JP2007008676A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact image forming device capable of forming an image in one surface and the other surface of a paper sheet without reversing image data upside down. <P>SOLUTION: This image forming device is provided with a setting part 12 for selectively setting to form an image in one surface of the paper sheet 3, which is fed from a paper feeding part 2, to deliver it and setting to form an image in the other surface after forming the image in one surface to delivery it has a reversing device 6 for delivering the paper sheet 3, which is formed with the image by an image forming means, as it is when image formation in the only one surface is set and for conveying the paper sheet 3 in a direction crossing the paper sheet 3 conveying direction to reverse the paper sheet 3, while curving, after forming the image in one surface of the paper sheet with the image forming means when image formation in the other surface of the paper sheet 3 is set, and has a reverse conveying passage 7 for conveying the paper sheet 3, which is reversed and fed, to the image forming means again. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, an image forming unit that forms an image on one side of a sheet fed from a sheet feeding unit forms and discharges an image on one side of the sheet, and after an image is formed on one side of the sheet. An image forming unit that can selectively set whether to form an image on one side of the sheet or to form an image on both sides of the sheet is provided with a setting unit that selectively sets whether to form and discharge an image on the other side. It relates to the device.

  2. Description of the Related Art Many image forming apparatuses such as printers and copiers in recent years have adopted an apparatus that can select between forming an image on one side of a sheet and forming an image on both sides of the sheet. When an image is formed on both sides of a sheet in such an image forming apparatus, after the image is formed on one side by the image forming unit, the sheet is reversed and transported to the image forming unit again, and automatically on the other side. In this way, an image is formed.

  As such a conventional image forming apparatus, for example, there is an apparatus shown in Patent Document 1 below. The image forming unit includes a paper feeding unit, an image forming unit that forms a toner image on a paper conveyed from the paper feeding unit through a paper feeding conveyance path by an electrophotographic process, and a fixing unit that fixes the toner image on the paper. And a pair of paper discharge rollers for discharging the paper on which the image has been formed to a paper discharge tray. Further, in order to perform the double-sided printing function, an intermediate tray for temporarily placing a sheet on which an image is formed on one side and a sheet on which an image is formed on one side are disposed on the discharge roller side or the intermediate tray side. A branching claw for selectively guiding, a switchback means including a switchback roller for reversing the sheet conveyed to the intermediate tray, and a reversed sheet conveyance path or a reversed sheet feeding conveyance for the switched back sheet And a switching claw for selectively guiding to the road. For image formation on only one side of the paper, an image is formed by the image forming means on the paper conveyed from the paper feeding unit through the paper feeding conveyance path, and the paper on which the image is formed on one side by setting the branching claw is discharged. The paper is guided to the paper roller and discharged to the paper discharge tray. On the other hand, when images are formed on both sides of the paper, the paper on which the image is formed on one side by the image forming means is guided to the intermediate tray by the branching claw, and the paper switched back by the switchback means is reversed and conveyed by the switching claw. The image is guided to the road, conveyed to the image forming means again, and an image is formed on the other side, and an image is formed on the other side. Thereafter, the paper is guided to the paper discharge roller by the guide of the branching claw and discharged to the paper discharge tray.

JP 2000-16663 (paragraphs [0006], [0008] to [0010])

  However, in the above-described conventional technology, the sheet is reversed by the switchback unit when images are formed on both sides of the sheet. For this reason, when forming an image on one side and when forming an image on the other side corresponding to the back side, the top and bottom of the paper is inverted, so the image data must be inverted accordingly. . Therefore, the image forming apparatus has a problem in that the configuration is complicated because it requires special inversion processing of image data formed on the back surface of the paper.

  Further, since it is necessary to provide a transport path constituting the switchback means separately from the normal transport path, there is a problem that the image forming apparatus itself becomes large.

  Accordingly, an object of the present invention is to provide a small image forming apparatus that does not reverse the top of image data when forming an image on one side and the other side of a sheet.

In order to solve the above problem, an image forming apparatus according to claim 1 of the present application is characterized in that one side of the sheet is formed by an image forming unit that forms an image on one side of the sheet fed from a sheet feeding unit. An image forming apparatus comprising setting means for selectively setting an image to be discharged and forming an image on one surface and then forming and discharging an image on the other surface;
Provided on the downstream side of the image forming means, and when the setting means is set to form an image on only one side, the sheet on which the image is formed by the image forming means is sent as it is, and the setting means When the image forming unit is set to form an image on the other side of the sheet, the image forming unit forms an image on the one side and then conveys the sheet in a direction orthogonal to the sheet conveying direction. Reversing means for reversing and feeding the front and back while curving the paper;
A reversing transport unit that transports the paper that has been reversed and sent by the reversing unit to the image forming unit;
It is comprised from these.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the reversing unit includes:
A flat first transport path having an inlet and an outlet for the paper;
A second transport path having an outlet for the paper and arranged in parallel with the first space;
A semicircular arc-shaped passage that connects one side ends of the first and second transport paths;
A first transport mechanism provided in the first and second transport paths for transporting the paper in the exit direction;
A second transport mechanism that is provided in the first and second transport paths and transports the paper in a direction orthogonal to the transport direction of the first transport mechanism;
With
When the setting means is set so as not to reverse the paper, only the first transport mechanism is operated to send the paper to the exit of the first transport path, so that the paper is reversed. In this case, after the sheet is transported onto the second transport mechanism by the first transport mechanism, the second transport mechanism is operated, and the sheet is transported from the first transport path through the passage. The sheet is conveyed to the second conveyance path, and the sheet conveyed to the second conveyance path is sent out to the outlet of the second conveyance path by the first conveyance mechanism.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the other end portion of the first and second transport paths where the passage is not provided is closed, and the inversion is performed. Means
A shutter that is provided so as to be openable and closable near an exit of the first conveyance path and prevents conveyance of the paper;
First detecting means for detecting that the sheet is in contact with the shutter;
A second detection means for detecting that the sheet is in contact with the closed other end of the second transport path;
Further comprising
The first transport mechanism is controlled to stop driving by the output of the first detection means and start driving by the output of the second detection means,
The second transport mechanism is controlled to start driving by the output of the first detecting means and stop driving by the output of the second detecting means.

According to a fourth aspect of the present invention, in the image forming apparatus according to the second or third aspect, the first and second transport mechanisms are
At least one roller each formed from a charged material;
A motor for rotationally driving the roller;
A charging unit for charging the roller while rotating the roller;
A static elimination unit for neutralizing the roller charged by the charging unit in a state where the roller is stopped;
It is comprised from these.

In the image forming apparatus according to claim 5 of the present application, an image is formed on one side of the sheet by the image forming unit that forms an image on one side of the sheet fed from the sheet feeding unit, and is discharged. And an image forming apparatus provided with a setting unit that selectively sets an image to be formed and discharged on the other surface,
Reversing means for conveying the paper in a direction perpendicular to the conveying direction of the paper on which an image is formed by the image forming means, and reversing and sending the paper while curving the paper;
When the setting unit is set to form an image on only one side, the sheet on which the image is formed by the image forming unit is sent as it is, and the setting unit forms an image on the other side of the sheet. A selection unit that conveys the sheet on which the image is formed on the one surface by the image forming unit to the reversing unit when the setting to be performed is performed,
A reversing transport unit that transports the paper that has been reversed and sent by the reversing unit to the image forming unit;
It is comprised from these.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the reversing unit includes:
A flat first transport path having an inlet for the paper;
A second transport path having an outlet for the paper and arranged in parallel with the first space;
A semicircular arc-shaped passage that connects one side ends of the first and second transport paths;
A first transport mechanism provided in the first and second transport paths for transporting the paper in the exit direction;
A second transport mechanism that is provided in the first and second transport paths and transports the paper in a direction orthogonal to the transport direction of the first transport mechanism;
With
After transporting the paper onto the second transport mechanism by the first transport mechanism, the second transport mechanism is operated to transport the paper from the first transport path to the second transport path via the passage. The sheet conveyed to the second conveyance path is sent out to the outlet of the second conveyance path by the first conveyance mechanism.

According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the other end of the first and second transport paths where the passage is not provided, and the first transport path. The front end facing the inlet is closed and the reversing means is
First detection means for detecting that the sheet is in contact with the closed front end portion of the first transport path;
A second detection means for detecting that the sheet is in contact with the closed other end of the second transport path;
Further comprising
The first transport mechanism is controlled to stop driving by the output of the first detection means and start driving by the output of the second detection means,
The second transport mechanism is controlled to start driving by the output of the first detecting means and stop driving by the output of the second detecting means.

According to an eighth aspect of the present invention, in the image forming apparatus according to the sixth or seventh aspect, the first and second transport mechanisms are
At least one roller each formed from a charged material;
A motor for rotationally driving the roller;
A charging unit for charging the roller while rotating the roller;
A static elimination unit for neutralizing the roller charged by the charging unit in a state where the roller is stopped;
It is comprised from these.

  The present invention has the following excellent effects by having the above-described configuration. That is, in the image forming apparatus according to claim 1 of the present application, when the setting unit sets image formation on one side, that is, only one side, after the image is formed on one side by the image forming unit, It is discharged as it is. When setting the image formation on both sides, the paper is conveyed while curving in the direction perpendicular to the conveyance direction when the image is formed by the reversing unit after the image is formed on only one side. After that, the reversed paper is conveyed again to the image forming means by the reversing conveying means, and is discharged after an image is formed on the other surface. As described above, since the image is rotated and reversed in the direction orthogonal to the transport direction, the upper part of the sheet when the image is formed on the other side is supplied to the image forming unit in a state where it coincides with the upper side of the one side. Therefore, it is not necessary to invert the data itself when forming image data on the other surface. Accordingly, it is not necessary for the image forming apparatus to invert the image data in order to form an image on both sides. Further, since the reversing means curves and inverts the paper, it can be formed compactly, so that the apparatus itself can be miniaturized.

  In the image forming apparatus according to claim 2 of the present application, when the sheet is not reversed, the first conveyance path is directly passed by the first conveyance mechanism, but when the sheet is reversed, the first conveyance path is used. The paper is transported by the first transport mechanism until the paper is positioned on the second transport mechanism, and then transported in the direction perpendicular to the transport direction of the first transport mechanism by the second transport mechanism, and the paper is curved. It conveys until it contacts the side wall of the second conveyance path. In addition, when the conveyance is completed, the first conveyance mechanism is used to convey in the exit direction. Therefore, the selection operation between the case where the sheet is not reversed and the case where the sheet is reversed can be reliably performed, and the configuration is simple and can be realized at low cost.

  In the image forming apparatus according to claim 3 of the present application, a shutter is provided at the exit portion of the first conveyance path, and the sheet conveyance position can be accurately adjusted by the shutter, and the sheet conveyed by the detection unit can be adjusted. By accurately recognizing the position and controlling the first and second transport mechanisms in accordance with the output of the detection means, it becomes possible to transport the paper more accurately.

  In the image forming apparatus according to claim 4 of the present application, one or a plurality of rollers are made of a charging material, and only the driving roller is charged, whereby static electricity is generated in the roller, whereby the sheet is transferred to the roller. Since it is adsorbed and conveyed, it can be reliably conveyed. Further, since the rollers that are not driven are neutralized by the neutralization unit, it is possible to smoothly convey the sheet without causing any trouble in the conveyance of the transition.

  In the image forming apparatus according to claim 5 of the present application, when the setting unit sets image formation on one side, that is, only one side, after the image is formed on one side of the sheet by the image forming unit, the selecting unit Sorts out the paper as it is. In setting the image formation on both sides, after the image is formed on one side, the sorting unit sorts the sheet so that the sheet is conveyed in the direction in which the reversing unit is provided. The sheet conveyed to the reversing unit is conveyed while curving the sheet in a direction orthogonal to the conveying direction when the image is formed by the image forming unit to reverse the front and back, and the sheet is conveyed by the reversing conveying unit. It is conveyed again to the image forming means, and an image is formed on the other surface and discharged. As described above, since the image is rotated and reversed in the direction orthogonal to the transport direction, the upper part of the sheet when the image is formed on the other side is supplied to the image forming unit in a state where it coincides with the upper side of the one side. Therefore, it is not necessary to invert the data itself when forming image data on the other surface. Accordingly, it is not necessary for the image forming apparatus to invert the image data in order to form an image on both sides. Further, since the reversing means curves and inverts the paper, it can be formed compactly, so that the apparatus itself can be miniaturized. In addition, since the sorting unit reliably sorts the sheet discharge path according to the setting of the single-sided image formation or the double-sided image formation by the setting unit, accurate single-sided and double-sided image formation can be achieved.

  In addition, in the image forming apparatus according to claims 6 to 8 of the present application, in addition to the effect of claim 5, it is possible to provide an image forming apparatus that exhibits the effect of claims 2 to 4.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. However, the embodiments described below exemplify an image forming apparatus for embodying the technical idea of the present invention, and are not intended to specify the present invention, and are not intended to limit the scope of the claims. Other embodiments included in are equally applicable.

  Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is an explanatory diagram illustrating an internal structure of an image forming apparatus according to a first embodiment of the present invention, FIG. 2 is a perspective view illustrating a reversing device in FIG. 1, and FIG. 3 is a perspective view illustrating a drive unit of the reversing device in FIG. 4 is a block diagram showing a control system of the image forming apparatus, and FIG. 5 is a perspective view showing an inner surface of a cover of the reversing device in FIG.

  In FIG. 1, an image forming apparatus 1 includes a paper feeding unit 2, a transfer unit 4 that transfers image data that has already been acquired to a paper 3 that is fed from the paper feeding unit 2, and image data that has been transferred to the paper 3. The fixing unit 5 for fixing, the reversing device 6 for selectively reversing the front and back of the paper 3 on the downstream side of the fixing unit 5, and the reversing conveyance path for conveying the paper 3 reversed by the reversing device 6 to the transfer unit 4 again. 7 and a paper discharge tray 8 for storing the paper 3 on which an image is formed and discharged.

  The transfer unit 4 includes a photosensitive drum 41 that rotates at a constant speed in a certain direction to form image data obtained from an original by an electrophotographic process as a toner image, and a conveyance path 10 that will be described later. The transfer device 42 is arranged opposite to each other, and the toner image is transferred by the transfer device 42 to one side of the sheet 3 sent to the photosensitive drum 41. Further, a charging device 43 for uniformly charging the surface of the photoconductive drum 41 is provided on the peripheral surface of the photoconductive drum 41, and a laser is applied to the surface of the photoconductive drum 41 after the charging process to electrostatic latent image. A writing device 44 for writing an image, a developing device 45 for developing the toner by attaching the toner to the surface of the photosensitive drum 41 on which the electrostatic latent image is written, and removing the toner remaining on the surface of the photosensitive drum 41 after the transfer. And a cleaning device 46 for recovery.

  The fixing unit 5 includes a heating roller 51 and a pressure roller 52 that presses the paper 3 on which the toner image is formed on the heating roller 51. The heating roller 51 and the pressure roller 52 rotate so as to transfer the paper 3 from the transfer unit 4 to the reversing device 6.

  Between the transfer unit 4 and the fixing unit 5, a transfer conveyance belt 9 for conveying the paper 3 from the transfer unit 4 to the fixing unit 5 is provided. The transfer unit 4, the fixing unit 5, and the transfer conveyance are provided. Image forming means for forming an image on one side of the paper 3 is formed by the belt 9.

  Between the paper feeding unit 2 and the transfer unit 4, a conveyance path 10 including a plurality of rollers for conveying the paper 3 from the paper feeding unit 2 to the transfer unit 4 is provided. Further, a discharge roller 11 is provided between the reversing device 6 and the paper discharge tray 8 to discharge the paper 3 that has come out of the reversing device 6 to the paper discharge tray 8.

  The reversing device 6 sends the paper 3 to the discharge roller 11 without reversing and sends the paper 3 to the reversing conveyance path 7 according to the setting of single-sided printing / double-sided printing set in the setting unit 12. Are selectively performed, and the setting operation of the setting unit 12 is performed by operating an operation panel (not shown).

A specific configuration of the reversing device will be described below with reference to FIGS.
As shown in FIG. 2, the reversing device 6 includes a case 61 formed of a flat cylindrical body in which a through hole having a lateral width longer than the lateral width of the sheet 3 conveyed through the conveyance path 10 is formed. A partition plate 65 connected to one side surface of the through hole and extending to a position close to the other side surface facing the one side surface so as to bisect the through hole of the case 61 in the vertical direction, The other side end of the case 61 is curved in an arc shape, and the through hole of the case 61 has a substantially U-shaped cross section.

  The substantially U-shaped through hole has a first space 62 and a second space 63 at the upper and lower portions of the through hole divided into two by the partition plate 65, and connects one end portions of the first and second spaces 62 and 63. And a curved passage 66. In the first space 62, the direction indicated by the arrow A constitutes the inlet of the sheet 3, and the direction indicated by the arrow B constitutes one outlet thereof. In the second space 63, the direction indicated by the arrow C constitutes another outlet of the paper 3. A shutter 67 is provided at the exit of the first space 62 to selectively prevent the paper 3 from being ejected from the direction of arrow B.

  As shown in FIG. 3, a first transport mechanism 68X that transports the paper 3 in the X-axis direction corresponding to the directions of arrows B and C shown in FIG. This X-axis direction is the same as the direction in which the image is transferred by the transfer unit 4. Further, a second transport mechanism 68Y that transports the paper 3 in the Y-axis direction orthogonal to the X-axis is also provided on the surface on which the first transport mechanism 68X is provided. Here, the first transport mechanism 68X is provided with a plurality of first rollers 69X that rotate in the X-axis direction, and the second transport mechanism 68Y is a plurality of second rollers 69Y that rotate in the Y-axis direction. Is provided.

  A setting unit 12 is connected to the inverting device 6, and the setting unit 12 includes a control circuit 13 and an operation unit 14 as shown in FIG. The first roller 69X and the second roller 69Y are independently connected to the first motor 70X and the second motor 70Y, respectively, and the first motor 70X and the second motor 70Y are control circuits. 13 are connected to the output side. Further, the control circuit 13 includes a first detector 71 that detects that the sheet 3 has completely entered the first space 62 and the leading end of the sheet 3 has contacted the shutter 67 in the first space 62, and the sheet There is provided a second detector 72 for detecting that 3 has entered the second space 63 and the side end has come into contact with the side wall of the second space 63. Further, a shutter drive unit 73 including a plunger solenoid that opens and closes the shutter 67 is connected to the control circuit 13. When the control circuit 13 detects that double-sided printing has been selected in the operation unit 14, the shutter driving unit 73 operates the shutter 67 to close the outlet (arrow B) of the first space 62. . At this time, the control circuit 13 detects by the first detector 71 that the sheet 3 sent by the first roller 69X has entered the first space 62 and has come into contact with the shutter 67, and the first motor Control is performed so that the operation of 70X is stopped and the second motor 70Y is operated. The sheet 3 is transferred from the first space 62 to the second space 63 through the passage 66 by the rotation of the second roller 69Y by the operation of the second motor 70Y.

  When the sheet 3 transferred into the second space 63 by the second roller 69Y enters the second space 63 and its side edge comes into contact with the second detector 72, the second detector 72 is reached. The control circuit 13 stops the operation of the second motor 70Y and controls the first motor 70X to operate according to the detected output.

  The first roller 69X and the second roller 69Y are made of a chargeable material. The output side of the control circuit 13 is connected with a first charging unit 74X that charges the first roller 69X when the paper 3 is transferred in the X-axis direction, and when the paper 3 is transferred in the Y-axis direction. The second charging unit 74Y for charging the second roller 69Y is connected to the second charging unit 74Y. The output side of the control circuit 13 is connected to a first static elimination unit 75X that removes the charge of the first roller 69X when the transfer of the paper 3 in the X-axis direction is completed, and is connected to the second roller 69Y. Similarly, the second static elimination unit 75Y is connected.

  On the upper surface of the first space 62 and the lower surface of the second space 63, as shown in FIG. 5, a plurality of balls 76 that are rotatable over the entire surface are provided. The ball 76 freely rotates in the X-axis direction and the Y-axis direction, and is provided to reduce the frictional force generated in the paper 3 moving in the first and second spaces 62 and 63. It is.

Next, a series of image forming steps of the image forming apparatus 1 in the configuration of the first embodiment described above will be described.
When single-sided printing is selected by the operation unit 14, the setting unit 12 instructs to form an image on only one side. At this time, the image data acquired from the client PC connected to the image forming apparatus 1 or by the scanner unit provided in the main body of the image forming apparatus 1 is written on the charged surface of the photosensitive drum 41 by the writing device 44. . The written latent image is attached with toner by the developing device 45, and the toner image is transferred from the paper feeding unit 2 to the paper 3 fed to the photosensitive drum 41 and fixed by the fixing unit 5. The sheet 3 on which an image is formed on one side by such image forming means is sent to the reversing device 6. At this time, the sheet 3 enters the first space 62 from the direction of the arrow A, is transported in the X-axis direction by the first transport mechanism 68X, and similarly travels toward the exit of the first space 62. At this time, since the shutter 67 at the exit of the first space 62 is open, the sheet 3 is sent in the direction indicated by the arrow B from the exit. Then, the paper is discharged to the paper discharge tray 8 by the discharge roller 11.

  When double-sided printing is selected by the operation unit 14, the setting unit 12 issues an instruction to form a double-sided image. At this time, the image data acquired by the image forming apparatus 1 is written on the charged surface of the photosensitive drum 41 by the writing device 44. The written latent image is attached with toner by the developing device 45, and the toner image is transferred from the paper feeding unit 2 to the paper 3 fed to the photosensitive drum 41 and fixed by the fixing unit 5. The sheet 3 on which an image is formed on one side by such image forming means is sent to the reversing device 6. At this time, the sheet 3 enters the first space 62 from the direction of the arrow A, is transported in the X-axis direction by the first transport mechanism 68X, and similarly travels toward the exit of the first space 62. However, since double-sided printing is selected in the operation unit 14, the shutter 67 provided near the exit of the first space 62 is closed by the shutter driving unit 73, and the first space 62 has a closed state. The sheet 3 conveyed is in contact with the shutter 67. When the sheet contacts the shutter 67, the first detector 71 detects this contact, and the control circuit 13 stops the operation of the first transport mechanism 68X by the detection output of the first detector 71, and the first detector 71 detects the contact. The operation of the second transport mechanism 68Y is started.

  Specifically, in the first transport mechanism 68X, the first roller 69X is rotated by the first motor 70X and charged by the first charging unit 74X. Therefore, when the first roller 69X is in the operating state, the sheet 3 is transported while being attracted to the roller 69X by static electricity. However, the operation state of the first transport mechanism 68X is stopped and the second roller 69X is stopped. When the transport mechanism 68Y is actuated, the control circuit 13 stops the operation of the first motor 70X, and at the same time, the first neutralization unit 75X neutralizes the charged state of the first roller 69X. Then, the control circuit 13 activates the second motor 70Y and simultaneously charges the second roller 69Y with the second charging unit 74Y. For this reason, the sheet 3 is transferred while being changed in direction from the transfer in the X-axis direction to the Y-axis direction. At this time, since the sheet 3 is transported while being attracted to the first roller 69X and attracted to the second roller 69Y, the transport direction is stably changed. Then, the sheet 3 passes through the passage 66 while being curved along the curved shape, and is conveyed into the second space 63.

  When the sheet 3 completely enters the second space 63, the second detector 72 detects this, and the control circuit 13 stops the operation of the second transport mechanism 68Y by the detection output of the second detector 72, and The operation of the first transport mechanism 68X is started. Accordingly, the sheet 3 is sent out from the reversing device 6 by the first transport mechanism 68X. The sheet 3 sent out from the reversing device 6 is discharged from the second space 63 as indicated by an arrow C in a state where the front and back sides are reversed. The reversed sheet 3 is conveyed again by the reversing conveyance path 7 to the transfer unit 4 constituting the image forming unit. The transfer unit 4 transfers the image data obtained from the document to a surface different from the surface on which the previous printing was performed on the paper 3. Similarly, the image is fixed by the fixing unit 5 and sent to the reversing device 6.

  When the sheet 3 having the image data printed on both sides thereof is conveyed into the reversing device 6, the reversing device 6 has the first conveying mechanism 68 </ b> X activated by the control circuit 13 and the shutter 67 opened. Therefore, the sheet 3 on which the image is formed on one side and the other side, that is, both sides passes through the first space 62 as it is and is discharged to the discharge tray 8 by the discharge roller 11.

  As described above, in the image forming apparatus 1 according to the first embodiment of the present invention, when the setting unit 12 sets image formation on only one side of the paper 3, the transfer unit 4 constituting the image forming unit, The sheet 3 having an image formed on one side by the fixing unit 5 or the like is discharged as it is. When image formation is set on both sides of the sheet 3, the sheet 3 is aligned in the Y-axis direction perpendicular to the X-axis in the conveying direction when the image is formed by the reversing device 6 after the image is formed on one side. Invert the front and back by conveying while curving. Thereafter, the reversed sheet 3 is conveyed again to the transfer unit 4 and the fixing unit 5 through the reversing conveyance path 7, and an image is formed on the other side and discharged. For this reason, the top of the sheet 3 when the image is formed on the other side is supplied to the image forming unit in alignment with the top of the one side, so it is necessary to invert the top of the image data formed on the other side. There is no.

  That is, the reversing device 6 passes the first space 62 as it is by the first transport mechanism 68X when the paper 3 is not reversed, but when the paper 3 is reversed, the reversing device 6 exits the first space 62. Is closed by the shutter 67, and when the first detector 71 detects that the sheet 3 has completely entered the first space 62, the second transport mechanism 68Y transports it in the Y-axis direction orthogonal to the X-axis, When the sheet 3 is conveyed along the arcuately curved path 66 until it abuts against the side wall of the second space 63 and the abutment is detected by the second detector 72, The first transport mechanism 68X provided on the back surface is transported in the exit direction. Therefore, since the first space 62 and the second space 63 are flat and can be arranged in parallel, the reversing device 6 has a compact shape.

  The first roller 69X and the second roller 69Y are independently rotated by the first motor 70X and the second motor 70Y, respectively, and when rotated, the first charging unit 74X and the second roller 69X are respectively independently rotated. When the rotation is stopped by the charging unit 74Y, the charge is removed by the first charge removing unit 75X and the second charge removing unit 75Y independently. Therefore, the sheet 3 transported in the reversing device 6 can be reliably transported by being attracted to the rotating first roller 69X or the second roller 69Y, and charged and charged in accordance with the driving of the roller. Since static elimination is performed, the transfer direction can be changed smoothly. Although the motors for driving the first and second rollers 69X and 69Y are provided independently, the first and second rollers 69X and 69Y are not driven at the same time, so only one motor is used. The same effect can be obtained even if the driving force of the motor is switched and transmitted.

  Next, an image forming apparatus 1 ′ according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is an explanatory diagram of the image forming apparatus according to the second embodiment of the present invention, and FIG. 7 is a block diagram showing a control system of the image forming apparatus according to the second embodiment of the present invention. However, in the image forming apparatus 1 ′ according to the present embodiment, the same parts as those of the image forming apparatus 1 according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the image forming apparatus 1 ′ according to the present embodiment, a sorting piece 80 is provided on the downstream side of the fixing unit 5 constituting the image forming unit. A reversing device 81 for reversing the front and back of the sheet 3 is disposed on the reversing conveyance path 7. The sorting piece 80 is configured to send the paper 3 sent from the fixing unit 5 to the discharge roller 11 and the reversing device 81 in accordance with the setting state of the setting unit 12. That is, when it is received from the setting unit 12 that single-sided printing has been selected, the sorting piece 80 is rotated so as to guide the sheet 3 fed from the fixing unit 5 to the discharge roller 11 side, and double-sided printing is performed from the setting unit 12. When the selection is received, the sorting piece 80 is rotated so as to guide the sheet 3 on which the image is formed on one surface sent out from the fixing unit 5 to the reversing conveyance path 7 side. Even when double-sided printing is selected, when the sheet 3 on which images are already formed is sent out from the fixing unit 5, it is sent out to the discharge roller 11 side.

  Since the reversing device 81 is different from the reversing device 6 in the first embodiment only in that the reversing device 81 does not have an outlet in the first space 62, the drawing thereof is omitted. As shown in FIG. 7, a sorting piece driving unit 82 that drives the sorting piece 80 is connected to the output side.

Next, a series of image forming steps of the image forming apparatus 1 ′ in the configuration of the above-described second embodiment will be described.
When single-sided printing is selected by the operation unit 14, the setting unit 12 instructs to form an image on only one side. At this time, the image data acquired from the client PC connected to the image forming apparatus 1 ′ or by the scanner unit provided in the main body of the image forming apparatus 1 ′ is applied to the charged surface of the photosensitive drum 41 by the writing device 44. Written. The written latent image is attached with toner by the developing device 45, and the toner image is transferred from the paper feeding unit 2 to the paper 3 fed to the photosensitive drum 41 and fixed by the fixing unit 5. The sheet 3 on which an image is formed on one side by such an image forming unit is guided to the discharge roller 11 side by the sorting piece 80 and discharged to the discharge tray 8.

  When double-sided printing is selected by the operation unit 14, the setting unit 12 issues an instruction to form a double-sided image. At this time, the image data acquired by the image forming apparatus 1 ′ is written on the charged surface of the photosensitive drum 41 by the writing device 44. The written latent image is attached with toner by the developing device 45, and the toner image is transferred from the paper feeding unit 2 to the paper 3 fed to the photosensitive drum 41 and fixed by the fixing unit 5. The sheet 3 on which an image is formed on one side by such image forming means is guided to the reversing conveyance path 7 side by the sorting piece 80, and is sent to the reversing device 81 through the reversing conveyance path 7.

  The sheet 3 enters the first space 62 from the direction of arrow A as in the first embodiment. However, in this embodiment, the portion corresponding to the outlet of the first space 62 is closed, and the sheet 3 is conveyed in the X-axis direction by the first conveying mechanism 68X, and the first detector 71 is output. Then, the control circuit 13 stops the operation of the first transport mechanism 68X by the detection output of the first detector 71 and starts the operation of the second transport mechanism 68Y. Since the driving of the first and second transport mechanisms 68X and 68Y is the same as the reversing process shown in the first embodiment, the description thereof is omitted.

  An image is formed again on the reverse side of the sheet 3 reversed by the above-described process, but the image is already formed on the front and back surfaces of the sorting piece 80 by driving the sorting piece driving unit 82 by the control circuit 13. The sheet 3 sent out from the fixing unit 5 is sent out in the direction of the discharge roller 11.

  Therefore, in the image forming apparatus 1 ′ according to the second embodiment of the present invention, when the setting unit 12 sets image formation on one side of the sheet 3, that is, only one side, the transfer unit 4 constituting the image forming unit, The sheet 3 having an image formed on one side is selected by the fixing unit 5 so as to be sent out as it is to the paper discharge tray 8 by the selection piece 80. In setting the image formation on both sides of the sheet 3, first, the sheet 3 having an image formed on one side is sent by the sorting piece 80 in the direction of the reversing conveyance path 7. Then, the sheet 3 is conveyed while being curved in the Y-axis direction orthogonal to the X-axis of the conveying direction when an image is formed by the reversing device 81 to reverse the front and back, and the reversed sheet 3 is conveyed to the reversing conveyance path 7. Accordingly, the sheet is conveyed again to the transfer unit 4 and the fixing unit 5, and an image is formed on the other surface and is discharged to the paper discharge tray 8. For this reason, the top of the sheet 3 when the image is formed on the other side is supplied to the image forming unit in alignment with the top of the one side, so it is necessary to invert the top of the image data formed on the other side. There is no.

  Whether the sheet 3 is discharged as it is or sent to the reversing device 81 can be achieved by simple control by simply changing the rotation position of the sorting piece 80.

  Further, when the paper 3 is not reversed, the paper 3 is ejected as it is to the paper ejection tray 8, but when the paper 3 is reversed, the paper 3 having an image formed on one side thereof is sorted by the sorting piece 80 toward the reversing device 81. To send to. The first detector 71 detects that the sheet 3 has completely entered the first space 62 of the reversing device 81, and the sheet is conveyed in the Y-axis direction perpendicular to the second conveying mechanism 68Y, and the sheet is bent to the second position. The second detector 72 detects that the contact has been made, and transports it in the exit direction by the first transport mechanism 68X. Therefore, since the first space 62 and the second space 63 are flat and can be arranged in parallel, the reversing device 81 has a compact shape.

  In the first and second embodiments of the present invention described above, the first transport mechanism 68X and the second transport mechanism 68Y charge the first roller 69X and the second roller 69Y to make the sheet 3 Was sucked and transported. However, the present invention can be variously modified, for example, the air flow may be generated without charging and the sheet 3 may be reliably conveyed.

  In the first and second embodiments of the present invention described above, the first roller 69X and the second roller 69Y are used for the first transport mechanism 68X and the second transport mechanism 68Y. The invention is not limited to this, and various transport mechanisms such as a belt can be used.

  In the first and second embodiments of the present invention described above, the positions of the first roller 69X and the second roller 69Y used in the first transport mechanism 68X and the second transport mechanism 68Y are changed. However, the first roller 69X and the second roller 69Y are movable in the vertical direction, and are displaced so as to protrude in the direction in which the paper 3 is positioned when being transported, so that the paper 3 is reliably contacted. Thus, the conveyance can be performed satisfactorily.

FIG. 1 is an explanatory diagram showing the internal structure of the image forming apparatus in Embodiment 1 of the present invention. FIG. 2 is a perspective view showing the reversing device in FIG. FIG. 3 is a perspective view showing a drive unit of the reversing device in FIG. FIG. 4 is a block diagram showing the internal configuration of the control unit of the image forming apparatus in FIG. FIG. 5 is a perspective view showing the inner surface of the cover of the reversing device in FIG. FIG. 6 is an explanatory view showing the internal structure of the image forming apparatus in Embodiment 2 of the present invention. FIG. 7 is a block diagram showing the internal configuration of the control unit of the image forming apparatus in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper supply part 3 Paper 4 Transfer part 5 Fixing part 6 Inversion apparatus 7 Reverse conveyance path 8 Paper discharge tray 9 Conveyance belt 10 Conveyance path 11 Discharge roller 12 Setting part 13 Control circuit 41 Photosensitive drum 42 Transfer device 44 writing device 45 developing device 51 heating roller 52 pressure roller 61 case 62 first space 63 second space 64 one edge 65 partition plate 66 passage 67 shutter 68X first transport mechanism 68Y second transport mechanism 69X first Roller 69Y second roller 70X first motor 70Y second motor 71 first detector 72 second detector 73 shutter drive unit 74X first charging unit 74Y second charging unit 75X first charge removal Part 75Y second charge eliminating part 76 ball 80 sorting piece 81 reversing device 82 sorting piece drive part

Claims (8)

The image forming means for forming an image on one side of the paper fed from the paper feed unit forms and discharges an image on one side of the paper, and after the image is formed on one side, the other side In addition, in the image forming apparatus provided with setting means for selectively setting the image forming and discharging,
Provided on the downstream side of the image forming means, and when the setting means is set to form an image on only one side, the sheet on which the image is formed by the image forming means is sent as it is, and the setting means When the image forming unit is set to form an image on the other side of the sheet, the image forming unit forms an image on the one side and then conveys the sheet in a direction orthogonal to the sheet conveying direction. Reversing means for reversing and feeding the front and back while curving the paper;
A reversing transport unit that transports the paper that has been reversed and sent by the reversing unit to the image forming unit;
An image forming apparatus comprising: The inversion means is
A flat first transport path having an inlet and an outlet for the paper;
A second transport path having an outlet for the paper and arranged in parallel with the first space;
A semicircular arc-shaped passage that connects one side ends of the first and second transport paths;
A first transport mechanism provided in the first and second transport paths for transporting the paper in the exit direction;
A second transport mechanism that is provided in the first and second transport paths and transports the paper in a direction orthogonal to the transport direction of the first transport mechanism;
With
When the setting means is set so as not to reverse the paper, only the first transport mechanism is operated to send the paper to the exit of the first transport path, so that the paper is reversed. In this case, after the sheet is transported onto the second transport mechanism by the first transport mechanism, the second transport mechanism is operated, and the sheet is transported from the first transport path through the passage. 2. The image forming apparatus according to claim 1, wherein the sheet is conveyed to a second conveyance path, and the sheet conveyed to the second conveyance path is sent out to an outlet of the second conveyance path by the first conveyance mechanism. The other end of the first and second transport paths where the passage is not provided is closed, and the reversing means is
A shutter that is provided so as to be openable and closable near an exit of the first conveyance path and prevents conveyance of the paper;
First detecting means for detecting that the sheet is in contact with the shutter;
A second detection means for detecting that the sheet is in contact with the closed other end of the second transport path;
Further comprising
The first transport mechanism is controlled to stop driving by the output of the first detection means and start driving by the output of the second detection means,
The said 2nd conveyance mechanism is controlled so that the drive may be started by the output of the said 1st detection means, and the drive may be stopped by the output of the said 2nd detection means. The image forming apparatus described. The first and second transport mechanisms are
At least one roller each formed from a charged material;
A motor for rotationally driving the roller;
A charging unit for charging the roller while rotating the roller;
A static elimination unit for neutralizing the roller charged by the charging unit in a state where the roller is stopped;
The image forming apparatus according to claim 2, wherein the image forming apparatus comprises: The image forming means for forming an image on one side of the paper fed from the paper feed unit forms and discharges an image on one side of the paper, and forms and discharges an image on the other side. In an image forming apparatus provided with setting means for selectively setting the
Reversing means for conveying the paper in a direction perpendicular to the conveying direction of the paper on which an image is formed by the image forming means, and reversing and sending the paper while curving the paper;
When the setting unit is set to form an image on only one side, the sheet on which the image is formed by the image forming unit is sent as it is, and the setting unit forms an image on the other side of the sheet. A selection unit that conveys the sheet on which the image is formed on the one surface by the image forming unit to the reversing unit when the setting to be performed is performed,
A reversing transport unit that transports the paper that has been reversed and sent by the reversing unit to the image forming unit;
An image forming apparatus comprising: The inversion means is
A flat first transport path having an inlet for the paper;
A second transport path having an outlet for the paper and arranged in parallel with the first space;
A semicircular arc-shaped passage that connects one side ends of the first and second transport paths;
A first transport mechanism provided in the first and second transport paths for transporting the paper in the exit direction;
A second transport mechanism that is provided in the first and second transport paths and transports the paper in a direction orthogonal to the transport direction of the first transport mechanism;
With
After transporting the paper onto the second transport mechanism by the first transport mechanism, the second transport mechanism is operated to transport the paper from the first transport path to the second transport path via the passage. The image forming apparatus according to claim 5, wherein the sheet transported to the second transport path is sent to an outlet of the second transport path by the first transport mechanism. The other side end of the first and second transport paths where the passage is not provided and the front end facing the inlet of the first transport path are closed, and the reversing means is
First detection means for detecting that the sheet is in contact with the closed front end portion of the first transport path;
A second detection means for detecting that the sheet is in contact with the closed other end of the second transport path;
Further comprising
The first transport mechanism is controlled to stop driving by the output of the first detection means and start driving by the output of the second detection means,
The said 2nd conveyance mechanism is controlled so that the drive may be started by the output of the said 1st detection means, and the drive may be stopped by the output of the said 2nd detection means. The image forming apparatus described. The first and second transport mechanisms are
At least one roller each formed from a charged material;
A motor for rotationally driving the roller;
A charging unit for charging the roller while rotating the roller;
A static elimination unit for neutralizing the roller charged by the charging unit in a state where the roller is stopped;
The image forming apparatus according to claim 6, wherein the image forming apparatus comprises:

Images