And reduce slack.

FIG. 4A shows a state in which the seat P has almost no slack as shown by the solid line immediately before the rear end of the seat P passes through the upstream transfer roller 81. FIG. 4B shows a state immediately after the rear end of the seat P has passed through the upstream transfer roller 81. If the state of FIG. 4A is a state in which the sheet P is in a stretched state after the slack of the sheet P is removed, the sheet P is moved to the downstream side transfer roller 82 after the rear end of the sheet P has passed through the upstream side transfer roller 81. When transported at the speed of, the tensioned state is restored due to the difference in linear speed of the transport rollers, the characteristics of the seat P, and the like.

Along with this, the sheet P loosens as shown by the solid line in FIG. 4B, and the rear end side momentarily moves to the downstream side at a relatively high speed. As a result, the transfer speed of the sheet P in the image reading unit 80 may increase. Such an increase in speed causes a difference between the scanned image and the actual image in the image reading unit 80.

Unlike the state shown in FIG. 4A, that is, the state in which the sheet P has almost no slack as shown by the solid line, immediately before the rear end of the sheet P passes through the upstream transfer roller 81, FIG. 5 (b) ), The slack of the sheet P may remain large. For example, the slack of the seat P becomes large depending on how the seat P penetrates into the downstream transfer roller 82, the characteristics of the seat P, and the like. Then, even if the downstream transfer roller 82 pulls the sheet P at a speed faster than that of the upstream transfer roller 81, the slack of the sheet P remains even just before the rear end of the sheet P passes through the upstream transfer roller.

In this case, after the rear end of the sheet P has passed through the upstream transfer roller 81, the sheet P is conveyed only by the downstream transfer roller 82 as shown in FIG. 5B, but the sheet P is conveyed. Until the slack is removed (dotted line in FIG. 3), the transport speed of the sheet P in the image reading unit 80 is reduced, and a difference between the scanned image and the actual image in the image reading unit 80 occurs. ..

FIG. 6A shows an example of a transferred image for explaining the difference between the read image and the actual image in the transport path switching device 50 of the image forming apparatus 100 according to the comparative example. For example, consider the case where a reference pattern chart having a certain interval and a reference pattern actual interval Lr with respect to the transport direction as shown in FIG. 6A is printed. The reference pattern detection interval Ll represents the chart interval when detected by the image reading unit 80. Then, a difference may occur between the reference pattern actual interval Lr and the reference pattern detection interval Ll. The dashed line on the rear end side of the sheet, that is, on the upstream side in the transport direction, shows that the reference pattern detection interval Ll is longer than the reference pattern actual interval Lr.

6 (b) and 6 (c) show the image reading results of the transport path switching device 50 of the image forming apparatus 100 according to the comparative example, respectively. This is an example of a graph showing the relationship between the chart reading position on the horizontal axis and the difference between the reference pattern actual interval Lr and the reference pattern detection interval Ll (“Ll-Lr”) on the vertical axis.

FIG. 6B shows a case where the sheet P is loosened immediately before the rear end of the sheet P passes through the upstream transfer roller 81, and the sheet P passes through the downstream transfer roller 82. After that, the transfer speed of the sheet P in the image reading unit 80 will decrease. As a result, as shown by the broken line in FIG. 6A, the reference pattern detection interval Ll becomes longer than the reference pattern actual interval Lr. Therefore, the graph of FIG. 6B tends to be convex upward.

FIG. 6C shows a case where the sheet P is in a stretched state immediately before the rear end of the sheet P passes through the upstream transfer roller 81, and the sheet P has passed through the downstream transfer roller 82. Immediately after that, the transfer speed of the sheet P in the image reading unit 80 increases, so that the detection interval becomes shorter than the actual interval, and the graph tends to be convex downward.

Conventionally, the image defect detection device has been mainly provided outside the image forming device. By providing an image reading mechanism inside the image forming apparatus, there is an advantage that cost reduction and downsizing can be performed. In this case, since it is necessary to be able to read the front surface image and the back surface image, it is desirable to arrange the image reading mechanism between the fixing portion for fixing the image on the paper and the transport path switching portion for switching the transport direction between the front surface and the back surface. .. Due to the problem of mounting space inside the image forming apparatus, the image reading mechanism may be arranged immediately before the transport path switching portion. On the other hand, the transport route switching unit generally switches the transport route by using an movable gate member. The transport path is widened to secure the operating range of the movable gate member, and the paper may be loosened in the transport path. In that case, the paper may come into contact with the gate member due to the slack, and scratches or streaky gloss unevenness may occur on the paper or the image on the paper. The speed of the transport roller on the downstream side of the switching unit may be set faster than the speed of the transport roller on the upstream side of the transport path switching unit. In this case, depending on the slack state of the paper, uneven feeding of the paper transport occurs when the rear edge of the paper passes through the upstream transport roller of the image reading unit, and as a result, the image reading accuracy in the sub-scanning direction of the image reading unit occurs. There was a problem of making it worse. In order to reduce costs and downsize, reading accuracy is particularly likely to deteriorate in a configuration in which a transport roller or the like that restrains the sheet is not arranged between the image reading mechanism and the transport path switching unit. The image forming apparatus of this embodiment solves this problem.

FIG. 7 is an explanatory diagram of sheet P transport by the transport path switching device 50 in the image forming apparatus 100 of the present embodiment. The transport path switching member 85 guides the sheet P to the retransmission path 54. In FIG. 1, in which the transport path switching member 85 guides the sheet P to the paper discharge path 51, the sheet P that has passed through the image reading unit 80 proceeds linearly as it is to the transport path 51a by the upper surface 58b or the like. In FIG. 7, which leads to the retransmission path 54, the sheet P that has passed through the image reading unit 80 has a large degree of bending of the transfer path as it advances to the transfer path 54a by the lower surface 58a or the like. That is, the radius of curvature is small. This point is the same in the comparative examples (FIGS. 3 to 5). The sheet P is more likely to be curved or slackened in the transport path having a larger degree of bending of the transport path.

FIG. 7A shows a state in which the sheet P is conveyed by both the upstream transfer roller 81 and the downstream transfer roller 82. FIG. 7B shows a state immediately after the rear end of the seat P has passed through the upstream transfer roller 81. Since the posture of the lower surface 85a of the transport path switching member 85 and the lower guide plate 85d can be changed integrally, the vertical height (gap) of the transport path between the two can be set between the lower surface 85a and the lower surface 85a in the comparative example. It can be set narrower than the distance from the side fixing guide 86. That is, a narrow gap transport path can be formed at this portion.

As a result, it is possible to suppress the size of the curved shape that deviates from the stretched state, for example, which is indicated by the broken line such as the slack state shown by the solid line in FIG. 3B regarding the comparative example, and the slack of the sheet P can be suppressed. That is, the variation in the trajectory of the seat P can be suppressed. Therefore, as shown in FIG. 7B, it is possible to suppress slackening and bending of the sheet immediately after the rear end of the sheet P has passed through the upstream transfer roller 81, and the image reading unit 80 suddenly fluctuates (moves) the transfer speed. (Variation in speed) can be suppressed. As a result, the image reading in the sub-scanning direction can be made highly accurate. That is, it is possible to suppress the occurrence of reading error due to the fluctuation of the sheet passing speed in the image reading unit.

FIG. 8 shows the image reading result in the transport path switching device 50 of the image forming apparatus 100 of the present embodiment. The chart reading position is taken on the horizontal axis, and the reference pattern actual interval Lr and the reference pattern detection interval Ll are shown. This is an example of a graph showing the relationship between the two, with the difference (“Ll-Lr”) on the vertical axis.

FIG. 8A shows a case where the seat P is loosened immediately before the rear end of the sheet P passes through the upstream transfer roller 81, and FIG. 8B shows a case where the rear end of the sheet P is the upstream transfer roller. This is the case where the seat P is in a stretched state immediately before passing through 81. In either case, it can be seen that the image reading accuracy is improved as compared with the comparative examples shown in FIGS. 6 (b) and 6 (c). The difference between the reference pattern actual interval Lr and the reference pattern detection interval Ll could be kept within the target specification range.

FIG. 9 is an explanatory diagram of a specific example of the transport path switching member 85. 9 (a) is an exploded perspective view seen from diagonally above, FIG. 9 (b) is an exploded perspective view seen from diagonally below, and FIG. 9 (c) is a front view of the assembled state. The lower guide plate 85d is fixed to the transport path switching member 85 with screws 91. In this specific example, the upstream side portion 85a1 and the downstream side portion 85a2 of the lower surface 85a of the transport path switching member 85 have the following shapes. That is, as shown by a hidden line (broken line) in FIG. 9C, the lower surface 85a is a portion from the upstream end to the middle of the transport direction, and the upstream side portion 85a1 is closer to the lower guide plate 85d toward the downstream side. The shape becomes smaller for a while, and the downstream portion 85a2 has a shape in which the intermediate portion protrudes toward the lower guide plate 85d so that the change in the distance from the lower guide plate 85d is relatively small toward the downstream end (the distance G0 is constant in the illustrated example). Is. According to such a shape, the seat P could be guided smoothly.

FIG. 10 is an explanatory diagram of the transport path switching member 85 according to the modified example. The transport path switching member 85 makes the gap of the transport path variable depending on the paper thickness. Specifically, the lower guide plate 85d is held by the pin 92 so as to be movable in the direction of spacing from the lower surface 85a, and a compression spring 93 is provided between the head of the pin 92 and the lower surface of the lower guide plate 85d and attached upward. It is gaining momentum. If the sheet P is stiff or the paper is thick, the sheet P advances while pushing down the lower guide plate 85d against the urging force of the compression spring 93 as shown in FIG. 10 (b). Can be done.

In the above embodiment, the transport path switching member 85 as the first guide member for switching the transport path for receiving the sheet from the upstream side between the transport path 54a which is the first transport path and the transport path 51a which is the second transport path. The present invention is applied, but the present invention is not limited to this, and the delivery destination of the sheet received in the first transport path is switched from the upper transport paths by changing the posture, or the sheet received in the first transport path. It can also be applied to one of the delivery destination transport paths in which the delivery angle is switched by changing the posture. Even in these cases, since the posture of the first guide member and the second guide member can be changed integrally, variations in the trajectory of the seat and the like can be suppressed as compared with the case where the second guide member is fixedly arranged. ..

Further, the present embodiment is applied to a place that can be evaluated as an image reading device including an image reading unit 80 and a transport path switching device 50 arranged downstream of the fixing device in the image forming device. It can also be applied to a part that can be evaluated as an image reading device including an image reading unit and a transport path switching device at another part of the forming device, or to such a device alone (for example, a document reading device alone). Example: A transport route switching device is provided on the downstream side of the transport path from the image reading unit, and this can be applied to a document reading device that can switch the ejection destination of a document after scanning between two or more locations.

The present invention can also be applied to a sheet transfer device that does not have an image reading unit. Even in such a sheet transporting device, variations in the track of the sheet can be suppressed as compared with a device in which the second guide member is fixedly arranged. Damage can be suppressed and rubbing noise can be reduced.

1: Optical writing unit 2: Process unit 3: Photoreceptor 4: Developing device 5: Charging device 6: Drum cleaning device 7: Paper feed device 30: Paper feed path 31: Pre-transfer transfer path 32: Manual feed feed path 33 : Bypass tray 34: Resist roller pair 35: Conveyor belt unit 36: Conveyor belt 37: Drive roller 38: Driven roller 40: Fixing device 50: Conveyance path switching device 51: Paper discharge path 51a: Conveyance path 52: Paper discharge roller pair 53: Paper discharge tray 54: Retransmission path 54a: Transfer path 55: Switchback path 56: Transfer path after switchback 57: Tray transfer path 58: Purge tray 58a: Bottom surface 58b: Top surface 60: Transfer unit 61: Intermediate transfer belt 62C: Primary transfer roller 62K: Primary transfer roller 62M: Primary transfer roller 62Y: Primary transfer roller 68: Secondary transfer backup roller 72: Secondary transfer roller 75: Belt cleaning device 80: Image reading unit 81: Upstream transfer Roller 82: Downstream transport roller 83: Downstream transport roller 84: Paper cooling device 85: Transport path switching member 85a: Bottom surface 85a1: Upstream side portion 85a2: Downstream side portion 85b: Top surface 85c: Rotating shaft 85d: Lower guide plate 86: Lower fixing guide 90: Upper fixing guide plate 91: Screw 92: Pin 93: Compression spring 100: Image forming apparatus 101: First paper cassette 101a: Paper roller 102: Second paper cassette 102a: Paper feeding Roller 103Y: Y toner bottle Ll: Reference pattern detection interval Lr: Reference pattern actual interval P: Sheet

Japanese Unexamined Patent Publication No. 2010-42521 Japanese Unexamined Patent Publication No. 2010-66516 JP-A-2017-90911

Claims (12)

In a seat guide device provided with a first guide member and a second guide member that sandwich the first transfer path of the sheet, and at least the posture of the first guide member can be changed.
A seat guide device characterized in that the posture can be changed by integrating the first guide member and the second guide member. In the seat guide device according to claim 1,
A seat guide device characterized in that the distance between the first guide member and the second guide member is variably configured. In the seat guide device according to claim 1 or 2.
The first guide member has a surface opposite to the second guide member and a third guide member that sandwiches the second transport path, and the seat is changed by changing the postures of the first guide member and the second guide member. A seat guide device characterized in that the transport path for receiving the vehicle can be switched between the first transport path and the second transport path. In the seat guide device according to claim 3,
It is the third transport path that includes the first transport path and the upstream guide member that constitutes the third transport path on the upstream side of the second transport path, and proceeds from the third transport path to the first transport path. A seat guide device characterized in that the degree of bending of the transport path is larger than that of proceeding to the second transport path. In the seat guide device according to claim 3 or 4.
A seat guide device characterized in that the guide surface of the first guide member on the first transport path side has a shape in which a portion in the middle of the first transport path projects toward the second guide member. In the seat guide device according to claim 5,
The distance between the guide surface on the first transport path side of the first guide member and the second guide member becomes smaller for a while from the upstream end to the middle part of the first transport path toward the downstream side. A seat guide device characterized in that a portion in the middle of the seat guide member has a shape protruding toward the second guide member so that the distance from the second guide member changes relatively little toward the downstream end. A sheet transfer device including the sheet guide device according to any one of claims 1 to 6 and an upstream sheet transfer means for transporting a sheet to be fed to the sheet guide device. In the sheet transport device according to claim 7,
A downstream sheet transporting means for transporting a sheet that has passed through the first transport path is provided.
A sheet transport device characterized in that the transport speed of the downstream sheet transport means is different from the transport speed of the upstream sheet transport means. In the sheet transport device according to claim 8,
A sheet transport device characterized in that the transport speed of the downstream sheet transport means is faster than the transport speed of the upstream sheet transport means. An image reading device having the sheet transport device according to any one of claims 7 to 9 and an image reading unit provided between the upstream sheet transport means and the first transport path. An image forming apparatus in which the image reading device according to claim 10 is provided at a position where an image of a sheet sent from a fixing device is read. The image forming apparatus according to claim 11, wherein the first conveying path is used as a conveying path leading to a conveying path for retransmission to the image forming unit.

Images