JP2006137582A - Image forming device body and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To meet the demands of both a user who gives a priority to high double-sided image forming speed over a device installation area and a user who gives a priority to small device installation area over the double-sided image forming speed. <P>SOLUTION: This image forming device body is connectable to a stapler 2 having a pair of inverting rollers 21 for inverting the front face and rear face of paper, and comprises an image forming means, a pair of discharge rollers 86 for inverting the front face and rear face of the paper, a discharge port 11 for discharging the paper having an image formed on one side thereof to the stapler 2, and an accepting port 12 for accepting the paper inverted upside down by the pair of inverting rollers 21 from the stapler 2. When the stapler 2 is not connected, the front face and rear face of the paper are inverted by using the pair of discharge rollers 86, and when the stapler 2 is connected, the front face and rear face of the paper are inverted by using the pair of inverting rollers 21 to form images on both sides of the paper. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus main body capable of forming images on both sides of a sheet, and an image forming apparatus formed by connecting a post-processing device to the image forming apparatus main body.

  In recent years, from the viewpoint of reducing the occupation area of an image forming apparatus in the workplace or home, a so-called in-cylinder discharge type apparatus in which the sheet conveyance direction is set to the vertical direction and the sheet discharge unit is provided at the center in the vertical direction of the apparatus has been widely used. It's getting on. In FIG. 5, the schematic block diagram of this in-cylinder discharge type | mold apparatus is shown. In the image forming apparatus of this figure, a paper discharge space 3 having an opening on the front side is formed at a substantially central portion in the vertical direction of the apparatus main body 1. On the bottom surface of the paper discharge space 3, a tray 80 for placing paper to be discharged is formed integrally with the casing. On the other hand, a reading mechanism 91 for reading a document is built in the upper side of the paper discharge space 3, and an image forming mechanism (image forming means) is built in the lower side of the paper discharge space 3.

  The image forming mechanism of the apparatus main body will be described. The surface of the photosensitive drum 70 is uniformly charged positively or negatively by the charging device 71. On the other hand, a document (not shown) is placed on the document placing table 90, and the image data is read by the reading device 91. The read image data is written on the surface of the photosensitive drum 70 by a laser scanner (exposure device) 72, and an electrostatic latent image is formed on the surface of the photosensitive drum 70. Specifically, in the case of the reverse development method, the charge corresponding to the image is removed, and in the case of the regular development method, the charge corresponding to the background is removed to form an electrostatic latent image. Next, the electrostatic latent image on the photosensitive drum 70 is visualized with toner by the developing device 73. At this time, the charging polarity of the toner is the same as the charging polarity of the photosensitive drum 70 in the case of the reversal development method, and is opposite to the charging polarity of the photosensitive drum 70 in the case of regular development.

  On the other hand, the paper P stored in the paper feed cassette 81 is pulled out by the pickup roller 82, sandwiched between the paper feed roller 83 and the separating roller 84, and sent to the conveyance path. Then, the registration roller pair 51 feeds the paper P to the transfer unit at the timing when the toner image on the photosensitive drum 70 reaches the transfer unit. In the transfer portion, the sheet P is sandwiched between the photosensitive drum 70 and the transfer roller 74, and a charge having a polarity opposite to the toner charging polarity is applied to the transfer roller 74. Toner image moves onto the paper P. The toner remaining on the photosensitive drum 70 without moving onto the paper P is removed and collected by the cleaning roller 75. On the other hand, the paper P on which the toner image is placed is conveyed to the fixing roller pair 85. Here, the toner image is heated and pressurized by the fixing roller pair 85 and fixed on the paper P. Then, the paper P is sent to the paper discharge roller pair 86 by the branching claw 61.

  When image formation is performed only on one side of the sheet, the sheet is discharged to the tray 80 by the discharge roller pair 86 as it is. On the other hand, when forming images on both sides of the paper, the paper discharge roller pair 86 rotates in the reverse direction when the rear end of the paper is held between the paper discharge roller pair 86, and the paper is conveyed by the branching claw 61. It is sent in the direction of the roller 87 (so-called switchback). Then, the sheet is guided to the circulation conveyance path 50 by the branching claw 62 and is sent again to the registration roller pair 51 by the conveyance rollers 88 and 89. In the same manner as described above, after an image is formed on the other side surface of the paper, the paper P is sent to the paper discharge roller pair 86 by the branching claw 61 and discharged to the tray 80.

  In such an image forming apparatus, the pair of paper discharge rollers 86 is used as a mechanism for discharging the paper to the tray and also as a switchback mechanism. Therefore, the next paper must be kept waiting while the paper is switched back. In other words, the image forming speed when an image is formed on both sides of the sheet is reduced to about 70 to 83% of the case where an image is formed on one side of the sheet.

Accordingly, a technique has been proposed in which a switchback mechanism is provided in an accessory device outside the apparatus main body to increase the image forming speed when images are formed on both sides of a sheet (for example, Patent Document 1 and Patent Document 2).
JP-A-7-261471 (Claims, FIG. 1) JP 2003-182906 A (Claims, FIGS. 1 and 2)

  However, in the proposed technique, if the accessory device is not attached to the apparatus main body, images cannot be formed on both sides of the sheet, and a large installation area is required to place the apparatus main body and the accessory device side by side. In this case, since the double-sided image forming speed may be slow, the result is not in line with the user's desire for a device having a small installation area.

  SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems. The object of the present invention is to provide a user who prioritizes a high-speed double-sided image forming speed over the apparatus installation area and a double-sided image forming speed. An object of the present invention is to provide an image forming apparatus capable of meeting the demands of both users who give priority to a small installation area.

  The present inventor has provided a switchback mechanism for reversing the front and back of a sheet in order to prevent page misalignment caused by discharging the sheet with the image forming surface facing upward in a stapler or stacker conventionally used as a post-processing device. Focusing on the fact that it is mounted, the present inventors have come up with the idea that the image forming speed can be increased by using this switchback mechanism of the post-processing apparatus when performing double-sided image formation.

  That is, the image forming apparatus main body of the present invention can be connected to a post-processing device having a second switchback mechanism for reversing the front and back of the paper, and the first switchback for reversing the front and back of the paper. A mechanism, a discharge port for discharging a sheet on which an image is formed on one side surface to the post-processing device, and a receiving port for receiving the paper whose surface is reversed by the second switchback mechanism from the post-processing device. When not connected, the first switchback mechanism is used, and when the post-processing device is connected, the second switchback mechanism is used to reverse the front and back of the paper to form images on both sides of the paper. .

  Here, from the viewpoint of simplifying the configuration of the apparatus and reducing the size and weight of the apparatus, it is preferable to use, as the first switchback mechanism, a discharge roller pair that discharges the sheet to the discharge tray.

  Further, from the viewpoint of smoothly discharging and receiving the sheet to the post-processing apparatus, it is preferable to provide a discharge roller pair and a reception roller pair at the discharge port and the reception port. In this case, from the viewpoint of reducing the size and weight of the apparatus, the discharge port and the receiving port are adjacent to each other, and the discharge roller pair and the receiving roller pair are pressed against one drive roller by two driven rollers. It is preferable to be constituted by a triple roller.

  According to the invention, the image forming apparatus main body described above is connected to a post-processing device having a second switchback mechanism for reversing the front and back of the paper, and the second switchback mechanism is used to change the front and back of the paper. An image forming apparatus is provided that forms an image on both sides of a sheet by being inverted.

  Here, from the viewpoint of increasing the double-sided image forming speed, as the second switchback mechanism, a driving roller that can be rotated in the forward and reverse directions, and a driven roller that can be moved to a pressure contact position and a separation position with respect to the driving roller. When a sheet is sandwiched between a pair of discharge rollers provided at the discharge port or a pair of reception rollers provided at the reception port, the pair of reverse rollers is sandwiched at the same time. It is desirable to provide it at a position where it can. Further, until the trailing edge of the sheet discharged from the discharge port of the apparatus main body leaves the discharge roller pair, the driven roller is moved from the separation position to the pressure contact position, and the sheet is held between the reverse roller pair, and the sheet is When the paper is transported in the opposite direction to the discharge port and transported to a predetermined position, the drive roller is rotated in the reverse direction to feed the paper in the direction of the receiving port of the apparatus main body, and a pair of receiving rollers provided at the receiving port of the apparatus main body It is desirable to move the driven roller to the separation position when the leading end of the sheet is held between the two.

  In the image forming apparatus of the present invention, the first switchback mechanism that reverses the front and back of the paper, the discharge port that discharges the paper on which the image is formed on one side surface to the post-processing device, and the second switchback mechanism are reversed. And a receiving port for receiving the received paper from the post-processing device, and is connectable to the post-processing device having the second switchback mechanism. When the post-processing device is not connected, the first switchback mechanism is used, and the post-processing device is used. Is connected, the second switchback mechanism is used to reverse the front and back of the paper to form images on both sides of the paper. Thus, when priority is given to the device installation area being narrower than the double-sided image formation speed, only the apparatus main body is installed, and when priority is given to faster double-sided image formation speed than the device installation area, the device main body The user can select the installation form of the apparatus depending on what is prioritized, such as connecting the post-processing apparatus in parallel.

  At this time, if a pair of paper discharge rollers for discharging paper to the paper discharge tray is used as the first switchback mechanism, the configuration of the apparatus can be simplified and the apparatus can be reduced in size and weight.

  Further, if a pair of discharge rollers and a pair of reception rollers are provided at the discharge port and the reception port, it is possible to reliably and smoothly discharge and receive a sheet to the post-processing apparatus. Here, when the discharge port and the receiving port are adjacent to each other, and the discharge roller pair and the receiving roller pair are configured by a triple roller in which two driven rollers are pressed against one drive roller, Small and lightweight.

  And as a 2nd switchback mechanism, while using the reverse roller pair which consists of a drive roller which can be rotated in the direction of forward / reverse, and a driven roller which can move to this press roller position and a separation position, The reversing roller pair is provided at a position where the sheet can be nipped simultaneously when the sheet is nipped by the discharge roller pair provided at the discharge port or the receiving roller pair provided at the receiving port. Then, by the time when the trailing edge of the paper discharged from the discharge port of the apparatus body leaves the discharge roller pair, the driven roller is moved from the separation position to the pressure contact position, and the paper is pinched by the reverse roller pair to discharge the paper. When the paper is conveyed in the opposite direction to the outlet and conveyed to a predetermined position, the drive roller is rotated in the opposite direction to feed the paper in the direction of the inlet of the apparatus main body, and to the receiving roller pair provided at the inlet of the apparatus main body. When the leading end of the sheet is pinched, the driven roller is moved to the separation position. By controlling in this way, it is possible to carry the paper into and out of the second switchback mechanism in parallel, and the double-sided image forming speed can be further increased.

  Hereinafter, an image forming apparatus main body and an image forming apparatus of the present invention will be described with reference to the drawings. Note that the image forming mechanism in the apparatus main body and the paper conveyance path including the circulation conveyance path are the same as those in the above-described conventional one, and therefore the description thereof will be omitted here, and the following description will be focused on the parts different from the conventional apparatus main body. explain. Further, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. The image forming apparatus of FIG. 1 includes an image forming apparatus main body (hereinafter sometimes referred to as “apparatus main body”) 1 and a stapler (post-processing apparatus) 2. The stapler 2 used in this embodiment includes a switchback mechanism and a staple mechanism, and is a conventionally known one. The post-processing apparatus that can be used in the present invention is not particularly limited as long as it has a switchback mechanism, and a stapler, a punch unit, a saddle stitching (bookbinding) unit, or the like can be used.

  The apparatus main body 1 of the present invention is greatly different from the conventional apparatus main body in that a discharge port 11 for discharging paper to the stapler and a receiving port 12 for receiving paper from the stapler are provided. In the apparatus main body 1 in this figure, the discharge port 11 and the receiving port 12 are adjacent to each other in the vertical direction, and the discharge roller pair 131 and the receiving roller pair 132 are provided at the discharge port 11 and the receiving port 12. Of course, the discharge port 11 and the receiving port 12 may be provided at positions separated from each other, but it is desirable to provide the discharge port 11 and the receiving port 12 adjacent to each other from the viewpoint of simplification of the structure and miniaturization of the apparatus.

  When the discharge port 11 and the receiving port 12 are provided adjacent to each other, as shown in FIG. 2, two driven rollers 14a and 14b are brought into pressure contact with one drive roller 13 to form a triple roller. 13 and the driven roller 14a are preferably a discharge roller pair 131, and the driving roller 13 and the driven roller 14b are preferably a receiving roller pair 132. With such a configuration, the number of rollers can be reduced by one as compared with the case where the discharge roller pair 131 and the receiving roller pair 132 are provided separately, and the drive control of one drive roller 13 is sufficient, so the structure and control can be simplified. .

  In the apparatus having the structure shown in FIG. 1, when an image is formed only on one side of a sheet, the sheet on which the toner image is fixed by the fixing roller pair 85 is sent to the sheet discharge roller pair 86 by the branching claw 61 and discharged. It is discharged to the tray 80.

  When a series of sheets on which image formation has been performed on one side is bound and discharged, the sheet P1 is sent to the conveying roller pair 87 by the branching claw 61 and further discharged by the branching claw 62 as shown in FIG. 131. Then, the sheet P1 discharged from the discharge roller pair 131 is sent to the stapler 2, and is sent to the reversing roller pair (second switchback mechanism) 21 by the branching claw 63 ((a) in the figure).

  As shown in FIG. 1, the reversing roller pair 21 includes a driving roller 21a that can rotate in forward and reverse directions, and a driven roller 21b that is provided so as to be movable between a pressing position and a separation position with respect to the driving roller 21a. Become. As shown in FIG. 3B, when the paper P1 is fed, the driven roller 21b comes into pressure contact with the driving roller 21a, and the leading edge of the paper is held at the nip portion of the pair of reverse rollers 21, and the paper is opened as it is. Send in the opposite direction to part 25. When the rear end portion of the paper P1 passes through the branching claw 63, the rotation direction of the driving roller 21a is reversed. As a result, the sheet is fed to the stacker 23 through the conveying roller pairs 31 and 32 in a state where the front and back sides are reversed ((c) in the figure). At this time, when the leading end of the sheet P1 is sandwiched between the conveyance roller pair 31, the driven roller 21b of the reverse roller pair 21 moves to the separation position. Thus, the reverse roller pair 21 can discharge the paper P1 and receive the next paper P2 at the same time.

  The sheets are temporarily stored in the stacker 23 until a series of sheets are conveyed. When a series of sheets are stored in the stacker 23, the stapler 22 is driven to bind the series of sheets, and is conveyed to the discharge roller pair 34 by the conveyance roller pair 33 and discharged to the tray 24.

  Next, a case where images are formed on both sides of a sheet at high speed will be described. FIG. 4 shows a paper transport route. The sheet P on which the toner image is formed on one side by the image forming mechanism and the toner image is heated and fixed by the fixing roller pair 85 is sent to the conveying roller pair 61 by the branching claw 61 and further discharged by the branching claw 62. Sent to. Then, the sheet P1 is discharged to the stapler 2 by the discharge roller pair 131 and is sent to the reverse roller pair 21 by the branching claw 63 ((a) in the figure).

  When the leading edge of the sheet P1 is clamped by the reversing roller pair 21, the rear end portion of the sheet P1 is continuously clamped by the discharge roller pair 131. Then, the sheet P is conveyed downward in the figure by the reverse roller pair 21, and when the rear end of the sheet P1 is disengaged from the discharge roller pair 131, the reverse roller pair 21 reversely rotates and the branching claw 63 swings clockwise. To do. As a result, the sheet P1 is sent out toward the receiving port 12 (FIG. 4B). When the leading end of the sheet P1 is sandwiched between the receiving roller pair 132 of the receiving port 12, the driven roller 21b of the reverse roller pair 21 is moved to the separation position. As a result, the next paper P2 can be carried in while carrying out the paper P1, and the speed when images are formed on both sides can be increased (FIG. 3C). Then, when the rear end portion of the previous paper P1 leaves the reversing roller pair 21, the driven roller 21b is moved to the pressure contact position to prepare for the next paper P2 clamping / conveyance. Such an operation is repeated until a series of image forming processes is completed.

  Continuing the description with reference to FIG. 1, the sheet on which images are formed on both sides passes through the fixing roller 85, is sent to the paper discharge roller pair 86 by the branching claw 61, and is discharged to the paper discharge tray 80. On the other hand, when discharging a series of sheets in a bound state, the sheet on which images are formed on both sides is sent to the conveying roller pair 87 by the branching claw 61 through the fixing roller 85 and further discharged by the branching claw 62. It is sent to the roller pair 131. The paper discharged from the discharge roller pair 131 is sent to the inside from the opening 25 of the stapler 2.

  The paper on which images are formed on both sides does not need to be switched back because the first image-formed surface is the back side. Accordingly, the sheet is fed to the stacker 23 as it is, with the branching claw 63 swinging clockwise from the state shown in the figure. In the same manner as described above, the stacker 23 waits for the end of image formation of a series of sheets, and the series of sheets is bound by the stapler 22 and discharged to the discharge tray 24 by the discharge roller pair 34.

  In order to avoid the reverse of the order of the continuous sheets of paper when the sheets with images formed on both sides are discharged to the tray 80 in the apparatus main body 1, the back image of the original is first formed on the sheets, and then There is an apparatus that employs a method of forming a front image on a sheet. When an apparatus adopting such a system is used as the apparatus main body, as shown in FIG. 3, the pair of reverse rollers 21 of the stapler 2 is used to switch back the paper and send it to the stacker 23. .

  Of course, when the image is formed on both sides of the paper when the stapler 2 is not attached, the front and back sides of the paper are reversed using the pair of paper discharge rollers of the apparatus main body and the image is formed on both sides of the paper, as in the past. (See FIG. 5).

  In the apparatus of FIG. 1 in which the stapler 2 is provided side by side on the apparatus main body 1, the time required for single-sided printing of 10 sheets of A4 size paper and double-sided printing of 5 sheets of the same size using the switchback mechanism of the stapler. As a result of measuring the time required for each and calculating the ratio of the latter time to the former, the double-sided printing speed was much faster than in the past, 90%.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus main body and an image forming apparatus of the present invention. It is an enlarged view of the vicinity of the discharge port and receiving port of an apparatus main body. FIG. 10 is a diagram illustrating a sheet conveyance path when sheets are bound and discharged by a stapler. FIG. 4 is a diagram illustrating a sheet conveyance path when a sheet is reversed using a pair of reversing rollers of a stapler to form an image on both sides of the sheet. FIG. 4 is a diagram illustrating a sheet conveyance path when an image is formed on both sides of a sheet in the apparatus main body.

Explanation of symbols

1 Device body (image forming device body)
2 Stapler (post-processing equipment)
DESCRIPTION OF SYMBOLS 11 Discharge port 12 Receiving port 13 Drive roller 14a, 14b Follower roller 21 Switchback roller pair (2nd switchback mechanism)
21a Drive roller 21b Driven roller 86 Discharge roller pair (first switchback mechanism)
131 discharge roller pair 132 receiving roller pair P1, P2 paper

Claims (7)

An image forming apparatus main body capable of connecting a post-processing apparatus having a second switchback mechanism for reversing the front and back of paper,
An image forming means, a first switchback mechanism for reversing the front and back of the paper, a discharge port for discharging the paper on which one side has an image to the post-processing device, and a paper whose front and back are reversed by the second switchback mechanism A receiving port for receiving from the aftertreatment device,
When the post-processing device is not connected, the first switchback mechanism is used, and when the post-processing device is connected, the front and back of the paper are reversed using the second switchback mechanism to form images on both sides of the paper. An image forming apparatus main body.   The image forming apparatus main body according to claim 1, wherein a pair of paper discharge rollers that discharge paper to a paper discharge tray is used as the first switchback mechanism.   3. The image forming apparatus main body according to claim 1, wherein a discharge roller pair and a receiving roller pair are provided at the discharge port and the receiving port.   The image forming apparatus according to claim 3, wherein the discharge port and the receiving port are adjacent to each other, and the discharge roller pair and the receiving roller pair are triple rollers in which two driven rollers are pressed against one drive roller. Body.   A post-processing device having a second switchback mechanism for reversing the front and back of the paper is connected to the image forming apparatus main body according to any one of claims 1 to 4, and the front and back of the paper are placed using the second switchback mechanism. An image forming apparatus that reverses and forms images on both sides of a sheet. As the second switchback mechanism, a pair of reversing rollers including a driving roller that can rotate in the forward and reverse directions and a driven roller that can move to the pressure contact position and the separation position with respect to the driving roller are used.
6. The reversing roller pair is provided at a position where a sheet can be nipped simultaneously when a sheet is nipped by a discharge roller pair provided at the discharge port or a receiving roller pair provided at the receiving port. Image forming apparatus.   By the time when the trailing edge of the sheet discharged from the discharge port of the apparatus body leaves the discharge roller pair, the driven roller is moved from the separation position to the pressure contact position so that the sheet is sandwiched by the reverse roller pair, and the sheet is separated from the discharge port. When the paper is transported in the opposite direction and is transported to a predetermined position, the drive roller is rotated in the reverse direction to feed the paper in the direction of the receiving opening of the apparatus main body, and the leading edge of the paper is placed on the receiving roller pair provided at the receiving opening of the apparatus main body The image forming apparatus according to claim 6, wherein the driven roller is moved to the separation position when the portion is clamped.

Images