JP2002167097A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device for forming images on both surface of papers which realizes the reversal of front and back surfaces of the paper with a high quality, by compactly switching back the paper without damaging and occupying no space inside the device body. SOLUTION: The image forming device is provided with a device body 10 in which an image is formed on one surface of a paper P, the paper P is conveyed from a delivery port 31 at a side surface, front and back surfaces are reversed and an image is formed on a back surface of the paper P carried from a lower entrance 32; and a switch back device 40 in which front and back surfaces of the paper P are reversed by downwardly descending the paper P carried from the delivery port 31 and switching back it, the paper P is conveyed into the entrance 32 and the paper P switched back is delivered to paper delivery trays 42a, 42b at an opposite side of the device body 10. In the switch back device 10, while a restriction member 52 brings the paper P downwardly descended to a guide member 51 side, the guide member 51 guides it so as to curve to the device body 10 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an apparatus for forming an image on both sides by transporting a sheet by switching it back.

[0002]

2. Description of the Related Art Conventionally, there has been known an apparatus which records received image data on a sheet of paper using a recording medium such as toner to form an image. Such an image forming apparatus is, for example, a printer or a copier. In some cases, paper is conveyed so that images can be formed on both sides.

For example, the image forming apparatus shown in FIG. 6 guides a sheet P loaded in a sheet cassette 101 at a lower portion of the apparatus main body 100 into a transport path R1 and places the sheet P on a sheet discharge table 102 arranged at an upper portion. The sheet P in the sheet cassette 101 is ejected by a call roller 103 which presses against the leading end of the sheet P and is sent to a sheet ejection roller pair 106 via a pair of conveying rollers 104 and a pair of fixing rollers 105. The paper is discharged onto the transfer paper discharge table 102.

The toner image formed on the photoconductor drum 107 is transferred onto the upper surface of the paper P by the conveyance roller pair 104 being conveyed to a recording unit (image forming position) by the photoconductor drum 107. Fixing roller pair 1
05 is heated and pressed to fix the transferred image. After that, the switching claw 108 guides the conveying direction downstream of the fixing roller pair 105 in the re-conveying path R2, and The image can be transferred and fixed on the rear surface by being conveyed again to the recording unit by the body drum 107. In the re-transport path R2, the fed paper P is transported by the driving roller 109 and the pair of rollers 11
After the rolls 0 and 111 are rolled up and the upper and lower surfaces are reversed, the transport direction is reversed to switch back, so that the paper P, which has been turned over to the recording unit of the photosensitive drum 108, is returned to the transport path R1.

[0005]

However, in such a conventional image forming apparatus, the photosensitive drum 10
7, a route R2 for switching back the paper P and re-conveying the paper P is constructed below the recording unit by the paper cassette 1
01 occupies the upper space S, which hinders the addition of paper cassettes of different sizes and the like, and that if the forcible addition is made, the apparatus body 100 may become too high. was there.

In order to solve this problem, a configuration as shown in FIG. 7 can be considered. 7 includes a transport roller pair 104, a fixing roller pair 10
5, the paper discharge roller pair 106 and the photosensitive drum 107 are vertically arranged to form a substantially vertical transport path R3, and the discharge roller pair 1 is at the same height as the paper discharge roller pair 106.
16, the reversing roller pair 117 is arranged to form the re-transport path R4, and the switching claw 108 guides the transport direction of the sheet P to the outside of the apparatus main body 100 on the re-transport path R4 downstream of the fixing roller pair 105. Accordingly, the sheet P carried out of the apparatus main body 100 by the carry-out roller pair 116 can be guided downward in a state where the reversing roller pair 117 hangs down, and then the conveyance direction can be reversed to reverse the front and back. The paper P is fed by the carry-in roller pair 118 to the transport roller pair 1.
The image can be formed on both sides by returning to the transport path R3 from just before 04.

However, in the image forming apparatus shown in FIG. 7, the paper P on which an image has been formed on one side is again conveyed to the recording section by the photosensitive drum 107 to transfer and fix the image on the back side. While the sheet P is being transported, the means arranged outside the apparatus body 100 is
4 makes it possible to stack the other paper cassettes 121 on top of the paper cassette 101 by realizing the switchback more compactly, but without making the apparatus body 100 extremely large.
In order to meet the recent demand for color images, the photoconductor drums of the respective colors are arranged side by side on the transport path R3.
0 is increased, and since the transport path R4 is arranged on the calling side of the paper cassette 101 or the like, there is a problem that the operation of opening the transport path R3 becomes complicated.

In order to solve these problems, a configuration as shown in FIG. 8 can be considered. In the mounted image forming apparatus shown in FIG. 8, the fixing roller pair 105 and the paper discharge roller pair 106 are arranged on the opposite side of the conveying roller pair 104 (arranged in the same manner as shown in FIG. 6). 10
4 and a fixing roller pair 105, a transport path R5 in which photosensitive drums 127 for each color can be arranged in parallel,
On the downstream side of the fixing roller pair 105, the switching claw 108 directs the transport direction to the outside of the apparatus main body 100 (the opposite side from FIG. 7), and after the discharge roller pair 116 transports the paper P,
Is transported again into the apparatus main body 100 and the re-conveying roller pair 12
8 guides the re-conveyance path R6 returning from the front of the conveyance roller pair 104 to the conveyance path R5, thereby realizing re-conveyance of the sheet P to the recording unit by the photosensitive drum 127. The sheet P having an image formed on one side carried out by the sheet 116 is turned down after the reversing roller pair 117 disposed below is moved downward, and then turned over, and the carry-in roller pair 118 is re-conveyed. 12
8, image formation on both sides is realized.

However, in the image forming apparatus shown in FIG. 8, the carry-in roller pair 118 disposed below the carry-out roller pair 116 is carried into the apparatus main body 100, and is thus received from the carry-out roller pair 116. The reversing roller pair 117 for lowering the sheet P is disposed at the position of the height H2 which is further lower, and the large size that can be processed with the height H1 of the reversing roller pair 117 shown in FIG. For example, when an attempt is made to reverse the paper P of A3 size, there is a problem that the end may collide with the floor and be damaged.

Accordingly, the present invention provides a high-quality front and back side of a sheet by enabling the sheet to be compactly switched back without occupying the space in the apparatus body and without damaging it. It is an object of the present invention to provide an image forming apparatus capable of reversing image quality.

[0011]

Means for Solving the Problems A first method for solving the above problems is described below.
In the invention, an image forming means for forming an image on one side of a conveyed sheet, a sheet conveying means for conveying a sheet to an image forming position by the image forming means, and an image formed on one side from the sheet conveying means An image forming apparatus for forming an image on both sides of a sheet, comprising: a sheet reversing unit that receives the sheet, switches the sheet back and upside down, returns the sheet to the sheet conveying unit, and conveys the sheet again to the image forming position. The apparatus main body has a carry-out port opened on the side of the apparatus main body so that the paper conveying means conveys the paper out of the main body, and the re-conveying means carries the paper, which is turned upside down, into the main body and returns it to the paper conveying means. A carry-in port that opens below the carry-out port on the side of the apparatus body, and the re-conveying means receives the sheet carried out of the apparatus body from the carry-out port and lowers the sheet, and then changes the carrying direction of the sheet. A switchback unit is transported into the apparatus body from the entrance by rotation, it is characterized in that it has a guide member for guiding the switchback means in a direction to bend the paper coming is lowered downward.

According to the present invention, the sheet conveying means conveys the sheet to the image forming position and conveys the sheet from the carry-out port on the side of the apparatus body, while the re-conveying means conveys the sheet conveyed by the sheet conveying means to the image forming position again. The re-transporting means reverses the front and back sides of the sheet by lowering the sheet downward and switching back the sheet between the carry-out port and the carry-in port, while allowing the sheet to be carried in from the carry-in port below the carry-out port.
Therefore, the sheet conveying means can be laid out so that the sheet crosses the inside of the apparatus main body, and the switchback means of the re-conveying means can switch the sheet vertically and compactly outside the apparatus.

When the sheet is turned upside down by switchback in the vertical direction, the sheet is lowered while being guided by the guide member so as to be curved. Therefore, even when the distance from the switchback means to the installation surface of the apparatus is shorter than the length of the paper, the descending distance to reach the installation surface can be extended, and after the arrival, it follows the installation surface. Can be guided.

According to a second aspect of the invention for solving the above-mentioned problems, in addition to the features of the first aspect, the guide member is curved in a direction approaching a side surface of the apparatus main body.

According to the present invention, the sheet that is lowered while being guided by the guide member is curved in a direction approaching the side surface of the apparatus main body. Therefore, the paper does not flow outside the apparatus.

According to a third aspect of the present invention for solving the above-mentioned problems, in addition to the specific features of the first or second aspect of the present invention, the paper dropped by the switchback means is lowered on the side close to the guide member. In this case, a regulating member for regulating the pressure is provided.

According to the present invention, the sheet which is guided downward by the guide member and is lowered is regulated to the side close to the guide member. Therefore, the sheet to be lowered can be reliably guided and curved by the guide member.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 to 5 are views showing an example of a printer device to which an embodiment of the image forming apparatus according to the present invention is applied.

In FIG. 1, the printer apparatus is detachably connected to the apparatus main body 10 with a switchback device 40 for switching back the transported paper P on which an image has been formed and for reversing the front and back. The paper P on which an image has been formed by calling from any of them is transferred to the apparatus main body 1.
The paper is discharged to any one of the paper discharge tray 12 and the paper discharge trays 42a to 42c of the switchback device 40.

The apparatus main body 10 is detachably provided with an image forming unit 13 capable of forming a monochrome or color image on a sheet of paper P and a fixing unit 14 for fixing the formed image on the sheet P. The image forming unit 13 forms the transport path R5 so that the carrier belt 15 transports the sheet P obliquely upward (in the transverse direction), and along the carrier belt 15, yellow, magenta, cyan, and black are formed. The writing unit 16 scans the peripheral surface of the photoconductor drums 17Y, 17M, 17C, and 17B, which are sequentially arranged in parallel, with the laser beam L to write and form an electrostatic latent image, and the developing units 18Y, 18M, 18C, and 18
B develops the electrostatic latent image with toner and transfers the toner image to one side of the sheet P conveyed by the carrying belt 15, while the fixing unit 14 applies the pressure roller 19 heated by the built-in heater to the endless belt 20. The toner image on the sheet P received from the carrying belt 15 is fixed by rotating while being pressed while being pressed, and an image is formed on the sheet P. The writing unit 16 irradiates laser light L emitted from a laser diode (not shown) to a two-stage polygon scanner 16a based on the received yellow, magenta, cyan, and black image data, and outputs the mirror light to a mirror. The photoconductor drum 17Y is polarized by the group 16b.
An electrostatic latent image is written by scanning over 17M, 17C and 17B.

The paper P is made of plain paper or OHP having different sizes.
Paper cassettes 11a and 11 for loading and storing films and the like
Calling belt 2 on the tip side of b (right side in the figure of the apparatus main body 10)
When the separation roller 22 that is called and pressed in contact returns the extra paper P and separates it one by one, the separation roller 22 is transferred to the registration roller pair 25 in front of the image forming unit 13 via the conveyance roller pair 23 and the convergence roller pair 24. The image forming unit 13 and the fixing unit 1
4 and an image is formed, the branch roller pair 2
6. The sheet is transferred to the discharge roller pair 27 at the upper portion of the apparatus main body 10 via the transport roller pair 23, so that the front and back sides are reversed so that the image formed immediately before faces downward and in the page order, and The paper is ejected and stacked on the paper 12. The sheet P from the sheet cassette 11b is transferred from the pair of converging rollers 24 to the pair of registration rollers 25 by using a pair of converging rollers 29 described later. The apparatus main body 10 has a hand tray 35 that can be opened and closed on the right side surface in the drawing, from which the paper P can be directly supplied to the registration roller pair 25.
An opening / closing door 36 is arranged below the sheet P so that the jammed sheet P can be removed at the time of calling.

Further, the apparatus main body 10 passes the sheet P via a re-transport path R6 comprising a pair of transport rollers 28 and a pair of converging rollers 29 arranged so as to be in parallel below the support belt 15 (transport path R5). By transferring the image to the convergence roller pair 24 and the registration roller pair 25, it is possible to convey the image to the image forming unit 13 again to form an image.
Reference numeral 8 denotes an unillustrated branching claw disposed on the downstream side of the pair of branching rollers 26 for switching the transport direction of the sheet P on which an image has been formed on one side by the image forming unit 13 so that the sheet P is unloaded from the unloading roller pair. 30 is carried out from a carry-out port 31 opening on the left side surface of the apparatus main body 10 to a switchback device 40 which is an external device, and then the switchback device 40 is turned upside down and opened below the carry-out port 31. The sheet P carried in from the opening 32 is receivably received by the image forming unit 13. Therefore, the sheet P on which an image has been formed on one side by being transported from the paper cassettes 11a and 11b to the image forming unit 13 can be re-transported to the image forming unit 13 with the switchback device 40 turned upside down. Paper P in 10
The image can be formed on the back surface of the paper P and the image can be formed on both surfaces without reversing the front and back. At this time, the image of the even page (for example, the second page) is
After forming an image of an odd page (for example, the first page) on the back surface of the sheet P after forming the sheet P on one side of the sheet P, the sheet P discharged by the sheet discharge roller pair 27 at the top of the apparatus main body 10 is
It can be loaded in page order.

The switchback device 40 is connected to the switchback device 40 shown in FIG.
As shown in (2), after the sheet P carried out from the carry-out port 31 of the apparatus main body 10 is received by the upper reversing roller pair 43, guided so as to descend downward from the tip, and delivered to the lower reversing roller pair 44, When the lower reversing roller pair 44 reverses the timing at which the rear end of the sheet P is nipped and switches back, and switches the conveyance direction with a branch claw (not shown), the input roller pair 46 feeds the sheet P, which has been turned upside down, to the apparatus. It can be delivered from the carry-in port 32 of the main body 10 to the carry roller pair 28 of the re-transport path R6. The switchback device 40 reverses the timing at which the upper reversing roller pair 43 pinches the rear end of the sheet P in accordance with the designation of the sheet discharge destination, switches back, and switches the transport direction with a branch claw (not shown). Alternatively, the lower reversing roller pair 44 reverses the timing at which the rear end of the paper P is nipped to switch back, and switches the transport direction with a branch claw (not shown), thereby discharging the paper P with the front and back reversed. The pairs 47 and 48 can discharge paper onto the paper discharge trays 42a and 42b and stack them in the page order, and also, in the transport direction of the paper P carried out from the carry-out port 31 of the apparatus main body 10. Is switched to a transport path above the reversing roller pair 43 by a branch claw (not shown), and is transferred to the discharge roller pair 49 as it is.
The sheet P can be discharged and stacked on the sheet discharge tray 42c with the surface on which the image is formed immediately before facing up, without turning over the sheet P.

Therefore, the sheet P is turned upside down by a compact switchback in the up and down direction by the switchback device 40 connected to the outside of the apparatus main body 10 and then returned to the inside of the apparatus main body 10 and images are formed on both sides of the paper P. Can be formed, and the sheets P in the page order can be stacked on the sheet discharge trays 42a and 42b. When the OHP or the like is manually fed as the sheet P, the sheet is discharged as a sheet discharge destination. By designating the tray 42c, the paper P can be discharged and stacked without deteriorating the quality of the image formed on the surface without applying a load when the sheet P is curved and reversed. In addition, the specification of the discharge destination of the paper P is as follows.
It may be set arbitrarily according to the type of image and the like. For example, when the output trays 42a to 42c are switched according to the request source of the image to be printed out, or when combined with a copy machine or a facsimile machine, etc. May be set so that the paper P by printout and the paper P by copy or facsimile reception are discharged separately.

The switchback device 40 is hung below the lower reversing roller pair 44 and
A guide member 51 is provided on the side away from zero, and this guide member 51 has a lower end curved in a direction approaching the apparatus main body 10. Further, as shown in FIG. 2, the paper P to be nipped and lowered by the lower reversing roller pair 44 is brought closer to the upstream side of the guide member 51 so as to descend on the side close to the guide member 51 (restricted).
A regulating member 52 is provided. The guide member 51
May be hooked and attached by making use of the fact that the rod material is bent and made to return elastically, and it goes without saying that a plate material may be used.

Therefore, as explained with reference to FIG.
The lower reversing roller pair 44, which lowers the rear end of the sheet P carried out from the carry-out port 31 of the apparatus body 10 until the rear end thereof is nipped, is disposed at a lower height H2. The guide member 51 guides the paper P even in an apparatus configuration in which the lower end of the paper P may collide with the floor (installation surface) and be damaged if the A3 size paper P is directly lowered downward. Thus, the sheet P can be curved downward to descend to the apparatus main body 10 side, and the descending distance until the paper P reaches the floor surface can be increased. Further, even if the leading end of the paper P arrives, the paper P can be guided along the floor surface and collision can be avoided. Also, the paper P
Does not flow from the side of the device to the outside, and is not stepped on by a pedestrian.

Further, as shown in FIG. 3, the paper P is prevented from falling downward while being free.
5 can be reliably guided by the guide member 51 by the regulating member 52, and the paper P is curled, and the leading end of the paper P impinges on the waste heat louver 38 shown in FIG. 4 as shown in FIG. It is possible to avoid being stopped and damaged.

As described above, in the present embodiment, the sheet P is carried out from the carry-out port 31 on the side of the apparatus main body 10 and turned over by the switchback device 40, and then the carry-in port 32 is used.
, The paper cassette 11b and the photosensitive drums 17Y to 17B can be arranged, and the switchback device 40 of the switchback device 40 uses a compact switchback in the vertical direction without increasing the size of the device. Even when a configuration is adopted in which the front and back sides are reversed, the paper P to be switched back is guided by the guide member 51 and the regulating member 52 so as to be curved in a direction closer to a position closer to a position separated from the apparatus main body 10.
It is possible to hold the sheet P down to the floor surface, and to prevent the paper P from slipping on the floor surface and being damaged even if the leading end reaches.

Accordingly, it is possible to secure a space in the apparatus main body 10 and to diversify the formation of color images on both sides of paper P of different sizes, and to turn the paper P upside down without being damaged. Can be done.

As another aspect of the present embodiment, although not shown, the guide path is used as a guide member so that the sheet P to be guided downward for switchback is lowered in a meandering manner. It may be formed, in which case the distance to reach the floor can be extended longer.

Further, the guide member 51 may be mounted with the curving direction reversed, but the present embodiment is more preferable because the guide member 51 can be curved toward the apparatus main body 10.

[0032]

According to the present invention, the paper can be laid out so as to traverse the inside of the apparatus main body by carrying out the paper from the carry-in port after taking out from the carry-out port on the side of the apparatus main body. By lowering the sheet and switching back outside, the sheet can be turned upside down in a compact manner, and a space for additional space inside the main body can be secured without increasing the external size of the apparatus.

At this time, the sheet to be switched back is lowered while guiding it to be curved,
The descending distance to the installation surface of the device can be gained, and after reaching, the device can be slid on the installation surface. Further, since the sheet is curved in a direction approaching the side surface of the apparatus main body, the sheet does not flow outside the apparatus and is not damaged by a person passing around. Further, by restricting the sheet so as to approach the guide member, the sheet can be surely curved to secure a descending distance.

As a result, without occupying the space in the apparatus main body and without damaging it, images can be formed on both sides by reversing the front and back of the sheet with high quality.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of an image forming apparatus according to the present invention, and is a front perspective view illustrating an entire configuration thereof.

FIG. 2 is a partial front perspective view illustrating the operation.

FIG. 3 is a partial front perspective view for explaining the effect.

FIG. 4 is a partial perspective view for explaining the effect.

FIG. 5 is a partial front perspective view for explaining the effect.

FIG. 6 is a front perspective view showing the prior art.

FIG. 7 is a front perspective view showing a conventional technique different from that of FIG. 6;

FIG. 8 is a front perspective view for explaining the problem of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Apparatus main body 11a, 11b Paper cassette 12 Paper discharge table 13 Image forming unit 14 Fixing unit 15 Carrier belt 16 Writing unit 17B-17Y Photoconductor drum 30 Outgoing roller pair 31 Outgoing outlet 32 Inlet 38 Louvre 40 Switchback device 42a- 42c paper discharge tray 43 upper reversing roller pair 44 lower reversing roller pair 46 carry-in roller pair 47-49 paper discharge roller pair 51 guide member 52 regulating member

Claims (3)

[Claims] An image forming means for forming an image on one side of a conveyed sheet, a sheet conveying means for conveying a sheet to an image forming position by the image forming means, and an image forming on one side from the sheet conveying means. An image forming apparatus for forming an image on both sides of a sheet, comprising: a re-conveying unit for returning the sheet, which has been turned upside down by receiving and switching back the sheet, to a sheet conveying unit and conveying the sheet again to an image forming position. The apparatus main body has a carry-out opening that is opened on the side of the apparatus main body so that the paper conveying means conveys the paper out of the main body, and the re-conveying means carries the paper, which is turned upside down, into the main body and sends the paper to the paper conveying means. A carry-in port that opens below the carry-out port on the side of the apparatus main body to return the sheet; An image forming apparatus, comprising: a switchback means for inverting a sheet and carrying it into the apparatus main body from a carry-in port; and a guide member for guiding a sheet descending downward by the switchback means in a curving direction. . 2. The image forming apparatus according to claim 1, wherein said guide member is curved in a direction approaching a side surface of the apparatus main body. 3. The device according to claim 1, further comprising a regulating member for regulating a sheet which is lowered by the switchback means so as to descend on a side close to the guide member. Image forming device.