JP3514169B2 - Print medium reversing device for image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print medium reversing device for an image forming apparatus such as a laser printer capable of double-sided printing.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view of a conventional image forming apparatus capable of double-sided printing. The configuration and operation of the conventional technique will be described below with reference to FIG.

As shown in FIG. 6, a conventional image forming apparatus capable of double-sided printing includes an electrophotographic laser printer main body 101, a laser unit 102, a photosensitive drum 103,
Developing roller 104, toner 105, transfer device 108, heating type fixing device 109, print medium supply cassette 110,
Print medium supply device 111, print medium discharge tray 112,
Print medium reversing unit 113, print medium transport path switching device 11
4, and a conveyance roller 1 for conveying the print medium 115
16a to 116f and the like.

In the image forming apparatus having the above structure, an image is written on the photosensitive drum 103 by the laser unit 102, and the toner 105 is supplied from the developing roller 104 to the photosensitive drum 103. Print medium supply cassette 11
The print medium 115 in 0 is supplied into the laser printer main body 101 by the print medium supply device 111, and is conveyed in the arrow X direction by the conveyance rollers 116a and 116b in the print medium conveyance path 117a. The toner on the photosensitive drum 103 is transferred to the print medium 115 by the transfer device 108,
Further, in the case of single-sided printing after being fixed by the fixing device 109, the conveyance roller 116c passes through the print medium conveyance path switching device 114 and the print medium conveyance path 117b, and then the conveyance roller 116c.
The sheet is discharged to the print medium discharge tray 112 by d.

In the case of double-sided printing, the print medium 1 after front surface printing
15 is conveyed to the left in FIG. 6 (on the side of the print medium conveyance path 117c) by the conveyance roller 116c by the conveyance path switching of the print medium conveyance path switching device 114, and is sent to the print medium reversing unit 113. Print medium 1 sent to print medium reversing unit 113
The sheet 15 once enters the switchback conveyance path 122, is turned upside down by the reverse rotation of the conveyance roller 116e, and is sent out to the print medium conveyance path 117d. A cooling fan 123 is provided in the vicinity of the print medium conveyance path 117d, and the print medium 115 is cooled there, and then the print medium conveyance path 117 is provided.
e 117 f, and again the laser printer main body 1
01, and a toner image is printed on the back surface of the print medium 115. The print medium 115 passes through the fixing device 109 and the print medium conveyance path switching device 114, and then the print medium discharge tray 112.
It is discharged to.

[0006]

In the above-mentioned image forming apparatus of the heat fixing system, the temperature of the print medium 115 after fixing is 120 ° C. or more by fixing, so that the water content of the print medium 115 after surface printing is lowered. During double-sided printing, the transfer device 108 is again entered in this state. In order to obtain high image quality, it is necessary that the print medium 115 is sufficiently cooled and the water content of the print medium 115 is recovered. However, the temperature after the surface printing is high and the water content is lowered.
Is unsuitable as a transfer condition when printing on the back side,
The print quality on the back side deteriorates.

When the image forming apparatus changes from monochrome to color, the toner layer to be transferred becomes four layers, and this problem becomes more remarkable. Further, when it is attempted to design the image forming apparatus at high speed and compactly, it becomes difficult to recover the temperature and the water content of the print medium, and this problem becomes more remarkable.

The present invention solves the above-mentioned conventional problems, and in a heat fixing type image forming apparatus, a compact image forming apparatus which can quickly cool the printing medium after the surface printing and recover the water content is provided. It is an object of the present invention to provide a print medium reversing device for use in printing.

[0009]

In order to solve the above-mentioned problems, the present invention provides a first printing method in which a print medium is inverted to a switchback transport path or to a switchback transport path.
Inverted by media transport path or switchback transport path
Second print medium for transporting the printed print medium to the image forming apparatus
Adjacent to one of the transport paths,
By providing a ventilation path for each of the transport paths and a fan for sucking the outside air in the same ventilation path, the outside air containing moisture is sucked from this ventilation path, and the print medium of the print medium is printed between the front side printing and the back side printing. It becomes possible to effectively cool and recover the water content, and it is possible to provide a compact print medium reversing device for an image forming apparatus which can obtain high print quality in double-sided printing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a first print medium conveyance path for conveying a print medium image-formed by an image forming apparatus to a switchback conveyance path, and the switchback. an image forming apparatus for printing medium reversing device including a second print media transport path for transporting the print medium that has been inverted by the conveyance path to the image forming apparatus, conveyance path or the first of the switchback Print
Izu of medium transport path or the second print media transport path
Printing for an image forming apparatus characterized in that some of the transport paths are adjacent to each other, an air passage is provided in each of the adjacent transport paths, and a fan that sucks outside air is further provided in the ventilation path. is obtained by a medium reversing device, the switch back transportation path or the first print medium conveying path or the second print media transport path
The air passage and the fan respectively provided in any one of the conveyance paths can efficiently cool the printing medium after the surface printing and recover the water content, and obtain high double-sided printing quality.

According to a second aspect of the present invention, the fan is
The print medium reversing device for an image forming apparatus according to claim 1, wherein the print medium reversing device is provided on the outer wall side of the first or second print medium transport path and the switchback transport path. It is possible to directly suck the contained outside air into the print medium reversing device.

According to a third aspect of the present invention, the fan is
The print medium reversing device for an image forming apparatus according to claim 1, wherein the print medium reversing device is provided between the first or second print medium transport path and the switchback transport path.
The outside air can be blown directly to the non-printing surface (the back surface, which is the next printing surface) side of the printing medium in the first or second printing medium conveying path, and sufficient moisture content recovery is possible. .

According to a fourth aspect of the present invention, the fan is
The print medium reversing device for an image forming apparatus according to claim 1, wherein the print medium reversing apparatus is provided on the image forming apparatus side from the first or second print medium conveying path and the switchback conveying path. Can be sufficiently sucked into the print medium reversing device along the ventilation path.

According to a fifth aspect of the present invention, the first substantially U extending from the switchback transport path to the second print medium transport path is provided.
A character-shaped conveying path is provided, and a length from the ventilation path to the ventilation path through the switchback conveying path, the first substantially U-shaped conveying path and the second print medium conveying path is the length of the print medium. The above is the print medium reversing device for an image forming apparatus according to any one of claims 1 to 4, wherein the print medium is transferred while passing through the first substantially U-shaped conveyance path. The back end of the print medium is cooled without blocking the air flow of the fan.

According to a sixth aspect of the present invention, a second substantially U extending from the first print medium conveyance path to the switchback conveyance path is provided.
A character-shaped transport path is provided, and the length from the ventilation path to the ventilation path through the first print medium transport path, the second substantially U-shaped transport path and the switchback transport path is the length of the print medium. The above is the print medium reversing device for an image forming apparatus according to any one of claims 1 to 5, wherein the print medium is transferred while passing through the second substantially U-shaped conveyance path. The back end of the print medium is cooled without blocking the air flow of the fan.

FIG. 1 shows an embodiment of the present invention.
It will be described with reference to FIG.

FIG. 1 is a vertical sectional view of the entire image forming apparatus according to an embodiment of the present invention.

As shown in FIG. 1, an image forming apparatus according to an embodiment of the present invention is an electrophotographic color printer 1 as a main body of an image forming apparatus capable of printing A3 size, a laser unit 2, a photosensitive drum. 3, developing roller 4, toner 5 arranged in parallel for each of the four colors, intermediate transfer belt 6, first transfer device 7 corresponding to each color, second transfer device 8, heating fixing device 9, print medium supply Cassette 1
0, print medium supply device 11, print medium discharge tray 12,
It is composed of a removable print medium reversing device 13, a print medium transport path switching device 14, transport rollers 16a and 16b for transporting the print medium 15, and the like.

The print medium 15 may be of A3 size, but in this embodiment, the most frequently used A4 size print medium (letter size print medium in the United States) is fed laterally. In this case (the long side is the leading end and the trailing end in the carrying direction), the purpose is to obtain the highest effect, and an example of A4 transverse feeding will be described.

In the image forming apparatus having the above structure, an image is written on the photosensitive drum 3 by the laser unit 2, and the toner 5 is supplied to the photosensitive drum 3 from the developing roller 4 for each color. When the intermediate transfer belt 6 rotates in the direction of arrow A, the toner 5 of each color is transferred onto the intermediate transfer belt 6 by the first transfer device 7. Print medium supply cassette 10
The print medium 15 is supplied to the color printer 1 by the print medium supply device 11, and the print medium conveying path 17 as a part of the first print medium conveying path is formed by the conveying roller 16a.
A is conveyed in the direction of arrow B. The toner 5 on the intermediate transfer belt 6 is transferred to the print medium 15 by the second transfer device 8 and further fixed by the fixing device 9, and in the case of single-sided printing,
Print medium transport path 1 as part of the first print medium transport path
7b, transport roller 16b to print medium transport path switching device 1
4 and is discharged to the print medium discharge tray 12 by the conveyance roller 16b.

In the case of double-sided printing, the print medium 1 after front surface printing
5 is conveyed to the left side of FIG. 1 (on the side of the print medium conveyance path 17c) by the conveyance path switching of the print medium conveyance path switching device 14, and enters the print medium reversing device 13 from the print medium conveyance path 17c via the print medium conveyance path 17d. The details of the print medium reversing device 13 will be described later, but here, the print medium 15 is turned upside down, conveyed again into the color printer 1, and the toner 5 transferred to the intermediate transfer belt 6 with the same contents as described above is transferred to the second side. Printing is performed on the back surface of the print medium 15 by the transfer device 8. The print medium 15 is discharged to the print medium discharge tray 12 via the fixing device 9 and the print medium conveying path switching device 14.

Next, the construction and operation of the print medium reversing device 13 will be described with reference to FIGS. FIG. 2 is a detailed cross-sectional view of the print medium reversing device shown in FIG. 1, showing a state in which the print medium is at the lowermost end of the switchback transport path,
FIG. 3 is a detailed cross-sectional view of the print medium reversing device shown in FIG. 1, showing a state in which the print medium is passing through a substantially U-shaped conveyance path.

As shown in the figure, the print medium reversing device 13
Is a print medium transport path 17d connected to the print medium transport path 17c of the print medium transport path 17b of the color printer 1, and the print medium transport path 17d transports the print medium 15 from the print medium transport path 17d to the switchback transport path 22. The print medium transport path 17e as a part of the first print medium transport path and the print medium 15 reversed by the switchback transport path 22 to guide the print medium 15 into the color printer 1 again. The print medium transport path 17f configured to have a substantially U shape for transporting to the medium transport path 17g is provided, and the switchback transport path 22 and the print medium transport path 17g are adjacent to each other so that their cross sections are substantially parallel. Is configured as. Further, a ventilation hole 24 is provided as a ventilation path that penetrates the switchback transport path 22 and the print medium transport path 17g, and further penetrates the print medium transport path 17e to escape upward. A fan 23 for sucking outside air is provided on the outer wall side.

At this time, the length from the ventilation hole 24 to the ventilation hole 24 through the switchback transport path 22, the print medium transport path 17f and the print medium transport path 17g is from the front end to the rear end of the recording medium 15 in the transport direction. It is formed so as to be longer than the length. That is, as shown in FIG. 3, the print medium 15 is bent along the U-shape of the print medium transport path 17f,
It is formed so that the front end and the rear end of the print medium 15 do not protrude into the vent hole 24 when the front end and the rear end of the print medium 15 are aligned at the same position.

The print medium 15 printed on the surface is the print medium transport path 17b of the print medium transport path 17b of the color printer 1.
It is conveyed to the print medium conveyance path 17d connected to c, and is sandwiched by the drive roller 18 and the driven roller 19a which are rotating in the direction of arrow C via the first print medium conveyance path 17e and is transferred to the switchback conveyance path 22. Be transported. The print surface of the print medium 15 reaching the switchback transport path 22 is cooled by the fan 23 provided on the ventilation hole 24.

The print medium 15 held in the switchback transport path 22 reaches the bottom end at the time when the reverse roller pair 2
1 is moved in a direction of holding the print medium 15 as indicated by an arrow D by a driving unit (not shown), and the print medium 15 is conveyed upward by rotation of the reversing roller pair 21. At this time, the reversing lever 2
0 rotates about the fulcrum, the front end of the print medium 15 is directed toward the print medium transport path 17f, and the print medium 15 is transported to the print medium transport path 17g by rotation of the reversing roller pair 21. The leading end of the print medium 15 has a driving roller 18 and a driven roller 19b.
And is conveyed in the direction of the print medium conveyance path 17g by these rollers, and the rear end of the print medium 15 is the reverse roller pair 2
Up to 1, the print surface of the print medium 15 is cooled by the fan 23.

Further, since the switchback transport path 22 and the print medium transport path 17g are adjacent to each other and are substantially parallel to each other, and the vent hole 24 penetrating the switchback transport path 22 and the print medium transport path 17g is provided. The wind of the fan 23 can cool both sides of the print medium 15 passing through the switchback transport path 22 and the print medium transport path 17g. Further, while the print medium 15 is passing through the print medium transport path 17f, the front end and the rear end of the print medium 15 do not pass each other in the ventilation hole 24 when the rear end of the print medium 15 passes in front of the fan 23. , The print medium 15 is the outlet 17h
By the time, the rear surface is cooled without blocking the wind of the fan 23 at the rear end of the print medium 15 itself. Thereby, the print medium 1 heated by the heating type fixing device 9
5 is transported to the color printer 1 again in a sufficiently cooled state.

Further, since the cooling effect of the print medium reversing device 13 is higher when the outside air is directly taken in, it is more effective to install the print medium reversing device 13 on the outermost side of the image forming apparatus as shown in FIG. Target.

FIG. 4 is a detailed sectional view of a printing medium reversing device showing another embodiment.

As shown in FIG. 4, the print medium conveying path 17b
Is adjacent to the switchback transport path 22 and the vent hole 24 penetrates through the print medium transport path 17b, printing is performed in order to prevent the front end and the rear end of the print medium 15 from passing each other in the vent hole 24. A substantially U-shaped transport path extending from the medium transport paths 17b and 17e to the switchback transport path 22 is provided, and a length from the vent hole 24 to the vent hole 24 via the print medium transport paths 17b and 17e and the switchback transport path 22 is set. The print medium 15 is formed to have a length equal to or longer than the length from the front end to the rear end of the print medium 15 in the transport direction.

FIG. 5 is a detailed sectional view of a printing medium reversing device showing another embodiment.

1 to 3, an ideal state in which the air from the fan 23 hits the print medium 15 sufficiently has been described, but in FIG. 5, the rear end of the print medium 15 partially blocks the front end of itself. Has become. Even in this case, the fan 2
The air flow sent in 3 goes around the lower part of the rear end of the print medium 15 so that the front end of the print medium 15 can be sufficiently cooled. Further, the fan 23, as shown in FIG.
It is also effective if it is installed on the right side of the print medium carrying path 17g (on the side of the image forming apparatus), or if it is installed between the switchback carrying path 22 and the print medium carrying path 17g.

In the above, the print medium conveying path 17e is formed above the print medium reversing device 13, and the print medium conveying path 1 is formed.
Although the configuration has been described in which the sheet is conveyed downward from 7e to the switchback conveyance path 22, the printing medium conveyance path 17e is formed in the lower part of the printing medium reversing device 13, and the printing medium conveyance path 17e is moved upward from the switchingback conveyance path 22. Obviously, it is also effective as a structure for transporting toward.

Although an example of an A3 size image forming apparatus has been described above, in the case of an A4 size image forming apparatus, the short side of the most frequently used A4 size printing medium is set at the front end and the rear end in the conveying direction. It is obvious that it is effective to have the above-mentioned configuration in the case of A4 vertical feeding as the end.

[0035]

According to the present invention, the following effects can be obtained.

(1) According to the first aspect of the invention, the outside air containing moisture is sucked in by the ventilation passage and the fan, so that the printing medium after surface printing can be efficiently cooled and the water content can be recovered. It is possible to obtain a compact print medium reversing device for an image forming apparatus that can obtain high double-sided printing quality.

(2) According to the second aspect of the present invention, it becomes possible to directly suck the outside air containing an appropriate amount of moisture into the inside of the print medium reversing device, so that the print medium can be cooled and the water content can be recovered more efficiently. To be done.

(3) According to the invention described in claim 3, the outside air can be blown directly to the non-printing surface (the back surface, which is the next printing surface) side of the printing medium in the printing medium conveying path,
Sufficient water content recovery is possible.

(4) According to the invention described in claim 4, the outside air can be sufficiently sucked into the print medium reversing device along the air passage, and the print medium can be cooled and the water content can be recovered more efficiently. Be seen.

(5) According to the fifth and sixth aspects of the present invention, the print medium does not block the wind of the fan at the rear end of itself while passing through the substantially U-shaped conveying path, and the back surface of the print medium is It will be cooled.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an entire image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a detailed cross-sectional view of the print medium reversing device shown in FIG. 1, showing a state in which the print medium is at the lowermost end of the switchback transport path.

FIG. 3 is a detailed cross-sectional view of the print medium reversing device shown in FIG. 1, showing a state in which the print medium is passing through a substantially U-shaped conveyance path.

FIG. 4 is a detailed cross-sectional view of a print medium reversing device according to another embodiment.

FIG. 5 is a detailed cross-sectional view of a print medium reversing device showing still another embodiment.

FIG. 6 is a sectional view of a conventional image forming apparatus capable of double-sided printing.

[Explanation of symbols]

1 color printer 2 laser unit 3 photoconductor drum 4 developing roller 5 toner 6 Central belt 7 First transfer device 8 Second transfer device 9 Fixing device 10 Print medium supply cassette 11 Print medium supply device 12 Print medium discharge tray 13 Print media reversing device 14 Print medium transport path switching device 15 print media 16 Conveyor rollers 17a to 17g Print medium conveyance path 18 Drive roller 19 Driven roller 20 Reversing lever 21 Reverse roller pair 22 Switchback transport path 23 fans 24 vents

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 2000-264494 (JP, A) JP 8-137371 (JP, A) JP 2000-75709 (JP, A) JP 2000-296970 (JP , A) JP 7-239647 (JP, A) JP 61-22375 (JP, A) JP 2000-281239 (JP, A) JP 2000-44131 (JP, A) JP 11- 212316 (JP, A) JP-A-1-242327 (JP, A) Actually opened 64-6441 (JP, U) Actually opened 62-190256 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/00 106 G03G 21/20 G03G 21/00 370-540

Claims (6)

(57) [Claims] 1. A first print medium conveyance path for conveying a print medium image-formed by an image forming apparatus to a switchback conveyance path for reversing the print medium, and a print medium reversed by the switchback conveyance path for the image. A print medium reversing device for an image forming apparatus, comprising a second print medium transport path for transporting the switchback transport path to the forming apparatus.
Alternatively, one of the first print medium transport path and the second print medium transport path may be adjacent to each other and may be adjacent to each other.
A print medium reversing device for an image forming apparatus, characterized in that an air passage is provided in each of the conveying passages, and a fan that sucks outside air is further provided in the air passage. 2. The print medium reversing device for an image forming apparatus according to claim 1, wherein the fan is provided on the outer wall side of the first or second print medium conveyance path and the switchback conveyance path. 3. The print medium reversing device for an image forming apparatus according to claim 1, wherein the fan is provided between the first or second print medium conveyance path and the switchback conveyance path. 4. The print medium for an image forming apparatus according to claim 1, wherein the fan is provided closer to the image forming apparatus than the first or second print medium conveying path and the switchback conveying path. Inversion device. 5. A first substantially U-shaped transport path extending from the switchback transport path to a second print medium transport path is provided, and the switchback transport path and the first substantially U-shaped transport path are provided from the ventilation path. The print medium for an image forming apparatus according to any one of claims 1 to 4, wherein a length from the path and the second print medium conveyance path to the ventilation path is equal to or longer than the length of the print medium. Inversion device. 6. A second substantially U-shaped transport path from the first print medium transport path to the switchback transport path is provided, and the first print medium transport path and the second substantially U path are provided from the ventilation path. The print medium for an image forming apparatus according to any one of claims 1 to 5, wherein a length from the character-shaped transport path and the switchback transport path to the ventilation path is equal to or more than a length of the print medium. Inversion device.