JP3474149B2 - Inkjet printer and printing method using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer and a printing method using the same, and more particularly to a double-sided jet type inkjet printer.

[0002]

2. Description of the Related Art Conventionally, as an inkjet printer for high-speed printing, a double-sided ejection type inkjet head is used to print an odd number page and an even number page at the same time (for example, see Japanese Patent Laid-Open No. 10-34902). A print head that faces a paper conveyance path from a paper feed unit to a paper discharge unit to print on both sides of the paper almost at the same time (see, for example, Japanese Patent Laid-Open No. 3-256762), or a head for printing on the front surface of the paper. And a double-sided printing head for performing double-sided printing (for example, Japanese Patent Laid-Open No. 10-76).
No. 713) are known.

[0003]

However, such a conventional ink jet printer has a problem that the structure and control are complicated and the apparatus becomes large in size. The present invention has been made in view of such circumstances, and an inkjet printer which has a simple structure and can perform double-sided printing and single-sided printing at high speed by rationalizing a paper conveyance procedure, and an inkjet printer using the same. The conventional printing method is provided.

[0004]

According to the present invention, a carriage which reciprocates, first and second heads mounted back to back on the carriage and ejecting ink in mutually opposite directions,
First and second printing units for carrying out printing by carrying a sheet in the sub-scanning direction with the paper facing the first and second heads when the carriage moves the first and second heads in the main scanning direction;
A paper carrying-in port and a paper discharging port, first and second paper carrying paths connecting the paper carrying-in port to the first and second printing units, respectively, and a first connecting the first and second printing unit to the paper discharging port, respectively. Third and fourth paper transport paths, U-shaped paper transport path, fifth and sixth paper transport paths connecting the first printing section to the entrance and the exit of the U-shaped paper transport path, and the second printing section It is an object of the present invention to provide an ink jet printer provided with seventh and eighth paper transport paths for connecting the U-shaped paper transport path to the exit and the U-shaped paper transport path, respectively.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A carriage according to the present invention has an ink head mounted thereon and reciprocates in the main scanning direction.
For example, it is slidably supported by a linear shaft and driven by a belt. The first and second heads are arranged back to back on the carriage and are configured to eject ink in mutually opposite directions. Each head, for example, ejects ink from the ink cartridge, ink nozzles, and ink from the ink cartridge. The ink nozzle is provided with a piezoelectric (piezo) element for controlling ejection. The ink cartridge is preferably replaceable, and may be common to both heads.

The first and second printing sections in the present invention are print execution points for supplying and discharging the paper at the printing speed in the sub-scanning direction with respect to the first and second heads, respectively.
The first and second printing units are provided with transport rollers capable of transporting the paper in the forward and reverse sub-scanning directions, and the first and second heads can print when the paper is transported in either sub-scanning direction. Is preferred.

Further, in preparation for the case where the first and second printing units pass the paper without printing, the conveying roller has a sub-operation speed (printing speed) suitable for printing, and a paper faster than that. It is preferable that it can be driven at a conveying speed.

The first to eighth sheet conveying paths and the U-shaped sheet conveying path in the present invention can be constituted by, for example, a known combination of a sheet guide member and a conveying roller. As the carrying rollers of the first to eighth paper carrying paths, those carrying the paper in only one direction can be used, which facilitates the rotation control of the carrying rollers.

Since the transport rollers provided in the paper transport path adjacent to the first and second printing units may carry the paper in or out at the printing speed with respect to the printing unit, the printing speed (low speed) may be exceeded. It is preferable to drive at both speeds of the sheet conveyance speed (high speed).

In the ink jet printer of the present invention, two sheets of paper may be sequentially conveyed from the paper carry-in port to the first and second printing units, and the first and second printing units may simultaneously print on each paper. . This improves the printing efficiency. Further, when performing single-sided printing on the first and second sheets, it is preferable to preferentially eject the first sheet. As a result, the paper discharge order is adjusted.

In the present invention, when single-sided printing is performed on different papers in the first and second printing units, the discharge speed of the paper that has finished printing in the first printing unit is controlled according to the printing state in the second printing unit. You may. This makes it possible to arrange the paper discharge order. When either one of the first and second applying units is incapable of printing (for example, the ink is out), it is possible to print on one or more sheets by only the other printing unit.

In the ink jet printer of the present invention, when double-sided printing is performed on a plurality of sheets, even if the odd-numbered and even-numbered sheets are conveyed on different conveying paths and are printed by the first and second printing units, respectively. Good. This improves the printing efficiency. In the present invention, at least one of the first to eighth paper transport paths may have a length corresponding to the length of the paper in the transport direction. As a result, paper collision is prevented.
When a sheet is carried in from the sheet carry-in port, it is preferable that after the trailing end of the carried-in sheet passes through the sheet carry-in port, the next sheet is carried in to the sheet carry-in port and printing is performed. Thereby,
Paper collisions are prevented.

In the ink jet printer of the present invention, when performing double-sided printing on the first and second sheets,
The sheet of paper is the paper carry-in port, the second paper transport path, the second printing section, the eighth paper transport path, the U-shaped paper transport path, the seventh paper transport path, the second printing section, the fourth paper transport path. Both sides are sequentially printed by the second printing section through the sheet discharging port and the sheet discharging port, and the second sheet is the sheet loading port, the first sheet transport path, the first printing section, the fifth sheet transport path, and the U-shaped sheet. It is preferable that double-sided printing is performed by the first printing unit via the transport path, the sixth paper transport path, the first printing unit, and the third paper transport path in this order. As a result, double-sided printing is efficiently performed.

When single-sided printing is performed on the first and second sheets, the first and second sheets are the paper inlet, the first sheet, and the first sheet.
The first sheet through the paper transport path, the first print unit, the fifth paper transport path, the U-shaped paper transport path, the seventh paper transport path, the second print unit, the fourth paper transport path, and the paper discharge port. It is preferable that the second sheet is printed by the second printing unit and the second sheet is printed by the first printing unit. As a result, single-sided printing is efficiently performed.

When single-sided printing is performed on the first sheet and double-sided printing is performed on the second sheet, the first sheet is single-sided printed by the second printing section, and the second sheet is the first printing section. Print on both sides with
The first sheet may be discharged before the second sheet.
As a result, single-sided printing and double-sided printing can be performed efficiently.

In the ink jet printer of the present invention, when double-sided printing is performed on the first sheet and single-sided printing is performed on the second sheet, the first sheet is double-sided printed by the second printing unit and the second sheet is printed. It is preferable that the first sheet is printed on one side by the first printing unit and the first sheet is discharged before the second sheet. As a result, printing is performed efficiently and the order of ejecting the sheets is adjusted.

The present invention further comprises a plurality of movable levers for restricting the conveyance path of the conveyed sheet, and the plurality of movable levers are urged in one direction by a drive lever driven by a drive source and a spring. It is preferably composed of a driven lever. By this, the traveling direction of the paper is correctly determined, and no collision occurs.

In the ink jet printer of the present invention, when single-sided printing is performed on a plurality of sheets, it is preferable that the first and second heads that move back and forth perform printing when moving forward or backward. As a result, it is possible to improve the printing efficiency by increasing the speed at the time of moving without printing.

When performing double-sided printing on a sheet, it is preferable that the front and back sides of the sheet have different print scanning directions of the first and second heads and a conveying direction of the sheet. Thereby, double-sided printing can be performed efficiently.

When printing four pages of information on two sheets of paper, the second printing unit prints the information of the second page on the first sheet of paper, and the first printing unit prints three pages of information on the second sheet of paper. The information of the page is printed, each paper is reversed, the information of the first page is printed on the first sheet by the second printing unit, and the information of the fourth page is printed on the second sheet by the first printing unit. Is printed,
The first sheet may be ejected and then the second sheet may be ejected. As a result, double-sided printing can be performed efficiently and the order of ejecting the sheets can be arranged.

Embodiments The present invention will be described in detail below based on the embodiments shown in the drawings. This does not limit the invention.
FIG. 1 is a side view of an ink jet printer according to an embodiment of the present invention. In the figure, the upper housing 1 is provided with a printing mechanism 3, and the lower housing 2 is provided with a paper tray 6 for storing unprinted paper and a paper discharge tray 4 for storing printed paper. A paper feed roller 5 is provided at an end of the paper tray 6, and the paper is fed from the paper tray 6 one by one to the paper carry-in port 3 a of the printing mechanism 3 by the paper feed roller 5, and the paper printed by the printing mechanism 3 is printed. Are discharged from the paper discharge port 3b to the paper discharge tray 4 and are stacked in order.

FIG. 2 is an explanatory view of the structure of the printing mechanism 3. As shown in the figure, the printing mechanism 3 is provided with a carriage 100 at the center, and two printing units 101 and 102 for carrying out printing work by ink misalignments 11 and 12 of two printing heads (described later) mounted on the carriage 100. Equipped with.

Further, the printing mechanism 3 includes a paper feed path 111 connecting the paper carry-in entrance 3a to the printing section 101, a paper carry path 112 connecting the paper carry-in entrance 3a to the printing section 102, and the print section 101 to the paper discharge opening 3b. Paper transport path 11 connected to
3, a paper transport path 114 connecting the printing unit 102 to the paper discharge port 3b, a U-shaped paper transport path 120, and the printing unit 101
Paper conveying paths 115 and 116, which are respectively connected to the inlet 120a and the outlet 120b of the letter paper conveying path 120, the printing unit 1
02 is an outlet 120b and an inlet 1 of the U-shaped paper conveyance path 120
The sheet conveying paths 117 and 118 are respectively connected to the sheet transporting unit 20a.

The sheet conveying paths 112 and 113 and the sheet conveying paths 116 and 118 respectively intersect at an intersection 121.
And 122 cross each other.

Conveying rollers R1, R4, R for conveying the paper
5, R6, R7, R8, and R9 are the paper carrying-in side of the paper carrying path 111, the entrance 120a of the U-shaped paper carrying path 120, the intermediate part 120c, the exit 120b, the intersecting part 122, and the intersecting part 1.
21 and 21 are provided on the paper discharge side of the paper transport path 114, respectively.

Further, the printing section 101 is provided with printing transport rollers R2 and R3, and the printing section 102 is provided with printing transport rollers R10 and R11.

Further, sheet detection sensors S6 and S5 are provided at the sheet carry-in port 3a and the sheet discharge port 3b, respectively. Further, the paper detection sensors S1 and S2 are connected to the printing unit 101.
In addition, sheet detection sensors S3 and S4 are provided in the printing unit 102, respectively.

Further, a drive lever L1 for selecting either the paper conveyance path 111 or 112 to guide the paper carried in from the paper carry-in entrance 3a, a driven lever L2 for preventing the reverse conveyance of the paper in the paper conveyance path 111. A driven lever L3 for preventing the reverse conveyance of the sheet from the printing unit 101 to the sheet conveyance path 116, and a driving lever L4 for selecting either the sheet conveyance path 116 or 117 to guide the sheet from the sheet conveyance path.
At the intersection 122, the paper is fed from the paper transport paths 116 to 11
8 is driven by the driven lever L5 that prevents the sheet from being conveyed to the sheet conveying path 116 from the sheet conveying path 116,
Or, a driving lever L6 for preventing the sheet from being mistakenly conveyed from 118 to 116, a driving lever L7 for preventing the sheet from being mistakenly conveyed from the sheet conveying path 112 to 113 or from 113 to 112 at the intersection 121, and a sheet. A driven lever L for preventing the reverse conveyance of the sheet on the conveyance path 112.
8. A driven lever L9 is provided to prevent the reverse conveyance of the sheet on the sheet conveyance path 117.

The drive levers L1, L4, L6, L7
Are driven by actuators as described below. The driven levers L2, L3, L5, L8, and L9 are biased by springs (not shown) and have a structure that allows the conveyance of the sheet in the forward direction but prohibits the conveyance in the reverse direction.

As shown in FIG. 3, the carriage 100 ejects the ink supplied from the replaceable ink cartridges 121 and 122 from the ink nozzles 11 and 12 onto the sheets P1 and P2 in accordance with independent print signals. The print heads 131 and 132 are mounted. Carriage 100
Is supported by a shaft 140 so as to be slidable in a direction perpendicular to the plane of the drawing, and is driven by a drive belt 141. The carriage 100 is provided in the photo interrupter 142, and the relative position with respect to the band-shaped slit plate 143 is monitored.

FIG. 4 is a block diagram showing the control circuit of the ink jet printer of this embodiment. As shown in the figure, the signal processing section C includes an input section K and sheet detection sensors S1 to S1.
S7, print data input section D, photo interrupter 142
The output signals from the printers are processed, the received signals are processed, and the print motors M1, M2, the transport motors M3 to M7, and the print head 1 are processed.
31, 132, the actuators A1 to A4, the paper feed motor M8, and the belt drive motor M9 are drive-controlled.

The printing motor M1 drives the printing conveyance rollers R2 and R3, and the printing motor M2 drives the printing conveyance rollers R10 and R11 so that they can be shifted and rotated forward and backward, respectively. The carrying motor M3 is the carrying roller R1, the carrying motor M4 is the carrying rollers R4 to R6, the carrying motor M5 is the carrying roller R7, and the carrying motor M6 is the carrying roller R8.
The transport motor M7 drives the transport roller R9 in a unidirectional rotation so as to be variable.

The actuators A1 to A4 drive the drive levers L1, L4, L6 and L7 respectively, the belt drive motor M9 drives the belt 141 (FIG. 3) so that the belt 141 (FIG. 3) can be shifted and forward and reverse, and the paper feed motor M8. Drives the paper feed roller (FIG. 1).

In the printing unit 101, the paper is the roller R
When being conveyed at the printing speed from 2 to R3 or from rollers R3 to R2, the ink nozzles 11 move from the left to the right of the paper when viewed from the ink nozzles 11 with respect to the traveling direction of the paper. Only at that time, ink is ejected to perform printing. That is, assuming that the ink nozzles 11 perform printing during the forward scan when the paper is conveyed in the direction from the rollers R2 to R3, the ink nozzles move in the forward path when the paper is conveyed in the direction from the rollers R3 to R2. Prints when scanning. In either case, the sub-scanning is performed in the direction from the front end to the rear end with respect to the traveling direction of the paper. The same applies to the printing unit 102.

The printing operation in such a configuration will be described below. Single-sided printing When performing single- sided printing on two sheets of paper P1 and P2 at the same time, first, as shown in FIG. 12
The sheet P2 is conveyed to the printing unit 102 at a conveying speed via 0, and then the second sheet P2 is conveyed from the sheet carry-in port 3a to the printing unit 101.
Transport at the transport speed up to.

The printing unit 102 feeds the paper P1 from the rollers R11 to R10 at the printing speed, and at the same time, the printing unit 101 feeds the paper P2 from the rollers R3 to R3 at the printing speed. At this time, the carriage 100 repeats the reciprocating movement, and the ink heads 11 and 12 eject the ink at the same time only in the forward path or the backward path to perform printing.

That is, the first sheet P1 is the sheet carry-in port 3
The sheet is inserted from a and is inserted at the sheet conveying speed by the conveying roller R1. The sheet P1 is conveyed along the dotted line in the figure at the sheet conveying speed, and when the sheet detection sensor S3 detects the leading edge of the sheet, the conveying speed is reduced to the printing speed by the conveying roller R11.

The trailing edge of the sheet P1 is the sheet detection sensor S.
When it is detected by 6, the second sheet P2 is continuously inserted from the sheet inlet, and when the sheet detection sensor S1 detects the leading edge of the sheet, the conveyance roller R2 similarly conveys the sheet P2 at the printing speed. Will be decelerated to. Then, the print heads 12 and 11 start printing on the sheets P1 and P2. In this case, the printing may be started at the same time, or the printing may be started first. Note that the driven lever L9 for changing the sheet conveying path is applied with a weight that is pushed up by the sheet conveying force. Therefore, there is no particular hindrance to the sheet conveyance.

When the printing of the paper P1 is completed, the transport rollers R10 and R9 are accelerated to the paper transport speed, and the paper P1 is discharged. If the paper P1 is being printed at the time when the printing of the paper P2 is finished, the conveyance speed of the paper P1 is set to the stopped state or the decelerated state without accelerating until the printing of the paper P1 is finished.

Therefore, when the printing on the sheet P1 is completed, the sheet P1 is preferentially discharged to the sheet discharge port 3b via the sheet conveying path 114 regardless of the printing state on the sheet P2. Next, when the printing of the paper P2 is completed, the paper P2
Is discharged via the paper transport paths 115, 120, 117, 114.

Ink cartridges 121 and 122
When one of the inks in FIG. 3 is used up, printing is performed using only the print head with the ink remaining in the ink cartridge. FIG. 6 shows a case where single-sided printing is performed using only the print head 132 (ink nozzles 12), and the papers P1 and P2 are sequentially loaded into the paper carry-in port 3a and the printing unit 1.
01, passing through the U-shaped paper conveyance path 120, the printing unit 102
Is printed, and the sheet is discharged from the sheet discharge port 3b.

When performing one-sided printing using only the print head 131 (ink nozzle 11), the papers P1 and P2 are sequentially carried into the printing section 101 from the paper carry-in port 3a, printed by the printing section 101, and printed in a U-shape. The sheet-shaped sheet conveying path 120 passes through the printing unit 102 and is discharged from the sheet discharge port 3b.

Double-sided Printing FIGS. 7 and 8 show a sheet conveying procedure when double-sided printing is performed on a plurality of sheets. As shown by the broken line in FIG. 7, the first sheet of paper is first printed on the front side by the printing unit 102 from the paper carry-in port 3a via the paper transport path 112, and the paper transport path 11
The U-shaped paper transport path 120 and the paper transport path 117 are reversed, and then the back surface is printed on the printing unit 102.
Is printed on the sheet and is discharged from the sheet discharge port 3b.

Next, as shown by the broken line in FIG. 8, the surface of the second sheet is printed by the printing section 101 from the sheet carry-in port 3a via the sheet conveying path 111.
It is inverted by passing through the U-shaped paper transport path 120 and the paper transport path 116, and then the back surface is printed by the printing unit 101 and discharged from the paper discharge port 3b via the paper transport path 113. In this case, both sides of the first sheet and the second sheet are printed by the dedicated printing unit.
Moreover, since the paper conveyance path is different, the printing efficiency is improved.

The length of the sheet conveying path 117 corresponds to the length in the sheet conveying direction so that the first sheet P1 and the second sheet P2 do not collide with each other as shown in FIG. Has been decided. Further, the length of the paper transport path 112 is also as shown in FIG.
When the leading edge of the first sheet of paper P1 is printed by the printing unit 102 as shown in FIG. 2, the length in the sheet transport direction is adjusted so that the trailing edge does not collide with the leading edge of the second sheet of paper P2 to be loaded next. It is decided according to

Further, as shown in FIG. 11, when the size of the first sheet P1 in the conveying direction is large and the trailing edge remains at the sheet carry-in port 3a, the second sheet P2 is carried in the sheet carry-in port. Waiting before 3a, the second sheet P2 is carried into the sheet carry-in port 3a after the trailing edge of the first sheet P1 enters the sheet transport path 112, thereby avoiding collision of the sheets P1 and P2. I am trying.

The printing operation outlined with reference to FIGS. 7 and 8 will now be described in more detail. As shown in FIG. 12, when the first sheet P1 is carried in at the sheet conveying speed and detected by the sheet detection sensor S6, the driving lever L1 operates to switch the conveyance of the sheet P1 toward the printing unit 102.
Immediately after the leading edge of the sheet passes through the lever L1, the operation of the lever L1 is stopped and the lever returns to its original position, but the pressure contact with the sheet does not hinder the progress of the sheet. When the paper detection sensor S4 detects the leading edge of the paper P1, the conveyance roller R8 slows down to the printing speed. Then, the printing unit 102 starts printing.

As shown in FIG. 13, when the trailing edge of the sheet P1 passes the conveying roller R1, the second sheet P2 is conveyed by the conveying roller R1. As for the sheet P2, when the leading edge of the sheet is detected by the sheet detection sensor S1, the transport roller R2 is driven at the sheet printing speed similarly to the sheet P1, and the printing unit 101 is operated.
Then, the paper is fed from the leading edge and printing is started. The drive lever L1 does not operate when the paper P2 is used.

Next, as shown in FIG. 14, when the printing of the paper P1 is completed, the carrying roller R11 is accelerated to the paper carrying speed, and the paper P1 continues to be the paper carrying rollers R7, R.
4, R5, R6 are conveyed, inverted, and returned to the conveyance roller 11 again. At this time, the transport rollers R11 and R10
Reverses the rotation direction and decelerates to the printing speed.
2 prints the back surface of the paper P1.

On the other hand, the sheet P2 passes the conveying rollers R3, R4, R5, R6 when the printing in the printing unit 101 is completed, and the lever L4 has the leading edge of the second sheet of the conveying roller R6.
Is activated before passing through the conveyance roller R.
Switch to direction 7. When the direction of the leading edge of the sheet P2 is switched to the direction of the transport roller R7, the lever L4 stops its operation and returns to its original position by the force of the spring as with the lever L1.
However, the pressure of the spring is not strong enough to hinder the conveyance of the paper.

Next, when the leading edge of the paper P2 is detected by the paper detection sensor S2, the carrying roller R7 reduces the carrying speed to the printing speed, and the rollers R3 and R2 also slow the carrying speed to the printing speed and rotate the driving direction. Reverse. Printing is started when the leading edge of the paper P2 reaches the position of the printing unit 101.

As shown in FIG. 15, after the printing of the sheet P1 is completed, the conveying rollers R10 and R9 are set at the sheet conveying speed and the sheet P is conveyed.
Discharge 1. After that, the paper P2 is conveyed by the transport rollers R8, R.
Discharged by 9. In this way, the sheets P1 and P2 are
Are efficiently transported so that they do not collide with each other or overlap each other, efficient double-sided printing is performed, and they are ejected in order.

Next, the relationship between the number of print sheets corresponding to the print data capacity (number of pages) and the sheet transport path will be described. The transport path is shown using transport rollers R1 to R11.

When the number of print sheets is 1 or 1 page, the sheets are conveyed in the following order and single-sided printing is performed. R1 → R2 → Printing part 101 (printing: none) → R3 → R4
→ R5 → R6 → R11 → Printing unit 102 (first page of printing) → R10 → R9 ・ In the case of page 2, the paper is conveyed in the following order and double-sided printing is performed. R1 → R2 → Printer 101 (Printing: First page) → R3
→ R4 → R5 → R6 → R7 → R3 → Printing part 101 (printing: second page) → R2 → R8 → R9

When the number of print sheets is two: When the number of pages is three (first side is double-sided printing, second side is single-sided printing), first and second pages are double-sided printed. R1 → R8 → R10 → Printing part 102 (printing: second page) → R11 → R7 → R4 → R5 → R6 → R11 → printing part 102 (printing: first page) → R10 → R9 Print the eyes on one side. R1 → R2 → Printing unit 101 (printing: 3rd page) → R3
→ R4 → R5 → R6 → R7 → R3 → Printing part 101 (printing: none) → R2 → R8 → R9 ・ For page 4 ・ Print on both sides of the first and second pages. R1 → R8 → R10 → Printing part 102 (printing: second page) → R11 → R7 → R4 → R5 → R6 → R11 → printing part 102 (printing: first page) → R10 → R9 ・ Second sheet 3, 4 Print on both sides of the page. R1 → R2 → Printing unit 101 (printing: 3rd page) → R3
→ R4 → R5 → R6 → R7 → R3 → Printing section 101 (printing: 4th page) → R2 → R8 → R9 ・ In case of 5 pages: Return to the case of 1 page, and so on.

In this embodiment, when a plurality of sheets of text are continuously printed at the same time, if the text is printed on one side, the print head prints only when moving on one side (outward). I have to. As a result, the method of driving the print head is simplified, the return speed of the print head in the non-printing time is increased, and the number of printed sheets is increased. That is, as shown in FIG. 16, when performing single-sided printing on the sheets P1 and P2, the print heads 131 and 1
With respect to the reciprocating movement of 32 (the reciprocating movement of the carriage 100), the printing timing is set only in the forward path, and the returning path of the print head returns at a high speed. In the return path of the print head, the print sheets P1 and P2 are conveyed to the next print area by one step.

In the case of double-sided printing, as shown in FIGS. 17 and 18 and Table 1, the print heads 131 and 132 perform printing when moving to both sides (reciprocating path). That is, the first sheet P1
The front surface of the second sheet P2 is printed in the forward path, the front surface of the second sheet P2 is the forward path, the back surface of the first sheet P1 is the forward path, and the front surface of the second sheet P2 is the backward path. This simplifies data processing when printing information to be printed on two sheets of paper P1 and P2.

In this case, the print heads 131, 13
When 2 is reciprocally driven, when the first sheet P1 is printed (return path), the second sheet is not printed, the sheet is moved to the next print pitch, and the print head returns. The print head 13 on P2 on the second sheet
No. 1 is printed and the first sheet of paper is not printed during that period (outward), and the first sheet of paper P1 is alternately printed so as to move to the next printing pitch, and the sheets are alternately moved. I do. This further simplifies data processing when the information to be printed on a sheet is printed on two sheets.

[0059]

[Table 1]

The double-sided printing process procedure on a plurality of sheets described above is summarized and organized as shown in the flowchart of FIG.

In FIG. 19, when the print data to be printed is four pages or more (step S1). Two sheets of paper are carried in (step S2), the ink nozzle 12 (print head 132) prints the second page on the first sheet, and the ink nozzle 11 (print head 131) prints the second page on the second sheet.
The page is printed at the same time (steps S3 and S4).
Next, the first and second sheets are reversed (step S
5) At the same time, the ink nozzle 12 prints the first page on the back surface of the first sheet and the ink nozzle 11 prints the fourth page on the back surface of the second sheet (steps S6 and S7). The second sheet is sequentially ejected (step S9).

The print data is reduced by 4 pages (step S10), and steps S2 to S10 are repeated. Then, if the remaining print data is for one page in step S1 (step S11), one sheet of paper is carried in, printing of one page is performed by the ink nozzles 12 and discharged (steps S12-). S14), the printing operation ends.

In step S1, the remaining print data is 2
If it is for pages (step S15), one sheet of paper is carried in, both sides are printed by the ink nozzles 11 and discharged (steps S16 to S20). Also, step S
If the remaining print data for 1 is 3 pages (step S21), 2 sheets of paper are carried in, and the 3rd page is simultaneously printed on the first sheet by the ink nozzles 12 (steps S22 to S24). ). Next, the two sheets are reversed, the first page is printed on the back surface of the first sheet by the ink nozzle 12, and the first and second sheets are sequentially ejected (steps S25 to S28). . In this way, double-sided printing can be performed efficiently, and the paper discharge order can be arranged in page order.

[0064]

According to the present invention, two carriages are provided in one carriage.
Since one print head is mounted and two heads can perform one-sided or double-sided printing on each sheet in order, it is possible to improve the printing efficiency and arrange the sheet discharge order.

[Brief description of drawings]

FIG. 1 is a side view of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main configuration of FIG.

FIG. 3 is an explanatory diagram of a main configuration of FIG.

FIG. 4 is a block diagram showing a control circuit of the embodiment.

FIG. 5 is an explanatory diagram showing a one-sided printing method according to the embodiment.

FIG. 6 is an explanatory diagram showing a printing method in the case of printing one sheet according to the embodiment.

FIG. 7 is an explanatory diagram showing a sheet conveyance path when performing double-sided printing on a plurality of sheets in the embodiment.

FIG. 8 is an explanatory diagram showing a sheet conveyance path when performing double-sided printing on a plurality of sheets in the embodiment.

FIG. 9 is an explanatory diagram showing the length of the paper transport path in the embodiment.

FIG. 10 is an explanatory diagram showing the length of the paper transport path in the embodiment.

FIG. 11 is an explanatory diagram illustrating a sheet conveyance process according to the embodiment.

FIG. 12 is a detailed explanatory diagram showing a double-sided printing procedure of the embodiment.

FIG. 13 is a detailed explanatory diagram showing a double-sided printing procedure of the embodiment.

FIG. 14 is a detailed explanatory diagram showing a double-sided printing procedure of the embodiment.

FIG. 15 is a detailed explanatory diagram showing a double-sided printing procedure of the embodiment.

FIG. 16 is an explanatory diagram showing a printing direction of a print head in single-sided printing according to an example.

FIG. 17 is an explanatory diagram showing a printing direction of a print head in double-sided printing according to an example.

FIG. 18 is an explanatory diagram showing a printing direction of a print head in double-sided printing according to an example.

FIG. 19 is a flowchart illustrating a procedure for printing on both sides of a plurality of sheets according to the embodiment.

[Explanation of symbols]

1 Upper housing 2 Lower housing 3 printing mechanism 3a Paper carry-in entrance 3b Paper outlet 4 Output tray 5 paper feed rollers 6 paper trays 101 printing section 102 printing section 111 Paper transport path 112 Paper transport path 113 paper transport path 114 paper transport path 115 paper transport path 116 paper transport path 117 Paper transport path 118 paper transport path 120 U-shaped paper transport path 120a entrance 120b exit R1 transport roller R2 transport roller R3 transport roller R4 transport roller R5 transport roller R6 transport roller R7 transport roller R8 transport roller R9 transport roller R10 transport roller R11 transport roller S1 paper detection sensor S2 Paper detection sensor S3 Paper detection sensor S4 Paper detection sensor S5 Paper detection sensor S6 Paper detection sensor L1 drive lever L4 drive lever L6 drive lever L7 drive lever L2 driven lever L3 driven lever L5 driven lever L8 driven lever L9 driven lever

Continuation of the front page (56) Reference JP-A-10-34902 (JP, A) JP-A-2-34396 (JP, A) JP-A-11-34403 (JP, A) JP-A-3-256762 (JP , A) JP 10-76713 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 3/54 B41J 2/01 B41J 3/60 B65H 29/60 B65H 85/00

Claims (17)

(57) [Claims] 1. A reciprocating carriage, first and second heads mounted back to back on the carriage and ejecting ink in mutually opposite directions, and when the carriage moves the first and second heads in the main scanning direction. First and second printing units that convey the paper in the sub-scanning direction by facing the first and second heads for printing, a paper carry-in port and a paper discharge port, and a paper carry-in port for the first and second printing First and second paper transport paths that are respectively connected to the respective units, third and fourth paper transport paths that respectively connect the first and second printing units to the paper exit, a U-shaped paper transport path, and a first paper transport path. Fifth and sixth paper transport paths that connect the printing unit to the inlet and outlet of the U-shaped paper transport path, respectively, and seventh and sixth paper paths that connect the second printing unit to the outlet and the inlet of the U-shaped paper transport path, respectively. Ink jet equipped with 8 paper transport paths Tprinter. 2. The ink jet printer according to claim 1, wherein at least one of the first to eighth sheet conveying paths has a length corresponding to a sheet length in a sheet conveying direction. 3. The first and second printing units are provided with transport rollers capable of transporting the paper in the forward and reverse sub-scanning directions, and the first and second heads transport the paper in either sub-scanning direction by the transport rollers. The ink jet printer according to claim 1, which is capable of printing even when the printing is performed. 4. A plurality of movable levers for restricting a conveyance path of a sheet to be conveyed, wherein the plurality of movable levers are a driving lever driven by a driving source and a driven lever biased in one direction by a spring. The inkjet printer according to claim 1, comprising: 5. The ink jet printer according to claim 1, wherein two sheets of paper are sequentially conveyed from the paper carry-in port to the first and second printing units, and the first and second printing units simultaneously print on each paper. A printing method characterized by being performed. 6. The printing method according to claim 2, wherein when single-sided printing is performed on the first and second sheets, the first sheet is preferentially discharged. 7. The printing method according to claim 2, wherein the discharging speed of the paper which has been printed by the first printing section is controlled according to the printing state of the second printing section. 8. The ink jet printer according to claim 1, wherein when either one is unable printing of the first and second indicia-shaped portion, characterized in that the printing on one or more sheets only the other of the printing unit And the printing method. 9. The ink jet printer according to claim 1, wherein when double-sided printing is performed on a plurality of sheets, the odd-numbered sheet and the even-numbered sheet are conveyed in different conveying paths, respectively. 2. A printing method characterized by printing at a printing section. 10. The inkjet printer according to claim 1, wherein when a sheet is carried in from a sheet carry-in port, the next sheet is carried in to the sheet carry-in port after the trailing end of the carried-in sheet has passed through the sheet carry-in port. , A printing method characterized by performing printing. 11. The inkjet printer according to claim 1, wherein when performing double-sided printing on the first and second sheets, the first sheet is a sheet inlet, a second sheet conveying path,
2nd printing part, 8th paper conveyance path, U-shaped paper conveyance path, 7th
Double-sided printing is performed by the second printing unit via the paper transport path, the second printing unit, the fourth paper transport path, and the paper discharge port in this order, and the second sheet of paper is loaded into the paper carry-in port, the first paper transport path, and the first paper transport path. 1 printing section,
5th paper transport path, U-shaped paper transport path, 6th paper transport path,
A double-sided printing method in which double-sided printing is performed in the first printing unit by sequentially passing through the first printing unit and the third sheet conveyance path. 12. The ink jet printer according to claim 1, wherein when performing first-side printing on the first and second sheets, the first and second sheets are the sheet inlet, the first sheet, and the first sheet.
The first sheet through the paper transport path, the first print unit, the fifth paper transport path, the U-shaped paper transport path, the seventh paper transport path, the second print unit, the fourth paper transport path, and the paper discharge port. The printing method is characterized in that the second sheet is printed by the second printing section and the second sheet is printed by the first printing section. 13. The ink jet printer according to claim 1, wherein when the first sheet is printed on one side and the second sheet is printed on both sides, the first sheet is printed on one side by the second printing unit. Double-sided printing on the second sheet in the first printing section,
A printing method characterized in that the first sheet is discharged before the second sheet. 14. The inkjet printer according to claim 1, wherein when double-sided printing is performed on the first sheet and single-sided printing is performed on the second sheet, the first sheet is double-sided printed by the second printing unit. Print one side of the second sheet with the first printing section,
A printing method characterized in that the first sheet is discharged before the second sheet. 15. The ink jet printer according to claim 1, wherein when performing single-sided printing on a plurality of sheets of paper, the first and second heads that reciprocate move perform printing when moving forward or backward. Printing method characterized by. 16. The ink jet printer according to claim 1, wherein when double-sided printing is performed on the paper, the print scanning direction of the first and second heads and the paper transport direction are different between the front surface and the back surface of the paper. Printing method. 17. The ink jet printer according to claim 1, wherein when printing four pages of information on two sheets of paper, the second printing unit prints information of the second page on the first sheet of paper. The first printing unit prints the information of the third page on the second sheet of paper, reverses each sheet, the second printing unit prints the information of the first page on the first sheet of paper, and the first printing unit Print the information on page 4 on the second sheet,
A printing method characterized in that a first sheet is ejected and then a second sheet is ejected.