JP2001225971A - Image forming device - Google Patents

Abstract

(57) [Summary] (Problems corrected) [Problem] To provide an image forming apparatus in which a single-sided machine can be changed to a double-sided machine without changing a front surface of a machine accessed by an operator, and an optional paper feeding unit can be easily added. . A sheet discharging unit having a path for re-transporting a transfer sheet that has passed through a fixing device from the rear of the apparatus to a transfer roller in order to transfer an image to the other surface of the transfer sheet.
0, a transport unit 50 and a reversing unit 60, and a reversing roller 63 for reversing the transfer paper before transporting it again to the transfer roller 14.
And a switching lever 41 for switching between discharging and re-feeding the transfer sheet having the image transferred to one side thereof, and an optional sheet feeding unit 70. A boss 73 inserted into the positioning hole 91 is provided upright on the upper surface of the paper unit 70, so that the optional paper supply unit 70 can be easily attached and detached.

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 used for a copying machine, a printer, a facsimile or the like.

[0002]

2. Description of the Related Art As an image forming apparatus used in a copying machine, a printer, a facsimile or the like, an electrophotographic apparatus such as a PPC or an LBP is known. Such an electrophotographic apparatus forms an electrostatic latent image on a photoreceptor, develops the image by a developing device to obtain a toner image, and transfers the toner image onto transfer paper. As the transfer paper, plain paper can be used. Therefore, it has been widely spread, and with the spread, a reduction in size and weight has been demanded. In response to this request, in order to shorten the transfer path length of the transfer paper and improve operability such as jam handling, a paper feed unit was arranged at the bottom and a fixing / discharge unit was arranged at the top by front operation. 2. Description of the Related Art An image forming apparatus employing a substantially vertical transport path is employed in small and medium-sized models.

In recent years, demand for so-called double-sided printing for forming images on both sides of a transfer sheet has been increasing, and the size of the transfer sheet has been reduced by employing the above-described front-side operation and employing a substantially vertical conveyance path. 2. Description of the Related Art An image forming apparatus has been proposed in which double-sided printing is enabled by adding a double-sided apparatus for transferring an image to the reverse side of the reverse side, as disclosed in, for example, JP-A-6-110274. Japanese Patent Application Laid-Open No. Hei 6-110
In the image forming apparatus disclosed in Japanese Patent No. 274, a double-sided apparatus is mounted from the upper part of the apparatus main body to the front front side. In addition, a transfer switching mechanism is provided in front of the paper discharge unit, and the transfer paper re-fed for double-sided printing is conveyed to the upper part of the normal paper discharge unit, where it is switched back and passed through the front of the apparatus. The paper is fed again.

[0004]

As described above, the image forming apparatus employing the front operation / substantially vertical transport path has a structure in which the front is opened and the operation is performed in the case of jam clearance or supply replacement. In many cases, an operation panel and the like are naturally provided on the front surface. For this reason, if the double-sided device is attached to the front of the device, the double-sided device may obstruct the opening operation, or may hinder the above operation.

[0005] Further, since the configuration of the front part of the machine greatly changes between a machine equipped with a duplex machine (double-side machine) and a machine not requiring a duplex machine (single-side machine), commonality of parts can be achieved. As a result, it is difficult to unify the products.

On the other hand, when a large amount of copying or printing is to be performed, the transfer paper in the paper feed cassette is not sufficient, and the transfer paper must be replenished frequently, causing a decrease in efficiency. Therefore, it is demanded that a paper feeding unit can be additionally provided as an option separately from the paper feeding cassette.

[0007] The present invention has been made in view of such a situation of the prior art, and an object thereof is to provide a single-sided machine without changing the basic configuration of the main body of the machine, particularly, the front surface of the machine accessed by an operator. An object of the present invention is to provide an image forming apparatus which can be changed to a duplex machine and can easily add an optional paper feed unit.

[0008]

In order to achieve the above object, a first means is to print a transfer sheet fed from a sheet stacking section located below the apparatus main body through a front side of the apparatus main body. An image forming apparatus that feeds the paper to the paper transfer unit, and fixes the transfer paper on which the image is transferred in the printing unit in a fixing unit, and then discharges the paper out of the apparatus from a discharge port above the apparatus main body. A re-feeding unit having a transport path for transporting the transfer paper again from the rear of the apparatus main body to the printing unit through the transfer paper that has passed through the fixing unit for transferring an image to the other surface of the transfer paper; A reversing mechanism provided in the re-feeding unit, for reversing the transfer paper before transporting the transfer paper to the printing unit again; Output unit that switches to output to either The provided, the lower surface of the sheet re-feeding portion positioned below the apparatus main body is characterized in that the optional paper feed unit is in the attachable.

[0009] To achieve the above object, the second means is as follows.
A transport path for transporting the transfer paper from the optional paper feed unit to the printing unit is provided in the re-feed unit located below the apparatus main body in the first means in a substantially vertical direction. And

[0010] To achieve the above object, a third means is as follows.
The refeeding unit and the optional sheet feeding unit located below the apparatus main body in the first or second means can be pulled out to the front side of the apparatus main body.

[0011] To achieve the above object, a fourth means is as follows.
The reversing machine in the third means is provided in the paper re-feeding section located below the apparatus main body.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a color image forming apparatus according to an embodiment of the present invention;

First, a single-sided color image forming apparatus will be described. FIG. 1 is a vertical sectional side view for explaining a configuration of a single-sided transfer type color image forming apparatus to which the present invention is applied.

In FIG. 1, reference numeral 1 denotes an endless photosensitive belt which is a flexible image bearing member.
It is bridged between the rotating rollers 2 and 3 and is conveyed in the direction of arrow A (clockwise) in the figure by the rotation of the rotating roller 2. In the vicinity of the lower side of the photoreceptor belt 1, a charging charger 4 as charging means for uniformly charging the surface of the photoreceptor belt 1 is provided. The photoreceptor belt 1 further includes a laser optical device 5 of a laser writing system unit serving as an electrostatic image exposure unit, and four developing devices having yellow, magenta, cyan, and black developers (toners) described later. Are provided.

Above the photosensitive belt 1, an intermediate transfer belt 10, which is an intermediate transfer member, is provided. The intermediate transfer belt 10 is laid between rotating rollers 11 and 12,
The paper is conveyed in the direction of arrow B (counterclockwise) in the figure by the rotation of the rotation roller 11. The photosensitive belt 1 and the intermediate transfer belt 10 are in contact with each other at a portion of the rotating roller 3 of the photosensitive belt 1. A conductive bias roller 13 is provided on the intermediate transfer belt 10 side of the contact portion.
Under the predetermined condition.

As a result, the photoreceptor belt 1 is uniformly charged by the charging charger 4 and then scanned and exposed by the laser optical device 5 based on the image information to form an electrostatic latent image on the surface. The image information to be exposed is monochromatic image information obtained by decomposing a desired full-color image into yellow, cyan, magenta, and black color information, and is generated by a semiconductor laser (not shown) in the laser optical device 5 based on this information. The laser beam L has been scanned and optical path adjusted by an optical device not shown. The electrostatic latent image formed here is monochrome-developed with predetermined yellow, cyan, magenta, and black toners, respectively, by a color developing device 6 that is a rotary developing device described later. Color images are sequentially formed.

Each monochrome image formed on the photosensitive belt 1 rotating in the direction of arrow A in FIG. 1 is transferred onto an intermediate transfer belt 10 rotating in the direction of arrow B in FIG. For each of the single colors of yellow, cyan, magenta, and black, the image is sequentially transferred by a predetermined transfer bias applied to the bias roller 13.

The yellow, cyan, magenta, and black images superimposed on the intermediate transfer belt 10 are collectively transferred to a transfer sheet 17a by a transfer roller 14, which is a transfer section. The transfer paper 17a is provided at the bottom of the left main body,
The sheet is stacked in a sheet cassette 17 which can be pulled out to the front side, that is, the side of the front frame 8 which is the operator side. Above the paper feed cassette 17 on the front frame 8 side, a paper feed roller 18 that pulls out the transfer paper 17a one by one from the paper feed cassette 17 is provided. The transfer paper 17a sent out from the paper feed roller 18 is transferred to a pair of transport rollers 19a and 19b and a pair of registration rollers 20 attached to the front frame 8.
The sheet is conveyed to the transfer roller 14 which is a transfer section via a and 20b. The transfer roller 14 is also attached to the front frame 8,
When the front frame 8 is set so as to cover the front surface of the apparatus main body, it is attached so as to press against the intermediate transfer belt 10. After the transfer, the transfer paper 17a is fixed by passing between the pair of fixing rollers 80a and 80b in the fixing device 80, the transfer of the full-color image is completed, and the transfer paper 17a is discharged out of the device by the pair of discharge rollers 81a and 81b. Are stacked on a tray section 82 provided at the upper rear portion of the apparatus main body. The transfer paper 17a from the reversing unit 60, which will be described later, is placed on the front frame 8 side of the paper feed cassette 17 by the transport roller pair 1.
A transfer path 17b for passing the sheets 9a and 19b is provided.

The frame structure of the apparatus main body includes a main body frame 9 as an immovable portion housing, and a front frame 8 as a front housing capable of opening a transfer path of transfer paper from a paper feed cassette 17 to a transfer roller 14. And is constituted by. A paper cassette 17 is arranged at a lower portion of the main body frame 9,
The color developing device 6 and the process cartridge are replaceably arranged at the center, and the fixing device 80 is further arranged above the color developing device 6, and a tray portion 82 which is a sheet discharge stack portion is formed at an upper rear portion. The front frame 8 is supported so as to be rotatable around a rotation support shaft (not shown) provided on a main body frame 9 serving as a rotation fulcrum. As shown in FIG. It is held by the frame 9. By releasing the holding with the main body frame 9 at the time of the jam clearance, it is possible to rotate in a clockwise direction and open, and the open state can be maintained by the power of a tension spring (not shown) or the like. As described above, the front frame 8 holds the registration roller 20, the transfer roller 14, and the like that are part of the transport path. Thus, when the front frame 8 is opened, the transfer path of the transfer paper from the paper feed cassette 17 to the transfer roller 14 is opened, and the paper jam can be performed. At this time, since only the jam processing can be performed without operating the image forming unit, there is no problem such as toner drop.

Next, a case where a two-sided apparatus is attached to the above-described color image forming apparatus will be described with reference to FIG. FIG. 2 is a vertical sectional side view for explaining a case where a double-sided device is attached to the color image forming apparatus.

The two-sided device includes a pair of paper discharge rollers 81a and 81b.
The transfer paper discharged from the pair of paper discharge rollers 81a and 81b in such a double-sided device is discharged to the outside of the device, or is sent again to the transfer roller 14 so that the first surface is transferred to the second surface of the transfer paper. Whether to perform the image forming / transferring / fixing steps in the same manner as the surface is selected. As shown in FIG. 3, the two-sided device includes a paper discharge unit 40 provided in the rear of the fixing device 80 in the transport direction, that is, an upper rear of the left main body, a transport unit 50 provided in the rear of the main body, and a It is constituted by three units of a reversing part 60 provided below, that is, at the bottom.

The paper discharge section 40 includes a pair of paper discharge rollers 81a, 81
The transfer paper 17a discharged from the pair of paper discharge rollers 81a, 81b through the fixing device 80 is disposed outside the apparatus, or is transferred to the second surface. Lever 41 for switching the transport direction to feed the paper to the transport unit 50, and a discharge roller for discharging the transfer paper 17a from the switch lever 41 to a paper discharge stack unit 43 formed on the upper surface of the paper discharge unit 40 Vs. 42
a, 42b and the transfer paper 17a from the switching lever 41
Transport roller pairs 44 for transporting the
a, 44b and 46a, 46b, and the transfer lever pair 44a, 44b, 46
a, and a pair of guide plates 45a and 45b for guiding the transfer paper 17a to the transport unit 50 through the transfer plates 17a and 46b. The transport unit 50 transfers the transfer paper 17a from the paper discharge unit 40 to the reversing unit 60.
Transport roller pairs 52a and 52b for transporting
53a, 53b, 54a, 54b, and a pair of transport rollers 52a, 52b,.
And a pair of guide plates 51a and 51b for guiding the transfer paper 17a to the reversing unit 60 through the reversing unit 60.

Therefore, the pair of paper discharge rollers 81a, 81b
The transfer path of the transfer paper 17a discharged from the printer is switched by the switching lever 41, and the transfer paper 17a to be discharged outside the apparatus is stacked on the discharge stack 43 by the pair of discharge rollers 42a and 42b. Become.
On the other hand, when the transfer sheet 17a transfers an image also to the second surface, the transfer lever pair 44a, 44b and 46a, 46 pass under the sheet discharge stack 43 by the switching lever 41.
b, and is transported to the transport section 50 through the guide plates 45a and 45b. In the transport unit 50, the transport roller pair 52a, 5
2b... 54a, 54b and guide plates 51a, 51
The transfer paper 17a is guided to the reversing unit 60 by b.

On the other hand, the reversing section 60 has three pairs of conveying rollers 62a, 62b, 67a, 67b, 68a, 68a, for conveying the transfer paper 17a from the conveying section 50 to the front frame 8 side.
68b and the transfer paper 17a from the paper discharge unit 40 are transported by these transport roller pairs 62a, 62b, 67a, 67b, 68a, 6
A pair of upper and lower guide plates 61 for guiding the passage through 8b
a and 61b, a reversible reversing roller 63, a pair of upper and lower reversing guide plates 66a and 66b positioned substantially parallel below the guide plates 61a and 61b, and a transfer sheet 17a sent from the reversing roller 63. It has a pair of transport rollers 64a and 64b for sending out to the transport path 17b of the cassette 17, and all of them are provided in the tray 60a.
a is slidably inserted into the reversing part 60 in the direction of the front frame 8. The conveyance guide plate 6 is provided on the reversing roller 63.
5, the transfer paper 17a conveyed from the conveyance section 50 by the conveyance guide plate 65 is sent out to the reversal guide plates 66a, 66b, and is also sent out from the reversal guide plates 66a, 66b. 17a is guided so as to be sent out to the conveying roller pairs 64a and 64b. A reversible drive roller 69 is provided in a transfer path of transfer paper between the pair of transfer rollers 68a, 68b and the reversing roller 63, and a driven roller 69a is provided above the drive roller 69.
A driven roller 69b is also in contact with the lower portion, and the transfer paper 17a that has passed through the guide plates 61a and 61b is conveyed to the reversing roller 63 by the driving roller 69 and the driven roller 69a. Roller 6
9b, the transfer paper 17 from the guide plates 66a, 66b
a is conveyed to the reversing roller 63. The reversing roller 63
Of course, the driving roller 69 also rotates and the rotation direction is synchronized.

Therefore, the transfer paper 17a conveyed from the conveyance section 50 is guided by the guide plates 61a and 61b and the conveyance roller pairs 62a, 62b, 67a, 67b, 68a, and 68a.
68b, between the driving roller 69 and the driven roller 69a, and then through the reversing roller 63 (toward the operator)
Transported to The conveyance guide plate 65 is in contact with the reversing roller 63.
As a result, the transfer paper 17a is sent to the reversing guide plates 66a and 66b. When the rear end of the transfer paper 17a has passed the conveyance guide plate 65, the reversing roller 63 and the driving roller 69 are rotated in the reverse direction. Thus, the transfer paper 17a is transported in the direction of the pair of transport rollers 64a and 64b by the reverse rotation of the reversing roller, and the transport path provided on the front side of the paper feed cassette 17 is used as the leading edge of the transfer paper 17a. 17b, a pair of conveying rollers 19a, 19b, a pair of registration rollers 20a,
Then, the image is transferred to the second surface of the transfer paper 17a through the same process as that of the first surface, and is discharged so as to be stacked on the discharge stack 43.

As described above, in the double-sided device for reversing the transfer paper 17a, the paper discharge unit 40 is provided at the upper rear of the apparatus main body, the conveyance unit 50 is provided at the rear of the apparatus main body, and the transfer unit 50 is provided at the bottom of the apparatus main body. Since the reversing unit 60 is provided, the front frame 8 can be freely opened and closed even if this double-sided device is attached, and jam processing and the like can be easily performed. Furthermore, since the double-sided device is attached from the upper rear to the rear of the apparatus main body and the bottom and the outside of the apparatus main body, there is no need to improve the internal structure of the color image forming apparatus as a single-sided machine. It is very easy to change to a color image forming apparatus as a duplex machine.

Next, a case where an optional sheet feeding unit is mounted below the image forming apparatus will be described with reference to FIGS. FIG. 3 is a vertical sectional side view for explaining a case where an optional paper feeding unit main body is mounted on the image forming apparatus. FIG. 4 is a view showing a case where an optional paper feeding unit main body with a paper feeding tray inserted is mounted on the image forming apparatus. FIG.

The optional paper feed unit 70 is composed of a unit body 71 composed of a front frame 8 and a rectangular frame having an open rear side of the apparatus body, and is slidably inserted in the unit body 71 in the direction of the front frame 8. And a paper feed tray 72. On the upper surface of the unit body 71, two or more positioning bosses 7 are provided at appropriate intervals.
3 are erected. A paper feed roller 74 that pulls out the transfer papers 17a one by one from the paper feed tray 72 one by one, and also conveys the transfer papers 17a drawn out by the paper feed roller 74 to the reversing unit 60, above the inside of the front side of the unit main body 71. Roller pairs 75a and 75b are provided.

On the bottom surface of the reversing section 60, a unit body 71 is provided.
When the image forming apparatus is positioned above, the unit body 71
A plurality of positioning holes 91 into which the boss 73 is inserted are formed. The reversing section 60 further transfers the transfer paper 17a from the paper feed tray 72 to the pair of transport rollers 19a and 19 of the reversing section 60.
b and a pair of transport rollers 92 for sending out the transfer paper 17a
A transfer passage 93 (FIG. 4) for transferring the sheet to the transfer passages a and 92b is provided.

As described above, the optional sheet feeding unit 7
The optional paper feed unit 70 can be increased by a simple operation such that the boss 73 is inserted into the positioning hole 91 of the reversing unit 60 on the top of the image forming apparatus. Also, the optional sheet feeding unit 70
Not only the paper feed tray 72 but also the tray 60
The drawing direction of a is both the front direction, and the replenishment of the transfer paper 17a to the paper feed tray 72 and the jam processing in the tray 60a and the paper feed tray 72 can be performed by the front drawer. Can be planned.

The timing of the switching of the switching lever 41 and the reverse rotation of the reversing roller 63 may be determined, for example, by providing a sensor near the switching lever 41 or the reversing roller 63.
What is necessary is just to detect the passage of the rear end of the transfer paper 17a.

[0032]

As is apparent from the above description, according to the first aspect of the present invention, the optional paper feeding unit can be attached to the lower surface of the re-feeding unit located below the apparatus main body. Therefore, when it is desired to add an optional paper feed unit, it is possible to easily add the optional paper feed unit simply by placing the apparatus main body on the optional paper feed unit.

According to the second aspect of the present invention, the transport path for transporting the transfer paper from the optional paper feed unit to the printing unit is provided in the re-feed unit of the apparatus main body in a substantially vertical direction. The transfer paper from the optional paper feed unit can be conveyed to the apparatus main body at the shortest distance, and the printing speed can be improved.

According to the third aspect of the present invention, the re-feeding unit and the optional paper feeding unit can be pulled out to the front side of the apparatus main body. This can be performed by pulling out the front, unifying operability, and preventing confusion of the user.

According to the fourth aspect of the present invention, since the reversing mechanism is provided in the refeeding section, maintenance of the reversing mechanism can be performed by pulling the refeeding section forward.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view for explaining a configuration of a single-sided transfer type color image forming apparatus to which the present invention is applied.

FIG. 2 is a vertical sectional side view for explaining a case where a double-sided device is attached to the color image forming apparatus of FIG. 1;

FIG. 3 is a vertical sectional side view for explaining a case where an optional sheet feeding unit main body is mounted on the image forming apparatus.

FIG. 4 is a vertical sectional side view for explaining a case where an optional sheet feeding unit main body in which a sheet feeding tray is inserted is attached to the image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor belt 5 laser optical device 6 color developing device 8 front frame 9 main body frame 10 intermediate transfer belt 14 transfer roller 17 paper feed cassette 17a transfer paper 17b transport passage 19a, 19b transport roller pair 20a, 20b registration roller pair 40 paper discharge Unit 41 Switching lever 43 Discharge stack unit 50 Transport unit 60 Reversing unit 63 Reversing roller 65 Transport guide plate 70 Optional paper feed unit 70a Tray 71 Unit body 73 Boss 80 Fixing device 81a, 81b Discharge roller pair 91 Positioning hole 93 Transport path

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masafumi Takiguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hirotaka Hatta 1-3-6 Nakamagome, Ota-ku, Tokyo Stock In Ricoh Company (72) Inventor Katsuhiro Kosuge 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Company (reference) 2H028 BA09 BA14 2H071 BA03 BA14 DA22 DA23 EA04 3F100 AA02 CA11 3F343 FA02 FB02 GA01 GB01 GC01 GD01 HA16 HB03 HB07 HC04

Claims (4)

[Claims] 1. A transfer sheet fed from a sheet stacking section located below the apparatus main body, is fed to a printing section through a front side of the apparatus main body, and the transfer section on which an image is transferred in the printing section. In an image forming apparatus that discharges the paper out of the apparatus from a discharge port above the apparatus main body after fixing the paper in a fixing unit, the image forming apparatus passes through the fixing unit to transfer an image to the other surface of the transfer paper. A re-feeding unit having a transport path for transporting the transfer paper again from the rear of the apparatus main body to the printing unit through the lower portion, and a re-feeding unit provided in the re-feeding unit, wherein the printing unit re-prints the transfer paper. A reversing mechanism for reversing before transferring the paper to the printer, and a paper discharge unit for switching the transfer paper having the image transferred to one side thereof to be discharged to one of the discharge port and the re-feeding unit. The re-feeding unit located below the apparatus main body An image forming apparatus characterized in that an optional sheet feeding unit can be attached to a lower surface of the image forming apparatus. 2. A transport path for transporting transfer paper from the optional paper feed unit to the printing unit is provided in the re-feed unit located below the apparatus main body in a substantially vertical direction. The image forming apparatus according to claim 1, wherein: 3. The apparatus according to claim 1, wherein the sheet re-feeding unit and the optional sheet feeding unit located below the apparatus main body can be pulled out to the front side of the apparatus main body. The image forming apparatus as described in the above. 4. The image forming apparatus according to claim 3, wherein said reversing mechanism is provided in said sheet re-feeding section located below said apparatus main body.