JP2001287873A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To significantly shorten the time for double printing a plurality of recording sheets to improve the printing efficiency. SOLUTION: In the double printing of recording sheets, the advancing recording material having a print on one side is waited in a reversion waiting position 29 where it never interferes with the carrying of the following recording material in a recording material reversing passage, and the printing of the reverse side of the advancing recording material is performed after one side of the following recording material is subjected to printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for printing a document or image created by a host apparatus on a recording medium, such as an ink jet printer, and more particularly, to the prevention of ink contamination and the printing efficiency when performing double-sided printing. It relates to the improvement of.

[0002]

2. Description of the Related Art For example, when print data sent from a host device is printed on recording paper by an ink jet printer,
Ink is ejected from nozzles of a recording head and adheres to recording paper to form characters and images. For this reason, immediately after printing, the ink adhering to the recording paper is not dried. Smear due to no ink occurs. In order to prevent the ink from being stained or the like, for example, as described in JP-A-5-32024 and JP-A-6-134982, the recording density for one-sided printing and the recording density for two-sided printing are set. In other words, the amount of ink adhering to the recording paper during double-sided printing can be reduced, or as described in Japanese Patent Application Laid-Open No. 6-134982, before printing on the front side of the recording paper, A standby time according to the type is provided, and the back side printing is performed after the standby time.

[0003]

However, when performing double-sided printing, the recording density is changed from that for single-sided printing, and the amount of ink adhering to the recording paper during double-sided printing is reduced. The image formed at the time is deteriorated.

Further, if a standby time is provided before printing on the front side of the recording paper and before moving to the back side printing, the standby time for each recording paper is accumulated when performing double-sided printing on a plurality of recording papers. However, the printing time becomes long, and the printing productivity is deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of improving the printing efficiency by remarkably reducing the time required for duplex printing on a plurality of recording papers. It is.

[0006]

SUMMARY OF THE INVENTION An image forming apparatus according to the present invention is an image forming apparatus capable of printing on both sides of a recording material. The recording material reversing path is retracted to a position where it does not interfere with the conveyance of the following recording material, and after printing on one side of the following recording material, printing is performed on the back surface of the preceding recording material.

A first transport path for transporting the single-sided printed recording material to the reversal standby position and a second transporting the recording material re-fed from the reversal standby position to the recording section in the recording material reversing path.
Transport path, a branch claw for switching between the first transport path and the second transport path, and transporting the recording material transported on the first transport path to the reversal standby position, and re-feeding the recording material from the reversal standby position. A switchback unit that conveys the recording material to the second conveyance path, conveys the preceding recording material on which one-side printing has been performed to the second conveyance path, holds the recording material, and retreats from the first conveyance path and the reversal standby position Good to let.

Further, it is desirable that a recording material holding section for bending and holding the preceding recording material is provided in the second transport path for retracting the preceding recording material.

Further, when sequentially printing images for each page on the front and back surfaces of a plurality of recording materials, an odd-numbered page is printed on the front surface of the preceding recording paper and the preceding recording paper. It is preferable to print an even-numbered page on the back surface of the following recording paper.

[0010] Further, when sequentially printing images for each page on the front and back surfaces of a plurality of recording materials, odd pages are printed on the front surfaces of the first and second recording sheets. To print an even-numbered page on the back of the first recording paper, print an even-numbered page on the back of the first recording paper, and then print an odd-numbered page on the third recording paper. The odd page is printed on the second recording sheet, the even page is printed on the back side of the second recording sheet, the even page is printed on the back side of the second recording sheet, and the fourth page is printed. Prints odd pages on a piece of recording paper,
It is preferable to repeat printing an odd-numbered page on the fourth recording sheet and then printing an even-numbered page on the back surface of the third recording sheet.

Further, the recording section for printing on the recording paper has an ink jet head mounted on a carriage which moves in the main scanning direction and ejecting ink from nozzles for printing.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet printer according to the present invention has a double-sided printing function, and includes a first side for conveying a single-sided printed recording material to a reversal standby position in a reversing path of the recording material when performing double-sided printing. A transport path, a second transport path for transporting the re-fed recording material from the reversal standby position to the recording unit, and a first transport path.
A branching claw for switching between the first conveyance path and the second conveyance path, conveying the recording material conveyed on the first conveyance path to the reversal standby position, and conveying the recording material re-fed from the reversal standby position to the second conveyance path It has switchback means for transporting to a road.

With this ink jet printer, for example, the first page is printed on the front side of the first recording sheet, the second page is printed on the back side, the third page is printed on the front side of the second recording sheet, and the back side is printed. When the fourth page is printed, the fifth page is printed on the front side of the third recording paper, and the sixth page is printed on the back side, first, the recording unit prints the first page on the front side of the first recording sheet. The page is printed, discharged to the reversal standby position, fed again by the switchback means, sent to the second transport path, held on the second transport path, and moved from the first transport path and the reversal standby position. Evacuate. Next, the second sheet of recording paper is fed from the sheet cassette, the third page is printed on the surface of the second sheet of recording paper, and is discharged to the reversal standby position. Thereafter, the first sheet of recording paper printed on the front side is sent to the recording unit, the second page is printed on the back side, and the recording sheet on which the first and second pages are printed on the front and back sides is passed through a discharge path. Discharge to the output tray. At a certain timing from when the conveyance of the first recording sheet to the recording section is started, the second recording sheet discharged to the reversal standby position is sent to the second conveyance path and held. After printing the second page on the back side of the first sheet, the second sheet is sent from the second transport path to the printing unit, the fourth page is printed on the back side, and the third page is printed on the front and back sides. 2 which printed page 4 and page 4
The sheet of recording paper is discharged to a discharge tray. Thereafter, the fifth and sixth pages are printed on the front and back surfaces of the third recording sheet, and are discharged to a discharge tray.

[0014]

FIG. 1 is a perspective view showing an ink jet printer according to an embodiment of the present invention. As shown in the drawing, the ink jet printer 1 has a printing mechanism 2, a paper feed tray 3 capable of stacking a plurality of recording papers, a manual feed tray 4, and a paper discharge tray 5, and when print data is sent from a host device. ,
Based on the sent print data, the printing mechanism 2 records characters and images on recording paper sent from the paper feed tray 3 or the manual feed tray 4, and discharges them to the discharge tray 5.

As shown in FIG. 2, the printing mechanism 2 includes a carriage 8 slidably held in a main scanning direction by a main guide rod 6 and a sub guide rod 7, and a carriage 8.
And a recording head 9 having a plurality of nozzles for ejecting ink droplets of each color of yellow Y, cyan C, magenta M, and black Bk, and a recording head detachably provided on an upper portion of the carriage 8 for each color. 9 has four color ink tanks 10 for supplying ink. The ink tank 10 mounted on the carriage 8 is held by a holding lever 11.

At a position facing the nozzle surface of the recording head 9 having a plurality of nozzles, a conveying roller 13 is used to convey the recording paper 12 to be printed by the recording head 9 in the sub-scanning direction.
And the recording paper 12
Is provided, and has a print receiving member 16 with the transport belt 15 interposed therebetween. The transport roller 13 has a diameter that ensures the adhesion of the recording paper 12 during double-sided printing and does not separate the curvature, for example, at least 30 mm.
mm, and a medium resistance body having a volume resistance of 10 ⁸ Ωcm to 10 ¹² Ωcm is preferably used as the transport belt 15. A tip roller 17 for defining a feed angle of the recording paper 12 is pressed against the transport roller 13 via a transport belt 15.

Further, in order to feed the recording paper 12 from the paper feed cassette 3 onto the transport belt 15, the paper feed roller 18 and the friction pad 1 that separate and feed the recording paper 12 one by one are provided.
9 and a guide member 21 for guiding the fed recording paper 12 to the transport roller 13 and the intermediate roller 20. In order to feed the recording paper 12 from the manual tray 4 to the transport belt 15, a pickup roller 22 that picks up the recording paper from the manual tray 4, a feed roller pair 23 that feeds the recording paper, and an intermediate roller And a guide member 24 for guiding up to 20.

A guide member 2 for guiding the recording paper 12 is provided on a discharge path for discharging the printed recording paper 12 to the discharge tray 5.
And a discharge roller pair 26 for sending the recording paper 12 to the discharge tray 5. In addition, recording paper 1 is used to perform duplex printing.
The guide member 2 guides the recording paper 12 passing through the print position by the recording head 9 obliquely downward between the paper discharge tray 5 and the paper feed cassette 3 along a reversing path for reversing the recording paper 9.
Near the entrance of the guide member 27 and the guide member 25 on the sheet discharge side, a first branching claw 28 for branching the conveyance path of the recording paper 12 is provided so as to be swingable. A pair of switchback rollers 30 for discharging the recording paper 12 to the reversal standby position 29 on the upper surface of the paper feed cassette 3 and re-feeding the recording paper 12 from the reversal standby position 29 is provided near the end of the guide member 27. . The switchback roller pair 30 rotates forward when the recording paper 12 having been printed on one side is conveyed to the reversal standby position 29, and the recording paper 1
The sheet is stopped at a predetermined timing in order to clamp the rear end of the sheet No. 2 in the discharge direction. Guide member 27 and switchback roller pair 30
A second branching claw 31 is provided between the second branch claws 31 for switching between a transport path for transporting the recording paper 12 to the reversal standby position 29 and a transport path for re-feeding the recording paper 12 from the reversal standby position 29. A conveyance path for feeding the recording paper 12 re-fed by the switchback roller pair 30 to the conveyance belt 15 includes a guide member 32 for guiding the recording paper 12, a pair of double-sided relay rollers 33 for conveying the recording paper 12, and A driven roller 34 that feeds the recording paper 12 to the intermediate roller 20 by following the transport roller 13
Having.

When performing double-sided printing with the ink jet printer 1 configured as described above, as shown in FIG.
The branching claw 28 is turned upward to switch to the duplex printing side, and the second branching claw 31 is turned to the guide member 32 side to switch to the discharge side with respect to the reversal standby position 29. Then, characters and images are printed by the recording head 9 on the surface of the recording paper 12 transported by the transport belt 15 from the paper feed cassette 3. The printed recording paper 12 is sent from the first branch claw 28 to the guide member 27, the switchback roller pair 30 is rotated forward to discharge the recording paper 12 to the reversal standby position 29, and the switchback roller pair 30 is moved at a predetermined timing. The recording paper 12 is stopped and the rear end of the recording paper 12 in the discharging direction is clamped. Thereafter, as shown in FIG. 4, the second branch pawl 31 is rotated upward to close the discharge path of the recording paper 12, and
The transport path for feeding the re-fed recording paper 12 is opened.
Then, the switchback roller pair 30 is reversed, and the recording paper 12 discharged to the reversal standby position 29 is sent to the duplex roller pair 33 while being guided by the guide member 32. When the recording paper 12 having the surface printed thereon is sent, the pair of double-sided relay rollers 33 is driven while grasping both ends of the recording paper 12 where the recording paper 12 is not printed, and conveys the recording paper 12, and the leading end of the recording paper 12 is driven. Before reaching the rollers 34, the driving of the duplex relay roller pair 33 is performed by a drive on / off means such as an electromagnetic clutch at the timing when the rear end of the recording paper 12 is disengaged from the switchback roller pair 30 and passes through the position of the second branching pawl 31. To stop the rotation. Then, when a predetermined time that has been predetermined according to the time for printing one surface of the recording paper 12 elapses,
The two-sided relay roller pair 33 is driven, and the recording paper 12 printed on the front surface is sent from the driven roller 34 to the transport belt 15. Also,
The first branching claw 28 provided on the discharge side of the recording head 9 is rotated downward to open a discharge path for discharging to the discharge tray 5. In this state, the recording paper 12 sent to the conveyance belt 15 is conveyed to the position of the recording head 9, and characters and images are printed on the back surface by ink ejected from the recording head 9. The recording paper 12 printed on the front and back sides is discharged to the discharge tray 5 through a discharge path.

Next, the operation of the inkjet printer 1 for printing on both sides of a plurality of recording papers 12 will be described. For example, the first page is printed on the front side of the first recording paper 12a, the second page is printed on the back side, the third page is printed on the front side of the second recording paper 12b, and the fourth page is printed on the back side. When printing and printing the fifth page on the front surface of the third recording paper 12c and printing the sixth page on the back surface, first print the first page on the front surface of the recording paper 12a, and Then, the sheet is re-fed and fed to the pair of double-sided relay rollers 33 while being guided by the second branching pawl 31 and the guide member 32 as shown in FIG. The pair of double-sided relay rollers 33 conveys the fed recording paper 12, and before the leading end of the recording paper 12 a reaches the driven roller 34, the rear end of the recording paper 12 a is disengaged from the switchback roller pair 30, and the second branch is made. The rotation is stopped at the timing of passing the position of the claw 31, and the recording paper 12a is made to stand by in the transport path having the pair of double-sided relay rollers 33. Therefore, the first recording paper 12 can be made to stand by avoiding the discharge path for the printing position of the second recording paper 12b and the reversal standby position 29.

In this state, the second recording paper 12b is fed from the paper supply cassette 3, and the third page is printed on the surface of the recording paper 12b by the recording head 9, and as shown in FIG. Discharge to position 29. The recording paper 12b is in the reversal standby position 2
9, the recording paper 12b is gripped by the switchback roller pair 30, and the switchback roller pair 30 stops. Then, when a predetermined time elapses in accordance with the time for printing one surface of the recording paper 12,
As shown in FIG. 6, the two-sided relay roller pair 33 is driven, the recording paper 12a printed on the front surface is sent from the driven roller 34 to the conveyor belt 15, and the second page is printed on the back surface by the recording head 9, and The recording paper 12 a on which the first and second pages are printed on the back surface is discharged to the discharge tray 5 through a discharge path. The first recording paper 12a is transferred to the pair of double-sided relay rollers 33.
At a certain timing from the start of the conveyance by driving the second branch pawl 31, the second branching pawl 31 is rotated upward to open the conveyance path for feeding the recording paper 12b to be re-fed, and the switchback roller pair is opened. The recording paper 12b discharged to the reversal standby position 29 is sent to and held by the pair of double-sided relay rollers 33 while being guided by the guide member 32. After a lapse of a predetermined period of time after the printing of the second page has been completed on the back surface of the first recording paper 12a, the two-sided relay roller pair 33 is driven to send the recording paper 12b to the transport belt 15, and the recording head 9 Then, the recording paper 12b having the fourth page printed thereon and the third and fourth pages printed on the front and back sides is discharged to the discharge tray 5. afterwards,
The fifth and sixth pages are printed on the front and back surfaces of the third recording paper 12 c and are discharged to the discharge tray 5.

As described above, after printing the first page on the surface of the first recording paper 12a, the second recording paper 12b is immediately placed in a standby time while the ink attached to the surface of the recording paper 12a is dried. Since the third page is printed, the printing can be continuously performed without the waiting time until the ink dries, and the printing efficiency can be improved.

In the above embodiment, the fourth page is printed on the back of the second recording paper 12b immediately after the printing of the second page is completed on the back of the first recording paper 12a. The second recording paper 12 is formed by the duplex roller pair 33.
When the printing of the second page on the back side of the first recording paper 12a is completed in the state of holding the recording paper b, the third recording paper 12c is subsequently fed from the paper feed cassette 3 to perform the third recording. The fifth page is printed on the surface of the paper 12c,
The fourth page may be printed on the back surface of the second recording paper 12b after the printing of the fifth page is completed on the front surface of the sheet c. In this manner, the second page is printed on the back of the first recording paper 12a, the fifth page is printed on the front of the third recording paper 12c, and then the fourth page is printed on the back of the second recording paper 12b. By printing the page, the drying time of the ink adhered to the recording paper 12b can be made longer, and the recording paper 1b can be dried.
2 can be reliably prevented from being stained by ink.

In the above embodiment, the driven roller 3 passes from the second branch pawl 31 through the guide member 32 and the pair of double-sided relay rollers 33.
4 has been described, but as shown in FIG. 7, a pair of conveying rollers 35 is provided upstream of the pair of double-sided relay rollers 33, and the pair of conveying rollers 35 and the pair of double-sided relay rollers 33 are provided. By providing the guide plate 36 having a slack portion in the transport path between the two, the distance from the second branching pawl 31 to the driven roller 34 when the recording paper 12 printed on the surface by the two-sided relay roller pair 33 is held. The length of the recording paper 12 can be made shorter than the length of one sheet, and the size of the ink jet printer 1 can be reduced.

In each of the above embodiments, the ink jet printer 1
However, the present invention can be similarly applied to a copier and a facsimile of an ink jet ejection system or a printer, a copier and a facsimile of an electrophotographic system.

[0026]

As described above, according to the present invention, when performing double-sided printing on a recording material, a position where the preceding recording material on which single-sided printing is performed does not interfere with the conveyance of the succeeding recording material on the recording material reversing path. After printing on one side of the following recording material, and then printing on the back side of the preceding recording material,
Printing can be continuously performed on a plurality of recording materials, and the printing time when performing double-sided printing on a plurality of recording materials can be significantly reduced.

The recording material reversing path includes a first conveyance path for conveying the recording material printed on one side to a reversal standby position, and a second conveyance path for conveying the recording material re-fed from the reversal standby position to a recording unit. And a branch claw for switching between the first and second conveyance paths, and a recording material conveyed on the first conveyance path is conveyed to a reversal standby position, and is fed again from the reversal standby position. A switchback means for transporting the recording material to the second transport path, and transporting and holding the single-side printed preceding recording material to the second transport path. , And can be printed on one side of the succeeding recording material following the one-sided printing of the preceding recording material.
In addition, after printing on one side of the preceding recording material, while printing on one side of the succeeding recording material, the preceding recording material is held in the second conveyance path, so when printing by the ink jetting method, It is possible to sufficiently secure the drying time of the ink attached to the recording material, and it is possible to prevent the recording material printed on both sides from being stained by the ink.

Further, by providing a recording material holding section for bending and holding the preceding recording material in the second feeding path for retracting the preceding recording material, the length of the second feeding path can be shortened, and the image forming apparatus can be used. The body can be made compact.

When sequentially printing images for each page on the front and back surfaces of a plurality of recording materials, an odd-numbered page is printed on the front surface of the preceding recording paper and the preceding recording paper, and then the preceding recording paper is printed. By printing the even-numbered pages on the back side of the following recording paper, it is possible to eliminate the printing waiting time and print efficiently, and when printing by the ink jet method, the printing paper adheres to the recording material for printing. It is possible to sufficiently secure the drying time of the ink.

Further, when sequentially printing images for each page on the front and back surfaces of a plurality of recording materials, odd pages are printed on the front surfaces of the first recording paper and the second recording paper. To print an even-numbered page on the back of the first recording paper, print an even-numbered page on the back of the first recording paper, and then print an odd-numbered page on the third recording paper. The odd page is printed on the second recording sheet, the even page is printed on the back side of the second recording sheet, the even page is printed on the back side of the second recording sheet, and the fourth page is printed. The odd numbered page is printed on the fourth recording sheet, and the third page is printed on the fourth recording sheet.
By repeating printing even-numbered pages on the back side of the sheet of recording paper, printing can be performed efficiently without the need to wait for printing. The drying time of the attached ink can be more sufficiently secured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an ink jet printer according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of the ink jet printer.

FIG. 3 is an operation explanatory diagram showing a state in which the first recording sheet on which single-sided printing is performed is discharged to a reversal standby position when performing double-sided printing.

FIG. 4 is an operation explanatory diagram illustrating a state in which a first recording sheet on which single-side printing is performed is retracted when performing double-sided printing.

FIG. 5 is an operation explanatory view showing a state in which a first recording sheet printed on one side is retracted, and a second recording sheet printed on one side is discharged to a reversal standby position.

FIG. 6 is an operation explanatory diagram illustrating a state in which printing is performed on the back surface of the first recording sheet on which single-side printing has been performed.

FIG. 7 is another configuration diagram of a conveyance path for retracting a recording sheet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Ink jet printer, 2; Printing mechanism part, 3; Paper feed tray, 8; Carriage, 9; Recording head, 10; Ink tank, 12; Recording paper, 13; 28; first branch claw, 2
9: reversal standby position, 30; switchback roller pair, 3
1; second branch claw 32; guide member 33; double-sided relay roller pair 34;

Claims (6)

[Claims] In an image forming apparatus capable of printing on both sides of a recording material, when performing double-sided printing on a recording material, a preceding recording material on which single-sided printing has been performed is a recording material reversing path that follows a recording material that follows. An image forming apparatus, wherein the image forming apparatus is evacuated to a position where it does not interfere with conveyance, prints on one surface of a succeeding recording material, and then prints on the back surface of a preceding recording material. 2. A first conveying path for conveying a recording material printed on one side to a reversal standby position in the recording material reversing path, and a second conveying path for conveying a recording material re-fed from the reversal standby position to a recording unit. Transport path, a branch claw for switching between the first transport path and the second transport path, and transporting the recording material transported on the first transport path to the reversal standby position, and re-feeding the recording material from the reversal standby position. A switchback unit that conveys the recording material to the second conveyance path,
The image forming apparatus according to claim 1, wherein the preceding recording material on which one-side printing has been performed is transported to the second transport path, held and retracted from the first transport path and the reversal standby position. 3. The image forming apparatus according to claim 1, further comprising a recording material holding section for bending and holding the preceding recording material in the second conveyance path for retracting the preceding recording material. 4. An image forming apparatus according to claim 1, wherein when printing an image for each page on the front and back surfaces of a plurality of recording materials, a preceding recording paper and a following recording paper are printed. An odd-numbered page is printed on the front side of the recording sheet, and then an even-numbered page is printed on the back side of the preceding recording sheet and the succeeding recording sheet. 5. The image forming apparatus according to claim 1, wherein when printing an image for each page on the front and back surfaces of a plurality of recording materials sequentially, a first recording paper and a second recording paper are used. Odd pages are printed on the front side of the first recording sheet, even pages are printed on the back side of the first recording sheet, and even pages are printed on the back side of the first recording sheet. The odd-numbered pages are printed on the third sheet of paper, the odd-numbered pages are printed on the third sheet of paper, and then the even-numbered pages are printed on the back of the second sheet of paper. After printing the even-numbered pages on the back of the printer, print the odd-numbered pages on the fourth printing paper, print the odd-numbered pages on the fourth printing paper, and then print the even-numbered pages on the back of the third printing paper. An image forming apparatus, which repeats printing a page. 6. The ink-jet head according to claim 1, wherein a recording unit for printing on recording paper is mounted on a carriage that moves in a main scanning direction, and prints by ejecting ink from nozzles. An image forming apparatus comprising: