JP4184243B2 - Recording medium transport mechanism and image forming apparatus provided with the recording medium transport mechanism - Google Patents

Description

  The present invention relates to a recording medium transport mechanism provided in, for example, a paper discharge unit of an image forming apparatus and an image forming apparatus including the recording medium transport mechanism. In particular, the present invention relates to a measure for realizing switching of the recording medium conveyance mode with a compact configuration.

  Conventionally, as an image forming operation of an electrophotographic image forming apparatus such as a color printer, an electrostatic latent image is formed on a photosensitive drum based on received image data. Then, toner is attached to the electrostatic latent image, and the image data is visualized on the photosensitive drum. Thereafter, the toner image on the photosensitive drum is transferred to the recording paper conveyed through the paper conveyance path. This transfer method includes a method in which the toner image on the photosensitive drum is directly transferred to the recording paper, or the toner image on the photosensitive drum is temporarily transferred to the intermediate transfer belt (primary transfer), and then the intermediate image is transferred to the intermediate transfer belt. A system for transferring (secondary transfer) a toner image on a transfer belt onto a recording sheet is known. Then, the recording paper on which the toner image is transferred is passed through a fixing roller, and the toner image is fixed on the recording paper by heating and pressurizing with the fixing roller. The recording paper on which image formation has been performed in this manner is then discharged onto a paper discharge tray via a paper discharge path.

The following Patent Document 1 discloses an image forming apparatus of this type. In Patent Document 1, a gate unit is provided at a junction between a first conveyance path, which is a path on the paper discharge side of the fixing roller, and a second conveyance path having first and second paper discharge ports. Is disclosed. By this switching operation of the gate means, the conveyance mode in which the sheet sent from the first conveyance path is guided to the first sheet discharge port, and the sheet is fed to the second sheet discharge port when the sheet is switched back. The transport mode to be sent can be switched.
JP 2002-37500 A

  By the way, as disclosed in the above-mentioned Patent Document 1, in the case where a conveyance path in which only the second conveyance path is communicated with the first conveyance path is provided, it has been known that it has been conventionally known. It is possible to switch the conveyance form using a gate means (one kind of crescent moon type) having a simple structure.

  However, in recent years, for example, an image forming apparatus called a “job separator unit”, which is equipped with a paper discharge unit other than a paper discharge tray as an option, has been increasing, and a paper discharge unit structure including four or more conveyance paths. Is being demanded. As an example of the paper discharge path, a first transport path which is a path on the paper discharge side of the fixing roller, a second transport path toward the paper discharge tray, a third transport path toward the job separator unit, and a switchback transport path There is a paper discharge path having a configuration in which the path ends connected to each other are connected to each other by a junction.

  In the paper discharge path having such a configuration, when the paper conveyance mode is selectively switched (for example, the conveyance mode in which the recording paper is conveyed from the first conveyance path to the second conveyance path, the fourth conveyance path to the fourth conveyance path). The conventional gate means cannot cope with the case where the conveyance mode for conveying the recording paper to the conveyance path and the conveyance mode for conveying the recording paper from the first conveyance path to the third conveyance path) can be switched. In order to cope with this, it is conceivable to provide an individual gate member for each conveyance path, but this leads to a complicated configuration and an increase in size of the paper discharge portion.

  The present invention has been made in view of such points, and an object of the present invention is to realize a selective switching of the paper transport mode in a paper discharge portion having four or more transport paths. An object of the present invention is to provide a recording medium transport mechanism and an image forming apparatus including the recording medium transport mechanism.

-Summary of invention-
In order to achieve the above object, the solution of the present invention is configured so that the two types of gate members can selectively switch the sheet conveyance mode in the sheet discharge portion having four or more conveyance paths. did. For example, a recording medium conveyance path is formed between the two types of gate members, and the posture of the gate members is changed to selectively switch the sheet conveyance mode.

-Solution-
Specifically, the present invention has at least first to fourth conveyance paths whose conveying ends communicate with each other through a junction as conveyance paths for conveying a recording medium, and from one conveyance path to another one conveyance It is premised on a recording medium transport mechanism that can selectively switch a plurality of transport modes for transporting a recording medium over a path. With respect to this recording medium conveyance mechanism, the first to fourth conveyance paths are configured as cross-shaped conveyance paths whose path ends communicate with each other at the junction, and the first to fourth conveyance paths Among these, the second conveyance path is a conveyance path that conveys the recording medium conveyed from the first conveyance path toward the paper discharge tray of the image forming apparatus, and the third conveyance path is the first conveyance path. This is a transport path for transporting the recording medium transported from the path toward an accessory device such as a job separator unit, which is a paper discharge unit different from the paper discharge tray. The fourth transport path is a second transport once. A conveyance path that conveys the recording medium guided to the path toward a switchback conveyance path for backside printing, and is configured so that the plurality of conveyance modes can be selectively switched to the junction. First and second gate members configured to be changeable They are allowed provided.

  By this specific matter, for example, among the first to fourth transport paths, the transport mode for transporting the recording medium from the first transport path to the second transport path, and the recording medium is transported from the first transport path to the third transport path. The postures of the first and second gate members can be made different from those in the transport mode, and the transport destination of the recording medium sent out from the first transport path can be switched. Further, even in the transport mode using the fourth transport path, the recording medium can be sent to the fourth transport path by changing the posture of the gate member. Thus, it becomes possible to realize switching of a plurality of transport modes using the first to fourth transport paths only by providing two types of gate members, and the operating range of the gate members can be reduced. A small space is sufficient for installing the gate member. As a result, it is possible to realize selective switching of the paper transport mode with a compact configuration.

Further, the specific configuration of each gate member is as follows. First, the first gate member and the second gate member are connected by a connecting means so as to change the posture in conjunction with each other. According to this, since it becomes possible to change the posture of each gate member with the same drive source, the transport mechanism can be made more compact than when each gate member is provided with a dedicated drive source. . In addition, since it is not necessary to control each gate member individually, it is possible to facilitate the control operation, and it is possible to prevent the occurrence of a transport error and a paper jam due to a malfunction of the switching timing.
Further, a configuration for positioning the posture of the gate member is described below. In other words, a restriction member that restricts the change in the posture of the gate member is provided, and the posture of the gate member can be changed by moving the restriction member.
With this specific matter, the posture of each gate member changes with the movement of the restricting member, and the transfer mode can be selectively switched.
Further, the first gate member is configured to be able to introduce the recording medium from the first conveying path to the second conveying path, and the recording medium is placed in the space between the second gate member. While being configured to function as a guide plate that guides the second back path to switch back transport from the second transport path to the fourth transport path, the recording medium is in the space between the second gate member Is configured to function as a guide plate that leads from the first conveyance path to the third conveyance path, and the second gate member is a recording medium in a space between the first gate member and the recording medium. Is configured to function as a guide plate that leads to switchback conveyance from the second conveyance path to the fourth conveyance path, while recording in the space between the first gate member By letting the medium pass, And it has a configuration that functions as a guide plate for guiding to the conveying path.
With this specific matter, in at least one of the plurality of transport modes for transporting the recording medium from one transport path to another transport path, the first gate member and the second gate member The recording medium can pass through the space. In this way, each gate member itself functions as a guide plate that forms a conveyance path, so that switching of the conveyance mode can be performed reliably, erroneous conveyance can be prevented, and stable recording medium conveyance operation can be performed. it can.

  Further, the posture is changed by rotating the first and second gate members about the rotation axis. Then, the rotation axis of the first gate member and the rotation axis of the second gate member are opposed to each other in a direction different from the extending direction of each conveyance path, and a junction portion at the path end of each conveyance path is interposed therebetween. Set to the pinch position. According to this, for example, when the first conveyance path and the third conveyance path communicate in the vertical direction and the second conveyance path and the fourth conveyance path communicate in the horizontal direction. If each gate member is rotated so as to extend in the horizontal direction, the second conveyance path and the fourth conveyance path are communicated in the horizontal direction, and the first conveyance path and the third conveyance path are closed. On the other hand, if each gate member is rotated so as to extend in the vertical direction, the first conveyance path and the third conveyance path communicate with each other in the vertical direction, and the second conveyance path and the fourth conveyance path are closed. . In this way, it is possible to selectively switch the transport mode with a relatively simple operation such as a rotation operation of each gate member.

  The following can be listed as a configuration for carrying the recording medium more stably. That is, when the recording medium is transported from one transport path to another transport path, the first gate member and the second gate member close the transport paths other than the two transport paths. The posture is changed. According to this, it is possible to surely prevent the recording medium from being erroneously conveyed to a conveyance path that does not require conveyance of the recording medium, and to improve the reliability of the conveyance operation.

  As a configuration for transporting the recording medium without using the space between the first gate member and the second gate member as a path for passing the recording medium, the following can be mentioned. In other words, in the conveyance mode in which the recording medium is conveyed from the first conveyance path to the second conveyance path, an urging unit that applies an urging force in the direction of closing the second conveyance path to the first gate member is provided. It is a configuration. At this time, when the recording medium passes from the first conveyance path to the second conveyance path, the recording medium pushes the first gate member against the urging force of the urging means and introduces it into the second conveyance path. It has come to be.

  Due to these specific matters, when the recording medium passes from the first conveying path to the second conveying path, the recording medium is sandwiched between the first gate member and the inner wall of the second conveying path. , Generation of abnormal noise during conveyance can be suppressed. In particular, it is possible to prevent so-called “sound noise” that occurs when the upstream end (rear end) in the transport direction of the recording medium is struck against the inner wall of the second transport path. Further, in this state, the first gate member receives the biasing force from the biasing means and is pressed against the inner wall of the second transport path, so that it does not protrude toward the center of the second transport path. For this reason, on the back side of the first gate member (on the side opposite to the inner wall of the second conveyance path with which the first gate member abuts), the second conveyance path is another conveyance path (for example, the fourth conveyance path). In this state, if the recording medium is transported from the second transport path to another transport path, the recording medium can pass without being caught by the first gate member.

In addition, a restricting member is provided on the urging direction side of the urging means, and the movement of the first gate member is not restricted in the reverse direction (the direction against the urging force). The operation is performed smoothly.

  Specifically, as the relationship between the posture of the gate member and the communication state of the conveyance path, first, the posture of the first and second gate members can be changed between the first posture and the second posture. . When each gate member is in the first posture, the recording medium can be conveyed from the first conveying path to the second conveying path, and the recording medium can be conveyed from the second conveying path to the fourth conveying path. It is configured. At this time, that is, when each gate member is in the first posture, the third conveyance path is closed.

By this specific matter, the recording medium transport from the first transport path to the second transport path and the recording medium transport from the second transport path to the fourth transport path can be ensured simply by switching the transport direction of the recording medium. Can be carried out and erroneous conveyance can be prevented. In particular, the third conveyance path, are used as a transport path for transporting the recording medium in the accessory device (optional device such as a job separator unit described above), a third state in which the optional device is not mounted Since the conveyance path can be closed, an appropriate recording medium conveyance form can be obtained.

  When the accessory device (such as a job separator unit) is provided with a drive source for changing the posture of each gate member so as to convey the recording medium to the third conveyance path, the accessory device is mounted. Only in this case, the recording medium can be conveyed to the third conveyance path. In other words, when the main body side (base machine) of the image forming apparatus is not equipped with a drive source for the accessory device, the accessory device is mounted while simplifying the configuration of the device and reducing the manufacturing cost. Therefore, it is possible to construct a configuration that can change the posture of each gate member for transporting the recording medium to the third transport path.

  Note that an image forming apparatus including a recording medium conveyance mechanism according to any one of the above-described solutions is also within the scope of the technical idea of the present invention. In other words, an image forming unit that forms an image on the recording medium is provided, and the recording medium on which the image is formed in the image forming unit is changed to the first and second gate members in accordance with the change in posture of the first and second gate members. An image forming apparatus configured to be transported and discharged from one transport path among the fourth transport paths to the other transport path.

  In the present invention, the two types of gate members can be used to selectively switch the paper conveyance mode in a paper discharge portion having four or more conveyance paths. For this reason, it is possible to selectively switch the paper conveyance mode (selective switching of the paper conveyance mode in the paper discharge portion having four or more conveyance paths) that could not be handled by the conventional gate means. become. In addition, since the switching can be performed with only two types of gate members, the operating range of the gate members can be reduced, and a space for installing the gate members can be small. As a result, it is possible to realize selective switching of the paper transport mode with a compact configuration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a case where the present invention is applied to a color printer will be described.

(Description of overall configuration of image forming apparatus)
FIG. 1 schematically shows the internal configuration of the image forming apparatus according to the present embodiment. The image forming apparatus forms a multicolor (full color) image or a single color (monochrome) image on a predetermined sheet (recording paper) in accordance with image data transmitted from the outside (for example, a terminal device such as a personal computer). To do. As shown, the image forming apparatus includes an exposure unit 1, a developing device 2 (2a to 2d), a photosensitive drum 3 (3a to 3d), a charger 5 (5a to 5d), and a cleaner unit 4 (4a). 4d), the intermediate transfer belt unit 8, the fixing device 12, the paper transport path S, the paper feed cassette 10, the paper discharge tray 15, and the like.

  Note that image data handled in the image forming apparatus corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Accordingly, the developing device 2 (2a to 2d), the photosensitive drum 3 (3a to 3d), the charger 5 (5a to 5d), and the cleaner unit 4 (4a to 4d) generate four types of latent images corresponding to the respective colors. In FIG. 1, four image stations are provided, each having a set to black, b set to cyan, c set to magenta, and d set to yellow.

  The photosensitive drum 3 is disposed (mounted) on the upper part of the image forming apparatus, and an electrostatic latent image corresponding to image data is formed by laser light irradiation from the exposure unit 1 as will be described later. .

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. As shown in FIG. 1, in addition to a contact type roller type or brush type charger, a charger type charger is used. A charger may be used.

  The exposure unit 1 includes a laser scanning unit (LSU) including a laser irradiation unit 1A and reflection mirrors 1B, 1B,. The laser irradiation unit 1A irradiates laser light for each hue based on the received image data. In addition, there is a method using, for example, an EL or LED writing head in which light emitting elements are arranged in an array. The exposure unit 1 has a function of forming an electrostatic latent image corresponding to the image data on the surface of the photosensitive drum by exposing the charged photosensitive drum 3 according to the input image data. Have.

  The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toners of respective colors (K, C, M, Y).

  The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The intermediate transfer belt unit 8 disposed above the photosensitive drum 3 includes an intermediate transfer belt 7, an intermediate transfer belt drive roller 71, an intermediate transfer belt tension mechanism 73, an intermediate transfer belt driven roller 72, and a primary transfer roller. An intermediate transfer roller 6 (6a to 6d) and an intermediate transfer belt cleaning unit 9 are provided.

  The intermediate transfer belt drive roller 71, the intermediate transfer belt tension mechanism 73, the intermediate transfer roller 6, and the intermediate transfer belt driven roller 72 are stretched over the intermediate transfer belt 7, and the intermediate transfer belt 71 is rotated along with the rotation of the intermediate transfer belt drive roller 71. The belt 7 travels in the direction of arrow B.

  The intermediate transfer roller 6 is rotatably supported by a roller mounting portion in the intermediate transfer belt tension mechanism 73. As a result, the intermediate transfer rollers 6 a to 6 d are rotatably disposed on the inner surface side of the intermediate transfer belt 7 facing each photoconductor drum 3, and the toner image on the photoconductor drum 3 is also provided. Is transferred to the intermediate transfer belt 7.

  The intermediate transfer belt 7 is provided so as to be in contact with each photosensitive drum 3. Then, the toner images of the respective colors formed on the photosensitive drum 3 are sequentially superimposed and transferred onto the intermediate transfer belt 7, thereby forming a color toner image (multicolor toner composite image) on the intermediate transfer belt 7. It is like that. The intermediate transfer belt 7 is endlessly formed using a film having a thickness of about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by the intermediate transfer roller 6 in contact with the back side (inner surface side) of the intermediate transfer belt 7. That is, a high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charge polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image. The intermediate transfer roller 6 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 7. In this embodiment, a roller electrode is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the toner images visualized according to the hues on the photoreceptors 3a to 3d are stacked on the intermediate transfer belt 7 and become image information input to the apparatus. In this way, the laminated image information (composite image of multi-color toner) is transferred to a transfer roller that constitutes a transfer unit that is disposed at a contact position between a later-described sheet and the intermediate transfer belt 7 as the intermediate transfer belt 7 travels. 11 is transferred onto the paper.

  At this time, the intermediate transfer belt 7 and the transfer roller 11 are pressed against each other at a predetermined nip, and a voltage for transferring the toner onto the sheet is applied to the transfer roller 11 (opposite to the charging polarity (−) of the toner). Polarity (+) high voltage). Further, in order to obtain the nip constantly, the transfer roller 11 uses either the transfer roller 11 or the intermediate transfer belt drive roller 71 as a hard material (metal or the like) and the other as a soft material (elasticity such as an elastic roller). Rubber roller or foaming resin roller).

  Further, as described above, the toner adhered to the intermediate transfer belt 7 due to contact with the photosensitive drum 3 or the toner that is not transferred onto the sheet by the transfer roller 11 and remains on the intermediate transfer belt 7 Therefore, the intermediate transfer belt cleaning unit 9 removes and collects the toner. The intermediate transfer belt cleaning unit 9 includes a cleaning blade 91 as a cleaning member that comes into contact with the intermediate transfer belt 7. The intermediate transfer belt 7 contacts the intermediate transfer belt 7 in contact with the cleaning blade 91 from the back side. It is supported by a driven roller 72. The residual toner collected by the cleaning blade 91 falls and accumulates in a storage unit 92 installed below the cleaning blade 91.

  The paper feed cassette 10 is a cassette for storing sheets (recording paper) used for image formation, and is provided at the bottom of the image forming apparatus, that is, below the exposure unit 1. A paper discharge tray 15 provided in the upper part of the image forming apparatus is a tray for placing printed sheets face down.

  Further, the image forming apparatus is provided with a sheet conveyance path S for sending the sheet of the sheet feeding cassette 10 to the sheet discharge tray 15 via the transfer roller 11 and the fixing device 12. The paper transport path S extends in a substantially vertical direction from the paper discharge unit of the paper feed cassette 10 toward the paper discharge tray 15. Further, a pickup roller 16 (16-1), a registration roller 14, a transfer roller 11, a fixing device 12, and a conveyance roller 25 (25) that conveys a sheet are provided in a paper conveyance path S from the paper cassette 10 to the paper discharge tray 15. -1,25-2, 25-3) and the like are disposed.

  The conveyance rollers 25 are small rollers for promoting and assisting conveyance of the sheet, and a plurality of conveyance rollers 25 are provided along the sheet conveyance path S. The pickup roller 16 is a drawing roller that is provided at the end of the paper feed cassette 10 and that feeds sheets one by one from the paper feed cassette 10 to the paper transport path S.

  Further, the registration roller 14 temporarily holds the sheet being conveyed on the sheet conveyance path S. The sheet has a function of conveying the sheet to a transfer unit (a nip portion between the transfer roller 11 and the intermediate transfer belt driving roller 71) at the timing when the leading edge of the toner image on the intermediate transfer belt 7 is aligned with the leading edge of the sheet. Yes.

  The fixing device 12 includes a heat roller 31, a pressure roller 32, and the like, and the heat roller 31 and the pressure roller 32 rotate with a sheet interposed therebetween. The heat roller 31 is set by the control unit to have a predetermined fixing temperature based on a signal from a temperature detector (not shown), and is transferred to the sheet by thermocompression bonding the sheet together with the pressure roller 32. The resulting multicolor toner image is melted, mixed, and pressed to thermally fix the sheet.

  The sheet after the fixing of the multicolor toner image is transported on the paper transport path S by the transport rollers 25, and is discharged onto the paper discharge tray 15 with the multicolor toner image facing downward. (When the job separator unit described later is not installed).

  Next, the sheet conveyance path will be described in detail. The image forming apparatus is provided with a paper feed cassette 10 that stores sheets in advance, and a manual feed tray 20 that does not need to open and close the paper feed cassette 10 when a user prints a small number of sheets. ing.

  In both paper feeding methods, pickup rollers 16 (16-1 and 16-2) are arranged, respectively, so as to guide one sheet to the conveyance path.

  The sheet conveyed from the sheet feeding cassette 10 is conveyed to the registration roller 14 by the conveying roller 25-1 in the conveying path, and is transferred to the transfer roller 11 at a timing when the leading edge of the sheet and the leading edge of the image information on the intermediate transfer belt 7 are aligned. The image information is written on the sheet. Thereafter, the sheet passes through the fixing device 12, whereby unfixed toner on the sheet is melted and fixed by heat, and is discharged from the discharge roller 25-3 onto the discharge tray 15 through the conveyance roller 25-2 ( (When requesting single-sided printing)

  On the other hand, the sheets stacked on the manual feed tray 20 are fed by the pickup roller 16-2, reach the registration roller 14 through a plurality of transport rollers (25-6, 25-5, 25-4), and thereafter. The sheet is discharged from the sheet feeding cassette 10 to the sheet discharge tray 15 through the same process as that of the sheet fed (when single-side printing is requested).

  At this time, if the print request content is a double-sided print request, the trailing edge of the sheet that has finished single-sided printing and passed through the fixing device 12 as described above is chucked by the paper discharge roller 25-3, and the paper discharge roller 25 -3 reversely rotates and is guided to the switchback conveyance path S1 provided with the conveyance rollers (25-7, 25-8), then the back side printing is performed through the registration rollers 14, and then the paper discharge tray. 15 will be discharged.

  In the actual image forming operation, the intermediate transfer roller 6 is subjected to intermediate transfer in response to a print request in order to reduce deterioration of the photosensitive drum 3 due to contact between the intermediate transfer belt 7 and the photosensitive drum 3. The intermediate transfer belt 7 and the photosensitive drum 3 can be separated from each other by moving the belt 7 in a direction in which the belt 7 is in contact with or separated from the belt 7.

  That is, the print request includes a color mode and a monochrome mode. In the color mode, each intermediate transfer roller 6 (6a to 6d) moves so as to come into contact with the back surface of the intermediate transfer belt 7, thereby performing the intermediate transfer. The surface of the belt 7 and each of the photosensitive drums 3 (3a to 3d) come into contact with each other so that the toner image of each hue can be primarily transferred to the intermediate transfer belt 7. On the other hand, in the monochrome mode, only the intermediate transfer roller 6a for black image formation moves so as to come into contact with the back surface of the intermediate transfer belt 7, thereby the surface of the intermediate transfer belt 7 and the photosensitive drum for black image formation. 3a comes into contact with the black toner image so that it can be primarily transferred to the intermediate transfer belt 7.

(Description of paper discharge mechanism)
Next, the paper discharge mechanism 50 that is a feature of this embodiment will be described. The paper discharge mechanism 50 is disposed on the downstream side (upper side in FIG. 1) of the fixing device 12 and further on the downstream side (upper side in FIG. 1) of the conveying roller 25-2. Hereinafter, the paper discharge mechanism 50 will be described in detail with reference to FIGS. 2 is a side view showing a schematic configuration of the paper discharge mechanism 50, FIG. 3 is a perspective view of the paper discharge mechanism 50, FIG. 4 is a cross-sectional view showing a drive mechanism 65 provided in the paper discharge mechanism 50, and FIG. FIG. 6 is a view showing the connection state of the gate members 61 and 62, and FIG. 6 is a view showing the operation of the gate members 61 and 62. 7 shows a state when paper is discharged to the paper discharge tray 15, FIG. 8 shows a state when paper is discharged to the switchback conveyance path S1, and FIG. 9 shows a state when paper is discharged to the job separator unit 80 described later. Indicates the state.

  As shown in these drawings, the paper discharge mechanism 50 includes a first conveyance path 51 that extends vertically upward from the downstream side of the fixing device 12 and the conveyance roller 25-2, and a second conveyance path 52 that extends toward the paper discharge tray 15. , A third transport path 53 directed to a job separator 80 described later, and a fourth transport path 54 connected to the switchback transport path S1 are provided. The path ends of the transport paths 51 to 54 are communicated with each other at the junction A. That is, the first conveyance path 51 and the third conveyance path 53 communicate with each other in the vertical direction, and the second conveyance path 52 and the fourth conveyance path 54 communicate with each other in the horizontal direction. Yes.

  In other words, the transport paths 51 to 54 are formed by four transport guides 55 to 58 that are independent from each other, and the first guide 55 is located on the lower right side (the side close to the paper discharge tray 15) in FIG. And the second guide 56 located on the left side (switchback conveyance path S1 side) of the first conveyance path 51, the first guide 55 and the third guide 57 located on the upper side (job separator unit 80 side). Thus, the second transport path 52 is formed by the third guide 57 and the fourth guide 58 located on the left side (switchback transport path S1 side), so that the third transport path 53 is formed by the second guide 56 and the fourth guide 58. Thus, the fourth transport path 54 is formed. In addition, the corner | angular part which faces the merge part A in the said 1st guide 55 is formed in the curved surface 55a so that conveyance of the recording paper from the 1st conveyance path 51 to the 2nd conveyance path 52 can be performed smoothly.

  Next, the gate members 61 and 62 for switching the communication state of the transport paths 51 to 54 will be described. The paper discharge mechanism 50 of the present embodiment includes first and second types of gate members 61 and 62. The first gate member 61 is a plate material having a substantially triangular shape in a side view, and a side 61a facing the curved surface 55a of the first guide 55 is curved in a concave shape. The curved side 61 a guides the sheet conveyance from the first conveyance path 51 to the second conveyance path 52. On the other hand, the second gate member 62 is a plate material having a substantially rectangular shape in a side view.

  Each of these gate members 61 and 62 is supported so as to be rotatable around a horizontal axis (axis perpendicular to the paper surface of FIG. 2) in the vicinity of the junction A of each of the transport paths 51 to 54. Specifically, shafts 63 and 64 extending in the horizontal direction are disposed on the first guide 55 side and the fourth guide 58 side with respect to the center point of the merging portion A, respectively. As shown in FIG. 3, the first shaft 63 on the first guide 55 side is provided with a plurality of first gate members 61, 61, 61 that are pivotally integrated with a predetermined interval in the shaft extending direction. Yes. On the other hand, the second shaft 64 on the fourth guide 58 side is provided with a plurality of second gate members 62, 62, 62 which are integrally rotated at predetermined intervals in the shaft extending direction.

  Both end portions of the shafts 63 and 64 are rotatably supported by frames F1 and F2 of the image forming apparatus, and a drive mechanism 65 is provided on the shaft end side of one (the back side in FIG. 3) and the other (FIG. 3). A connecting mechanism 66 is provided on each of the shaft ends on the front side in FIG. Hereinafter, the drive mechanism 65 and the linkage mechanism 66 will be described.

  The drive mechanism 65 provided on one shaft end side includes a position restriction board 65a that is externally attached to the first shaft 63, an electromagnetic solenoid 65b that is a drive source for obtaining the rotational force of the position restriction board 65a, and the electromagnetic solenoid. A sector gear member 65c for transmitting the driving force of 65b to the position regulating board 65a is provided.

  The position restricting plate 65a is formed with an insertion hole having an inner diameter substantially matching the outer diameter of the first shaft 63 at the center, and the shaft end portion of the first shaft 63 is inserted into the insertion hole (position restricting plate). It can be rotated relative to 65a (inserted freely). Further, the first shaft 63 is provided with a locking pin 63a extending outward. A tension coil spring 63b is spanned between the locking pin 63a and a device frame (not shown), and a downward biasing force is applied by the coil spring 63b. Thereby, the urging force in the clockwise direction in FIG. 2 is applied to the first shaft 63. This urging force acts in a direction in which the lower end portion of the first gate member 61 is brought into contact with the first guide 55.

  On the other hand, a position restricting pin 65d extending in parallel with the axial direction of the position restricting plate 65a is projected. The protruding position of the position restricting pin 65d is set to a position where the lower end portion of the first gate member 61 is in contact with the lower end of the locking pin 63a in a state where the lower end portion is in contact with the first guide 55 (FIG. 3 and FIG. 3). 6 (a) state reference). That is, when the position restricting board 65a is rotated from this state and the position restricting pin 65d is moved upward, the locking pin 63a is also moved upward, whereby the first shaft 63 is rotated counterclockwise in FIG. The lower end of the first gate member 61 is separated from the first guide 55 by rotating. FIG. 6B shows a state where the first shaft 63 is rotated by 90 °.

  The sector gear member 65c is rotatably supported by a device frame (not shown) at the center in the longitudinal direction (vertical direction). The sector gear member 65c has a gear 65f formed at the lower end thereof, and the gear 65f meshes with a pinion gear 65e formed integrally with the position restricting board 65a so as to be able to transmit power. Further, the upper end of the sector gear member 65c is connected to the drive rod 65g of the electromagnetic solenoid 65b. In this way, the electromagnetic solenoid 65b and the position restricting board 65a are connected by the sector gear member 65c, and the sector gear member 65c falls within a predetermined angular range as the drive rod 65g moves in and out as the electromagnetic solenoid 65b operates. The position regulating board 65a is rotated along with this rocking to regulate the position of the first gate member 61.

  The linkage mechanism 66 provided on the other shaft end side of the shafts 63 and 64 is configured by three gears 66a, 66b, and 66c disposed on the outer surface side of the frame F2. That is, the first gear 66a attached to the first shaft 63 integrally with the rotation, the second gear 66b attached to the second shaft 64 integrally with the rotation, and the third gear 66a and the second gear 66b connected to each other. It is comprised by the gear 66c. Since the linkage mechanism 66 is thus configured, the rotational force of the first shaft 63 accompanying the operation of the electromagnetic solenoid 65b is transmitted to the second shaft 64, whereby the first shaft 63, the second shaft 64, Are configured to rotate in the same direction. As a result, the first gate member 61 and the second gate member 62 also rotate in the same direction. Thus, since it is possible to change the posture of each gate member 61, 62 by the electromagnetic solenoid 65b which is a common drive source, the configuration is compared with the case where each gate member 61, 62 is provided with a dedicated drive source. Can be made more compact.

  FIG. 6 shows a state in which the first gate member 61 and the second gate member 62 are rotated to change the posture in accordance with the operation of the electromagnetic solenoid 65b. FIG. 6A shows a state in which the drive rod 65g of the electromagnetic solenoid 65b protrudes, and the lower end portion of the first gate member 61 abuts on the first guide 55, and the upper surface of the first gate member 61 and the second gate. In this state, a communication path that connects the second transport path 52 and the fourth transport path 54 is formed between the lower surface of the member 62. Hereinafter, the posture of each of the gate members 61 and 62 in this state is referred to as a first posture.

  FIG. 6B shows a state in which the drive rod 65g of the electromagnetic solenoid 65b is immersed, and the first gate member 61 and the second gate member 62 are both turned counterclockwise by 90 °. In this state, the first transport path 51 and the third transport path 53 are communicated between the side surface (left side surface in the figure) of the first gate member 61 and the side surface (right side surface in the figure) of the second gate member 61. The communication path to be formed is formed. Hereinafter, the posture of each of the gate members 61 and 62 in this state is referred to as a second posture. In this way, the first gate member 61 and the second gate member 62 change their postures in accordance with the operation of the electromagnetic solenoid 65b, so that the communication states of the transport paths 51 to 55 can be switched.

  6A, the lower end portion of the first gate member 61 is pressed against the first guide 55 by the urging force of the coil spring 63b. In this state, when the recording sheet passes from the first conveying path 51 to the second conveying path 52, the recording sheet pushes the first gate member 61 upward against the urging force of the coil spring 63b, and the second sheet The second conveyance path 52 is opened, and the recording paper can be introduced into the second conveyance path 52. FIG. 7 shows the postures of the gate members 61 and 62 when the recording paper is conveyed from the first conveyance path 51 to the second conveyance path 52. The alternate long and short dash line indicates the conveyance path of the recording paper. Thus, the recording sheet pushes the first gate member 61 upward and is introduced into the second transport path 52. In this case, since the third transport path 53 is closed by the second gate member 62, erroneous transport to the third transport path 53 does not occur. Further, during this conveyance, the recording sheet is conveyed while being sandwiched between the first gate member 61 and the inner wall of the second conveyance path 52 (the curved surface 55a of the first guide 55). Sound generation can be suppressed. In particular, it is possible to prevent a so-called “sound” that occurs when the upstream end (rear end) in the conveyance direction of the recording paper is struck against the inner wall or the like of the second conveyance path 52.

  On the other hand, when the recording paper is transported to the switchback transport path S1 in response to the double-sided printing request, it is necessary to transport the recording paper once transported to the second transport path 52 to the second transport path 52. In addition, the gate members 61 and 62 are in the first posture shown in FIG. As a result, a communication path that connects the second transfer path 52 and the fourth transfer path 54 is formed between the upper surface of the first gate member 61 and the lower surface of the second gate member 62, and the switch The recording paper can be smoothly conveyed to the back conveyance path S1. FIG. 8 shows the postures of the gate members 61 and 62 when the recording paper is conveyed from the second conveyance path 52 to the fourth conveyance path 54. The alternate long and short dash line indicates the conveyance path of the recording paper. Also in this case, since the third transport path 53 is closed by the second gate member 62, erroneous transport to the third transport path 53 does not occur. In this state, the first gate member 61 receives the biasing force from the coil spring 63b and is pressed against the inner wall (the curved surface 55a of the first guide 55) of the second conveyance path 52, so that the second conveyance path 52 does not protrude to the center side. For this reason, the second transport path 52 communicates with the fourth transport path 54 on the back side of the first gate member 61 (upper surface side in the state of FIG. 8). If the recording sheet is conveyed to the conveying path 54, the recording sheet can pass without being caught by the first gate member 61.

  Further, when the recording paper is discharged to the job separator unit 80 in response to a paper discharge request to the job separator unit 80, the recording paper needs to be transported from the first transport path 51 to the third transport path 53. In some cases, the gate members 61 and 62 are in the second posture shown in FIG. Accordingly, the first conveyance path 51 and the third conveyance path 53 are communicated between the side surface (left side surface in the drawing) of the first gate member 61 and the side surface (right side surface in the drawing) of the second gate member 61. As a result, the recording sheet can be smoothly conveyed to the job separator unit 80. FIG. 9 shows the postures of the gate members 61 and 62 when the recording paper is conveyed from the first conveyance path 51 to the third conveyance path 53. The alternate long and short dash line indicates the conveyance path of the recording paper. In this case, the second transport path 52 is closed by the first gate member 61 and the fourth transport path 54 is closed by the second gate member 62, so that the second transport path 52 and the fourth transport path 51 are connected to each other. Incorrect conveyance will not occur.

  Further, the recording paper conveyed to the job separator unit 80 in this way is selected from one of the two systems of conveyance paths provided in the job separator unit 80 and discharged from the job separator unit 80. It has become. In other words, inside the job separator unit 80, the conveyance roller 81 that conveys the recording sheet introduced from the third conveyance path 53, and the rotation of feeding the recording sheet to one side selected by the user among the two conveyance paths. A movable switching mechanism 82 is provided, and discharge rollers 83 and 84 provided in the respective transport paths for discharging the recording paper sent from the switching mechanism 82 from the job separator unit 80 are provided.

  As described above, according to the present embodiment, among the first to fourth transport paths 51 to 54, the recording sheet is transported from the first transport path 51 to the second transport path 52, and from the second transport path 52. Only the postures of the two types of gate members 61 and 62 are different from each other in the form of transport of the recording paper to the fourth transport path 54 and the form of transport of the recording medium from the first transport path 51 to the third transport path 53. Can be switched. For this reason, the operation range of the gate members 61 and 62 can be reduced, and the space for installing the gate members 61 and 62 can be small. As a result, it is possible to realize selective switching of the paper transport mode with a compact configuration.

-Other examples-
In each of the embodiments described above, the case where the present invention is applied to an image forming apparatus configured as a color printer has been described. The present invention is not limited to this, and can also be applied to an image forming apparatus configured as a color copier or an image forming apparatus configured as a multi-function machine having a plurality of functions.

  In the above-described embodiment, the case where the paper discharge mechanism 50 according to the present invention is applied to a paper discharge unit having four conveyance paths communicating in a cross shape has been described. It is also applicable to.

1 is a diagram illustrating an internal configuration of an image forming apparatus according to an embodiment. It is a side view which shows schematic structure of a paper discharge mechanism. It is a perspective view of a paper discharge mechanism. It is sectional drawing which shows the drive mechanism with which the paper discharge mechanism was equipped. FIG. 3 is a view corresponding to FIG. 2 showing a state in which the gate members are connected to each other. It is a figure which shows operation | movement of each gate member. FIG. 3 is a view corresponding to FIG. 2 showing a state when paper is discharged to a paper discharge tray. FIG. 3 is a view corresponding to FIG. 2 and illustrating a state when paper is discharged to a switchback conveyance path. FIG. 3 is a view corresponding to FIG. 2 showing a state when paper is discharged to a job separator unit.

Explanation of symbols

50 Paper discharge mechanism (recording medium transport mechanism)
51 1st conveyance path 52 2nd conveyance path 53 3rd conveyance path 54 4th conveyance path 61 1st gate member 62 2nd gate member 63 1st shaft 63b Coil spring (biasing means)
64 Second shaft 65b Electromagnetic solenoid (drive source)
65d Position restriction pin (regulation member)
A Junction

Claims (9)

As the transport path for transporting the recording medium, each of the path ends has at least first to fourth transport paths that communicate with each other through a junction, and the recording medium is transported from one transport path to another transport path. A recording medium transport mechanism capable of selectively switching a plurality of transport modes,
The first to fourth transport paths are configured as cross-shaped transport paths whose path ends communicate with each other at the junction, and among the first to fourth transport paths, the second transport path is , A conveyance path that conveys the recording medium conveyed from the first conveyance path toward the paper discharge tray of the image forming apparatus, and the third conveyance path is a recording medium conveyed from the first conveyance path. Is a transport path that transports the recording medium toward an accessory device such as a job separator unit that is a separate paper discharge unit from the paper discharge tray, and the fourth transport path is a recording medium that is once guided to the second transport path Is a transport path that transports toward the switchback transport path for backside printing,
The merging portion is provided with first and second gate members configured to be capable of changing the posture so that the plurality of transfer modes can be selectively switched.
The first gate member is configured to be able to introduce the recording medium from the first conveyance path to the second conveyance path, and allows the recording medium to pass through the space between the second gate member. Therefore, the recording medium passes through the space between the second gate member and the second gate member while functioning as a guide plate that guides the switchback conveyance from the second conveyance path to the fourth conveyance path. Therefore, the second gate member passes through the recording medium in the space between the first gate member and the guide plate that leads from the first conveyance path to the third conveyance path. By doing so, the recording medium is configured to function as a guide plate that guides the switchback conveyance from the second conveyance path to the fourth conveyance path, while the recording medium is placed in the space between the first gate member. By passing, the third transport from the first transport path Has a structure that functions as a guide plate that leads to,
The first gate member and the second gate member are linked by linkage means so that the posture changes in conjunction with each other,
A recording medium conveying mechanism, characterized in that a restricting member for restricting a change in the posture of the gate member is provided, and the posture of the gate member can be changed by the movement of the restricting member. The recording medium transport mechanism according to claim 1,
The first and second gate members are adapted to change their posture by rotating around a rotation axis.
The position where the rotation axis of the first gate member and the rotation axis of the second gate member are opposed to each other in a direction different from the extending direction of each conveyance path and sandwich the junction portion at the path end of each conveyance path A recording medium transport mechanism, wherein The recording medium transport mechanism according to claim 1 or 2 ,
The first gate member and the second gate member change their postures so as to close a conveyance path other than the two conveyance paths when conveying a recording medium from one conveyance path to another conveyance path. A recording medium conveyance mechanism characterized by comprising: In the recording medium conveyance mechanism according to any one of claims 1 to 3 ,
In the conveyance mode in which the recording medium is conveyed from the first conveyance path to the second conveyance path, an urging unit is provided that applies an urging force to the first gate member in the direction of closing the second conveyance path. A recording medium conveying mechanism characterized by comprising: The recording medium transport mechanism according to claim 4 , wherein
When the recording medium passes from the first conveying path toward the second conveying path, the recording medium pushes the first gate member against the urging force of the urging means and introduces it into the second conveying path. A recording medium transport mechanism having the structure described above. In the recording medium transport mechanism according to any one of claims 1 to 5 ,
The first and second gate members can change posture between the first posture and the second posture,
When each gate member is in the first posture, the recording medium can be conveyed from the first conveying path to the second conveying path, and the recording medium can be conveyed from the second conveying path to the fourth conveying path. A recording medium transport mechanism. The recording medium transport mechanism according to claim 6 ,
A recording medium transport mechanism, wherein the third transport path is closed when each gate member is in the first posture. In the recording medium transport mechanism according to any one of claims 1 to 7 ,
A drive mechanism for changing the posture of each gate member so as to transport the recording medium to the third transport path is provided in an accessory device. An image forming apparatus comprising the recording medium conveyance mechanism according to any one of claims 1 to 8 ,
An image forming unit that forms an image on the recording medium is provided, and the recording medium on which image formation has been performed in the image forming unit is moved in accordance with a change in posture of the first and second gate members. An image forming apparatus configured to be transported and discharged from one transport path among four transport paths to another transport path.

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