JPH043784A - Printer - Google Patents

Abstract

PURPOSE:To surely perform duplex printing with a simple structure by arranging a pair of conveying rollers on the sheet guide side of a reverse passage, providing one of a pair of conveying rollers on the sheet discharge side of the reverse passage, and arranging the other conveying roller on this conveying roller. CONSTITUTION:For duplex printing, the toner image transferred on a sheet is fixed on the sheet by a fixing unit 10, the sheet is guided to a descent passage 29 by a direction switching member 28, and the sheet is bitten by conveying rollers 30A, 30B and guided into a reverse passage 17A. When the rear end of the sheet exceeds the rollers 30A, 30B, the rear end of the sheet is guided in the direction of a conveying roller 30C along the rotating direction of the roller 30B by a coupling piece 31 protruded outward from the outer periphery of the roller 30B by a spring member 33, and the rear end of the sheet is bitten between the rollers 30B, 30C. The rear end of the sheet is guided into the second sheet passage 19A of a duplex printing unit 16A, and sheet is fed to a printing section 2 via the sheet passage 26 of the sheet feed cassette 11A.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printer, and particularly to a printer for double-sided printing that can print on both sides of a sheet of paper.

[Conventional technology]

First, a conventional printer capable of printing on both sides will be explained with reference to FIG.

The printer shown in FIG. 5 is an electrophotographic printer, and a printing section 2 is disposed in the center of the printer body 1. The printing unit 2 has a photosensitive drum 3 which is rotatably disposed as an image carrier holding an electrostatic latent image. 3, a charger 4 that uniformly charges the photosensitive drum 3, and an LED as an optical writing member that forms an electrostatic latent image on the uniformly charged photosensitive drum 3.
A head 5, a developing device 6 that visualizes this electrostatic latent image with toner to form a toner image, a transfer device 7 that transfers the toner image onto paper, a cleaner 8 that removes residual toner on the photosensitive drum 3, and the like are arranged. It is set up.

Inside the printer main body 1, there is a first paper path 9 that extends horizontally and supplies paper between the photosensitive drum 3 and the transfer device 7.
A fixing device 10 faces the first paper path 9 on the downstream side of the printing section 2 and fixes the toner image transferred to the paper onto the paper using heat and pressure.

Further, a paper feed cassette 11 is attached to the printer main body 1 on the extension of the first paper path 9 on the upstream side of the printing section 2, and the paper feed cassette 11 is stacked and stored. A supply roller 12 is disposed within the printer main body 1 for supplying sheets of paper to the first paper path 9 one by one.

Furthermore, a pair of mutually connected conveyance rollers 13 , 13 are disposed in the first paper path 9 on the upstream side of the printing section 2 , and a pair of conveyance rollers 13 , 13 on the downstream side of the fixing device 10 are arranged. 1
A direction switching member 14 is disposed in the paper path 9, and a paper discharge tray 15 is attached to the printer main body 1 near the direction switching member 14.

A duplex printing unit 16 for inverting the paper and printing on both sides of the paper is removably attached to the printer main body 1.
is the printer main body 1 via the direction switching member 14.
It has a horizontal reversing path 17 that can communicate with the first paper path 9 within.

A pair of transport rollers 518, 18 are disposed in the reversing passage 17, and these transport rollers 18, 18 are capable of transporting the paper supplied into the reversing passage 17 in either the left or right direction. Reversing passage 17 on the printer body 1 side
The transport roller 18.181! A second paper path 19 is connected thereto, which is a double-sided printing path for returning the paper reversely fed from If to the first paper path 9 on the upstream side of the printing section 2.

At the connection between the second paper path 19 and the reversing path 17,
A plurality of pairs of transport rollers 13, 13 are provided for transporting the paper from left to right in the figure, and this reversing path 17 opens above the duplex printing unit 16 at its most downstream position. There is.

Note that in the printer main body 1, the first paper path 9 is provided.
A third paper path 21 is formed which communicates with the upstream end of the second paper path 19 and the downstream end of the second paper path 19, respectively.

To perform double-sided printing using the above-described configuration, first, the topmost sheet of paper stored in the paper feed cassette 11 attached to the printer main body 1 is moved to the first paper path by the drive of the supply roller 12. 9 and is arranged in the first paper path 9 upstream of the printing section 2.
3, and conveyed in the first paper path 9 from right to left in the figure.

On the other hand, a toner image corresponding to the print information is sequentially formed on the photosensitive drum 3 of the printing section in synchronization with the conveyance of the paper, and the toner image is transferred to the photosensitive drum 3 and the transfer device 7 by the action of the transfer device 7. are sequentially transferred onto the top surface of the paper passing through.

After that, the toner image transferred onto the paper is fixed on the paper by pressure and temperature when the paper passes through the fixing device 10,
Further, the paper is transferred to the second paper path 1 by the direction switching member 14.
9, and the direction switching member 20 causes the transport rollers 18,
18 and conveys the paper so as to take a position beyond the direction switching member 20 to the rear end of the paper.

When the trailing edge of the paper passes the direction switching member 20, the driving of the transport rollers 18, 18 is stopped, and the direction of the direction switching member 20 is switched to introduce the paper in the reversing path 17 into the second paper path 19. Then, the transport rollers 18.18 are driven in the opposite direction to introduce the paper in the reversing path 17 into the second paper path 19 from the rear end. Then, the plurality of pairs of transport rollers 13, 13 disposed in the second paper path 19 transport the paper, and the paper is transferred to the first paper path 9 again via the third paper path 21 in the printer main body 1.
to be introduced within. At this time, the back side of the paper, on which printing has not yet been performed, faces the photosensitive drum 3.

Therefore, the toner image corresponding to the print information formed on the photosensitive drum 3 is sequentially transferred onto the upwardly facing back surface of the paper by the action of the transfer device 7 in synchronization with the conveyance of this paper, and then the toner image corresponding to the print information formed on the photosensitive drum 3 is sequentially transferred onto the upwardly facing back surface of the paper. After being fixed on the paper, the paper being conveyed by the switched direction switching member 14 is ejected to the paper ejection tray 15.

In this way, printing can be performed on both sides of the paper.

[Problem to be solved by the invention]

However, in the conventional device described above, it is necessary to provide a direction switching member 20 in the reversing path 17 in order to reverse the paper, and it is also necessary to adjust the conveyance rollers 18 and 18 disposed in the reversing path 17. Since it has to be rotated in both opposite directions, the structure is complicated and costs are high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printer that overcomes the above-mentioned problems with the conventional printers, can perform double-sided printing reliably with a simple structure, and can be manufactured at low cost.

[Means to solve the problem]

In order to achieve the above-mentioned object, the printer according to the present invention has the following features:
In a printer having a reversing passage that introduces paper printed on one side in a printing section, and a double-sided printing passage that conveys the paper introduced into this reversing passage from its rear end to the printing section, the reversing passage includes: A pair of conveyance rollers for introducing the paper into a reversing passage are arranged on the paper introduction side, and one of the pair of conveyance rollers is arranged to face the paper discharge side of the reversing passage communicating with the double-sided printing passage. , is characterized in that, together with this conveyance roller, another conveyance roller is provided for introducing the paper into the duplex printing path.

[For production]

According to the printer of the present invention having the above-described configuration, by rotating the three transport rollers in a predetermined direction, the paper is first introduced into the reversing path from the paper introduction side, and the trailing edge of the paper passes through the transport rollers. Once over the paper, the trailing edge of the paper is guided to the paper ejection side along the outer periphery of the transport roller located in the center.
The paper is introduced into the double-sided printing path from its rear end by the two transport rollers on the paper discharge side.

〔Example〕

The present invention will be explained below with reference to embodiments shown in the drawings. Note that components that are the same as or correspond to those of the prior art described above are designated by reference numerals in the drawings, and their explanations will be omitted.

FIG. 1 and FIG. 2 show an embodiment of a printer capable of double-sided printing according to the present invention, and in this embodiment,
A paper feed unit 22 is arranged at the lowest level. Further, a double-sided printing unit 16A for double-sided printing is stacked on the paper feed unit 22, and a printer main body 1A is stacked on the double-sided printing unit 16A.

A cassette storage section 23 is formed in the lower part of the printer main body 1 on an acid base (not shown), and this cassette storage section 23 is opened to the outside from the right side in FIG. 1. The paper feed cassette 11A is housed in the cassette storage section 23 so that it can be inserted and removed from the right side in the figure.

The paper feed cassette 11A has a paper storage section 25 which is open at the top in the cassette main body 24, and in the cassette main body 24 in front of the paper storage section 25, there is a paper storage section 25 extending in the vertical direction. A paper path 26 is formed having dimensions that allow one sheet of paper to be inserted therethrough. The size of the paper that can be inserted into this paper path 26 is not limited to the size of the paper in this paper feed cassette 11A, but it is also possible to insert paper of larger size stored in other paper feed cassettes. ing.

Further, the lower end of the paper passage 26 is widened to facilitate the introduction of paper, while the upper end of the paper passage 26 is connected to the first paper passage 9 for supplying paper to the printing section 2. It is arranged at an angle in order to improve the introduction of the paper.

A paper discharge tray 15A is formed in a convex shape on the upper surface of the printer main body 1A. Further, a curved paper discharge passage 27 for discharging paper to the paper discharge tray 15A branches upward from the first paper passage 9 on the downstream side of the fixing device 10, and a curved paper discharge passage 27 for discharging the paper to the paper discharge tray 15A branches upward. A direction switching member 28 is disposed in the first paper path 9 so that the paper being conveyed through the first paper path 9 can be selectively introduced into the paper discharge path 27 .

In the first paper path 9 on the downstream side of the direction switching member 28,
A descending passage 29 is formed which communicates with the first paper passage 9 and allows the paper to descend, and the downstream end of this descending passage 29 opens laterally. A pair of transport rollers 30A and 30B are disposed outside the downstream end of the descending passage 29 for guiding the paper in the descending passage 29 to the outside of the descending passage 29. A reversing passage 17A extending upward is formed on the downstream side of the reversing passage 17A. The transport rows 530A and 30B move the paper to the reversing path 17.
In order to push diagonally upward in the A direction, the imaginary line segment connecting the axes is inclined, as shown in detail in FIG. The transport roller 30A is a driven roller that is in pressure contact with the transport roller 30B.

The reversing passage 17A extends to the lower end of the printer main body 1A below the conveying roller 30B, and the conveying roller 30C, which is a driven roller that conveys the paper in the reversing passage 17A downward, is driven by the conveying roller 30B, which is a driving roller. It is arranged so that it comes into pressure contact with the

By the way, the conveyance roller 30B is connected to the descending passage 29.
from the reversing path 17A by both conveyance rollers 30A and 30B.
A fourth
As shown in FIG. Δ, on the outer periphery of the conveyance roller 30B,
At least one (two in the figure) engagement piece 31 is attached along the outer periphery of the conveyance roller 30B to guide the trailing edge of the sheet toward the conveyance roller 30G.

Each engagement piece 31 is attached to a support bin 32 as shown in FIG. 4B.
The spring member 33 causes a smooth curved engagement surface 34 to protrude toward the outer circumferential side of the transport roller 30B, and engages with the trailing edge of the paper to move the paper in the direction of the transport roller 30C. It is designed to guide you. Note that each engagement piece 31 is connected to other conveyance rollers 30A, 30.
When it comes into contact with G, it resists the spring force of the spring member 33 and retreats inside the conveyance roller 30B.

In the double-sided printing unit 16A located below the printer main body 1A, there is a reversing passage 17 of the printer main body 1A.
A second paper passage 19A is formed as a double-sided printing passage for re-supplying the paper that has been reversed so as to advance from the rear end to the printing unit 2 of the printer main body 1A.

The upstream end of this second paper path 19A is communicated with the downstream end of the reversing path 17A when the printer main body 1A is installed above the duplex printing unit 16A, and the second paper path The intermediate portion 19A extends in the horizontal direction so that the paper can be transported by a plurality of pairs of transport rollers 13, 13.

Furthermore, in the front part of the double-sided printing unit 16A, there is a vertical paper path that communicates with the paper path 26 of the paper feed cassette IIA of the printer main body 1A when the printer main body 1A is installed above the double-sided printing unit 16A. 35
A downstream end of the second paper path 19A is communicated with this paper path 35, so that the paper is conveyed upward within the paper path 35.

In the paper feeding unit 22 located below the double-sided printing unit 16A, a cassette storage section 36 is formed on an elevator board (not shown), and this cassette storage section 36 is shown in FIG. It is opened to the outside from the right side. A large-capacity paper feed cassette 11 is housed in the cassette storage portion 36 so as to be freely inserted and removed from the right side in the figure.

In addition, a paper feed cassette 11 is provided in the paper feed unit 22.
A supply roller 12 is disposed for taking out sheets of paper stacked one by one in the paper feed unit 2.
2, another paper passage 37 is formed for introducing the paper taken out by the supply roller 12 into the paper passage 35 of the duplex printing unit 16A.

Incidentally, a cassette drawer portion 38 is formed in each of the main body 1A of the printer and the paper feed unit 22 in FIG.

Next, the operation of this embodiment having the above-described configuration will be explained.

To perform double-sided printing, first, the paper feed cassette 11 installed in the printer main body 1A or the paper feed unit 22 is
The uppermost one of the sheets is taken out by the drive of the supply roller 12, and the paper is taken out from the paper cassette 11 in the printer main body 1A.
Paper in the paper feed unit 22 is introduced directly into the first paper path 9, while paper in the paper feed unit 22 is introduced through the paper path 35 in the duplex printing unit 16A and the paper path 26 in the paper feed cassette 11A of the printer main body 1A. The paper is introduced into the first paper path 9 through the paper.

On the other hand, a toner image corresponding to the print information is sequentially formed on the photosensitive drum 3 of the printing section in synchronization with the conveyance of the paper, and the toner image is transferred to the photosensitive drum 3 and the transfer device 7 by the action of the transfer device 7. are sequentially transferred onto the top surface of the paper passing through. Thereafter, the toner image transferred onto the paper is fixed on the paper by pressure and temperature as the paper passes through the fixing device 10, and then the paper is introduced into the descending path 29 by the direction switching member 28 and further lowered. The paper is caught in the conveyance rollers 30A and 30B at the downstream end of the passage 29 and transferred to the reversing passage 17A.
to be introduced within.

When the rear end of the paper passes between the transport rollers 30A and 30B, the rear end of the paper is moved in the rotational direction of the transport roller 30B by an engagement piece 31 protruding outward from the outer periphery of the transport roller 30B by a spring member 33. Convey roller 30C along
direction, and finally the trailing edge of the paper is transferred to the conveyance roller 3.
Insert it between 0B and 3OC. Then, the paper is introduced from the rear end into the second paper path 19A of the duplex printing unit 16A, and from there it is introduced into the paper feed cassette 11 of the printer main body 1A.
The paper is again supplied to the printing section 2 of the first paper passage 9 via the paper passage 26 of A. At this time, the back side of the paper, on which printing has not yet been performed, faces the photosensitive drum 3.

Therefore, the toner image corresponding to the print information formed on the photosensitive drum 3 is sequentially transferred onto the upwardly facing back surface of the paper by the action of the transfer device 7 in synchronization with the conveyance of this paper, and then the toner image corresponding to the print information formed on the photosensitive drum 3 is sequentially transferred onto the upwardly facing back surface of the paper. After being fixed on the paper, the switched direction switching member 28 introduces the paper into the paper discharge path 27, from which the paper is discharged to the paper discharge tray 15A on the top surface of the printer main body 1A.

In this way, printing can be performed on both sides of the paper.

According to the embodiment described above, if the conveying roller 30B, which is a driving roller for introducing the paper into the reversing path 17A, is driven to rotate only in the counterclockwise direction, the paper is reversed and transferred to the printing unit 2.
Therefore, the motor that drives the conveyance roller 30B can be made inexpensive. Furthermore, two conveyance rollers 30A and 30G are attached to the conveyance roller 30B.
By pressing the paper into the reversing passage 17A from the descending passage 29 without providing a direction switching member, the paper is transferred to the second
The paper can be supplied to the paper path 19A.

On the other hand, the paper feed cassette 11 can be replaced at the front of the printer main body 1A and the paper feed unit 22, and since the paper ejection tray 15A is formed on the top surface of the printer main body 1, No members that require any operation are provided on the rear surface or both side surfaces of the printing unit 16A and paper feeding unit 22. Therefore, the only part that needs to be opened for installing the printer is the front side of the printer body 1, so a large space is not required for installing the printer. Also, paper feed power set 1
Since the paper path 26 is formed in the printer 1A itself, there is no need for a special paper path inside the printer body 1A, and even if it is possible to print with multiple types of paper, it is possible to downsize the printer with a simple configuration. becomes. Since the descending passage 29 is provided and the reversing passage 17A is arranged upright, the reversing operation can be performed reliably by the weight of the paper, and in this respect as well, the printer as a whole can be made smaller.

It should be noted that the present invention is not limited to the two embodiments described above, and can be well applied to printers that use insulating or magnetic image carriers, and can be modified in various ways as necessary. is possible.

(Effects of the Invention) As described above, the printer according to the present invention has an excellent effect in that the structure for reversing paper can be simplified and manufactured at low cost.

Upper body, 25--paper storage section, 26--paper path,
27... Paper discharge path, 30... Conveyance roller, 31...
・Engagement piece.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the printer according to the present invention, and FIG. 1 is a longitudinal side view of the printer, and FIG.
The figure is a perspective view of FIG. 1, FIG. 3 is an enlarged view of the conveyance roller of FIG. 1, FIGS. 4A and B are explanatory diagrams of the engagement piece of the conveyance roller of FIG. 3, and FIG. FIG. 2 is a vertical cross-sectional side view of the printer.

Claims (1)

[Claims] In a printer having a reversing passage that introduces paper printed on one side in a printing section, and a double-sided printing passage that conveys the paper introduced into this reversing passage from its rear end to the printing section, the reversing passage includes: A pair of conveyance rollers for introducing the paper into a reversing passage are arranged on the paper introduction side, and one of the pair of conveyance rollers is arranged to face the paper discharge side of the reversing passage communicating with the double-sided printing passage. , A printer characterized in that, together with this conveyance roller, another conveyance roller is provided for introducing paper into a duplex printing path.