JP2000211762A - Paper transport device for inkjet recording device - Google Patents

Abstract

(57) [Summary] (With correction) [Problem] When the rear end of the recording paper passes through the paper feed roller and is conveyed only by the discharge roller, the recording paper conveyance speed changes instantaneously and the recording paper moves. This increases the amount, and prevents the occurrence of a printing defect called "white spots" in the printed portion at the rear end. A paper feed roller provided upstream of an ink head, a paper suction conveyance belt provided facing the ink head, and a paper discharge roller provided downstream of the ink head. 11, the sheet conveying force F1 of the sheet feeding roller 8, the sheet conveying force F2 of the sheet suction conveying belt 10, and the sheet conveying force F3 of the sheet discharging roller 11 are expressed as F1> F.
3> F2, and the paper transport speed V1 of the paper feed roller 8
And the paper transport speed V2 of the paper suction transport belt 10 and the paper transport speed V3 of the paper discharge roller 11 are calculated as follows: V3>V2> V1
Is set to

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed roller provided upstream of a recording head for discharging ink from a nozzle to print an image on recording paper, and a paper suction provided opposite the recording head. An ink jet recording apparatus comprising a transport belt and a paper discharge roller provided downstream of the recording head, and transporting the recording paper with a predetermined gap from the recording head by a paper feed roller, a paper suction transport belt, and a paper discharge roller Related to a paper transport device.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording apparatus for printing an image on a recording sheet by discharging ink from nozzles of a recording head has been put into practical use, and a recording head faces a recording surface of a recording sheet being conveyed. The recording paper is sucked and conveyed by a paper suction conveyance belt to a position facing the recording head, and ink is ejected from nozzles of the recording head to perform printing on the recording paper. In this case, the recording paper is conveyed by one scan for printing, and printing is performed. Conventionally, in such an ink jet recording apparatus, by setting the gap between the recording paper and the ink ejection surface of the nozzle of the recording head to about 1 mm or less, it is possible to secure stable printing performance and obtain high printing quality. It was possible. Therefore, the following method has been used to realize stable conveyance of the recording paper.

(1) In general, an appropriate tension is applied to a recording sheet at a printing position facing a recording head having a nozzle (Japanese Patent Application Laid-Open No. Hei 8-90858). As shown in FIG.
Is set to be slightly higher than the peripheral speed Sf of the paper discharge roller 22 disposed on the downstream side of the recording head in the paper transport direction of the recording head. Se> Sf), and a recording paper P conveyed during this time is subjected to a tensile force so as not to bend.

(2) Paper feed rollers are provided upstream and downstream of the recording head, and the paper transport speed of the paper feed rollers provided downstream is adjusted by the paper feed rollers provided upstream. In some cases, the recording paper is set to be slightly higher than the transport speed, and the bending of the recording paper at the position facing the recording head is eliminated.

(3) A recording paper suction means is disposed at a position facing the recording head, and the recording paper conveyed by the paper feed roller is suctioned by the recording paper suction means, so that the recording paper comes into contact with the recording head. There was something that was not allowed.

[0006]

In general, in an ink jet recording apparatus of an ink jet system which performs printing by directly ejecting ink onto recording paper, the distance between the recording paper and the recording head can be set so that the two do not come into contact with each other. There are many advantages in printing if it is as close as possible. For this reason, in order to perform high-quality printing, it is indispensable to prevent waving and bending that occur with the conveyance of the recording paper.

However, in the ink jet recording apparatus using the above-mentioned method (1), as shown in FIG. 11, printing defects generally called "white spots" tend to occur in the printing portion at the rear end of the recording paper. There were drawbacks.

[0008] The cause of this is considered as follows. That is, when printing is performed on the trailing edge of the recording paper, the peripheral speed S of the paper feed roller 23 is changed as shown by a two-dot chain line in FIG.
In a sheet transport apparatus in which f is set to be smaller than the peripheral speed Se (> Sf) of the discharge roller 22, the trailing end Pe of the recording paper P is separated from the nip point of the paper feed roller 23 and the front discharge roller It will be fed by only 22
When the recording paper P leaves the nip point of the paper feed roller 23, the recording paper P
The back tension from the paper feed roller 22 whose peripheral speed is relatively reduced does not work.

Therefore, the paper feed speed instantaneously increases from the steady value Vo to a certain speed Vx (> Vo). As a result, for example, as shown in FIG. This causes a printing defect that is abnormally enlarged.

Further, when the above (2) and (3) are applied, the specific paper transport speed is determined only by the magnitude of the paper transport speed of the transport rollers constituting the paper transport path along the paper transport direction. (However, the paper transport speed of the downstream paper transport roller is increased with respect to the paper transport speed of the upstream paper transport roller) and the balance of the paper transport force between each transport roller are not mentioned. Whether or not the increase in the line feed amount Dx of only the last line generated in the method (1) can be eliminated is not sufficient only by setting the paper transport speed on the upstream side and the downstream side.

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper transport device of an ink jet recording apparatus which can solve the above-mentioned problems and can transport a recording paper stably with a good precision.

[0012]

According to a first aspect of the present invention, there is provided a paper feeder provided upstream of a recording head for ejecting ink from nozzles to print an image on recording paper. A roller, a paper suction conveyance belt provided facing the recording head, and a paper discharge roller provided downstream of the recording head, and the recording paper is fed by a paper supply roller, a paper suction conveyance belt, and a paper discharge roller. In a sheet conveying device of an ink jet recording device that conveys a recording head with a predetermined gap, a sheet conveying force F1 of the sheet feeding roller;
The sheet conveyance force F2 of the sheet suction conveyance belt and the sheet conveyance force F3 of the sheet ejection roller are set to F1>F3> F2, and the sheet conveyance speed V1 of the sheet supply roller and the sheet conveyance speed V2 of the sheet adsorption conveyance belt are set. And the paper transport speed V3 of the paper discharge roller
Are set to V3>V2> V1.

According to a second aspect of the present invention, the distance between the paper feed roller and the paper discharge roller is set to be shorter than the length of the recording paper in the conveying direction.

According to a third aspect of the present invention, the sheet suction and conveyance belt is stretched over a driving roller and a driven roller, and the stretch width of the sheet suction and conveyance belt from the driving roller to the driven roller is set to the width of the recording head. It is set larger than the print width.

According to a fourth aspect of the present invention, the recording paper supply means for guiding the recording paper to the paper supply roller is disposed upstream of the paper supply roller, and the paper transportation force and the paper transportation speed of the recording paper supply means are provided. Is set smaller than the sheet conveying force of the sheet feeding roller and the sheet conveying speed.

According to a fifth aspect of the present invention, a recording paper supporting means for supporting and conveying printed recording paper discharged from the paper discharge roller is disposed downstream of the paper discharge roller. The sheet conveying force and the sheet conveying speed of the sheet supporting means are set smaller than the sheet conveying force and the sheet conveying speed of the sheet discharging roller.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ink-jet printer which is an ink-jet recording apparatus using a sheet conveying device of the present invention will be described with reference to FIGS.

In this ink jet printer, a paper feed tray 2 is provided at a lower portion of a side of a printer main body 1, and a paper discharge tray 3 is provided above the paper feed tray 2. The paper feed tray 2 is provided with a slide paper fixing plate 4 for guiding the side of the recording paper P.

In the printer body 1, a pickup roller 5 for picking up only the uppermost one of the plurality of recording sheets P placed on the sheet feed tray 2, and the recording picked up by the pickup roller 5 are provided. Paper feed roller 6 for transporting paper P, paper transport path 7 for transporting recording paper P transported by paper feed roller 6, and paper transport path 7
Roller 8 that feeds recording paper P conveyed through the printer to the printing unit at a timed timing;
An ink head 9, which is a recording head that performs printing by ejecting ink to a recording paper P fed by a printer, and a paper suction that is disposed to face the ink head 9 and adsorbs the recording paper P and conveys the recording paper P to a printing area by the ink head 9. A conveyance belt 10, a paper discharge roller 11 for discharging the recording paper P after printing conveyed by the paper suction conveyance belt 10, and drying the ink printed on the recording paper P discharged by the paper discharge roller 11 An ink drying unit 12 and a paper discharge roller 13 that discharges the recording paper P on which ink has been dried by the ink drying unit 12 to the paper discharge tray 3 are provided.

The ink head 9 includes an ink tank 14
And an ink nozzle (not shown) for discharging ink provided at the tip of the ink tank 14, and the ink head 9 is held by a holding shaft 15. Then, the registration roller 8 and the sheet suction conveyance belt 10
And the paper discharge roller 11 constitute a paper transport device.

The printing operation of the ink jet printer having the above configuration will be described. When a printing request based on image information from a control unit (not shown) is made, the pickup roller 5
, One sheet of recording paper P is fed from the paper feed tray 2,
The fed recording paper P is fed to the registration roller 8 through the paper feed roller 6 and the paper transport path 7.

The recording sheet P is fed to the sheet suction / conveyance belt 10 by the registration roller 8 with the conveyance timing adjusted so that the leading end of the image information and the leading end of the sheet coincide with each other based on the image information.

The paper suction conveyance belt 10 suctions the recording paper P and conveys it to the printing area by the ink head 9, and stops the conveyance once the recording paper P reaches the printing area.
When the recording paper P is stopped in the printing area, the ink head 9
The ink is ejected from the ink nozzles to the recording paper P based on the image information while printing is moved in the direction perpendicular to the paper transport direction, and printing is performed.

At the time when the printing of one line (one direction) of the ink head 9 is completed, the registration roller 8, the paper suction conveyance belt 10, and the paper ejection are moved by a moving amount corresponding to a plurality of ink nozzles of the ink head 9. The recording paper P is conveyed by a paper conveying device including rollers 11 and printing is performed based on image information in the same manner as described above. When all printing on one recording paper P is completed, the recording paper P is dried by the paper conveying device by the ink drying unit 12. Then, the ink printed on the surface of the recording paper P is dried by the ink drying unit 12, and the recording paper P is discharged to the discharge tray 3 by the paper discharge rollers 13.

Next, in the first embodiment of the paper transport apparatus including the registration roller 8, the paper suction transport belt 10, and the paper discharge roller 11, the paper transport force of each of the registration rollers 8, the paper suction transport belt 10, and the paper discharge roller 11 will be described. The paper transport speed is set as shown in Table 1.

[0026]

[Table 1]

If the sheet conveying force of each of the registration rollers 8, the sheet suction conveying belt 10, and the sheet discharging roller 11 is set to the sheet conveying force as shown in Table 1, the outer side of the recording sheet P is irrespective of the position of the recording sheet P. , And a stable paper transport is performed.

FIG. 3 shows the sheet conveying operation according to the first embodiment.
5 through FIG.

(1) As shown in FIG. 3, after the leading edge of the recording paper P has passed through the registration rollers 8,
Until the recording paper P is transported by the registration rollers 8 and the paper suction transport belt 10 until the recording paper P is reached.

At this time, the sheet conveyance force F1 of the registration roller 8 is larger than the sheet conveyance force F2 (sheet adsorption force) of the sheet suction conveyance belt 10, and the registration roller 8 is higher than the sheet conveyance speed V2 of the sheet adsorption conveyance belt 10. 8, the recording paper P is not conveyed to the paper suction / conveyance belt 10 and the recording paper P slips on the paper suction / conveyance belt 10 and the paper conveyance speed of the registration rollers 8 Because it is transported at the speed of V1,
A pulling force f1 acts toward the upstream side in the sheet transport direction.

(2) As shown in FIG. 4, the leading end of the recording sheet P passes through the discharge roller 11 and the trailing end of the recording sheet P is located upstream of the registration roller 8 in the sheet transport direction. During this time, the recording paper P is transported by the registration roller 8, the paper suction transport belt 10, and the paper discharge roller 11.

At this time, the sheet conveying force is smaller in the order of the sheet conveying force F1 of the registration roller 8, the sheet conveying force F3 of the sheet discharging roller 11, and the sheet conveying force F2 of the sheet suction conveying belt 10 (F1>F3> F2). The paper conveyance speed is set, the paper conveyance speed V3 of the paper discharge roller 11, the paper suction conveyance belt 10
Are set smaller (V3>V2> V1) in the order of the sheet conveyance speed V2 of the registration roller 8 and the sheet conveyance speed V2 of the registration roller 8. Registration roller 8
, The pulling forces f1 and f2 are directed toward both the upstream side and the downstream side in the sheet conveying direction.
Acts.

(3) As shown in FIG. 5, after the leading edge of the recording paper P has passed through the registration rollers 8, the recording paper P is transported by the paper suction transport belt 10 and the discharge roller 11. .

At this time, the sheet conveyance force F3 of the sheet discharge roller 11 is larger than the sheet conveyance force F2 of the sheet suction conveyance belt 10, and the sheet conveyance speed is equal to the sheet conveyance speed V3 of the sheet discharge roller 11. The recording sheet P is conveyed at a sheet conveying speed V3 of the sheet discharging roller 11 in a state where a resistance (brake) is applied by the sheet adsorbing and conveying belt 10 because the sheet conveying speed is higher than the sheet conveying speed V2 of the sheet adsorbing and conveying belt 10. The tensile force f toward the downstream side in the paper transport direction.
2 works.

As shown in Table 1 above, assuming that the sheet conveying speed V1 of the registration roller 8 is 1, the sheet conveying speed V2 of the sheet suction conveying belt 10 is 1.1 times the sheet conveying speed V1 of the registration roller 8. , And the paper transport speed V3 of the discharge roller 11 is set to be about 1.2 times the paper transport speed V1 of the registration roller 8.

That is, in the paper transport apparatus of the first embodiment, the paper transport speed of the rollers (belts) positioned adjacent to each other and located on the upstream side in the paper transport direction for transporting the paper is about 10
It is set to increase by%.

In the present invention, the roller diameters of the registration roller 8 and the paper discharge roller 11 are set to 12 mm, and the roller diameters of the drive roller 10a and the driven roller 10b of the sheet suction and conveyance belt 10 are set to 25 mm. Since the paper transport speed can be freely set depending on the setting of the number of rotations to be given, the relationship between the paper transport speed of the registration roller 8, the paper suction transport belt 10, and the paper discharge roller 11 as shown in Table 1 is maintained. As far as possible, the diameter of each roller may be freely set.

The registration roller 8 and the discharge roller 1
The distance from the registration roller 8 provided with 1 to the paper discharge roller 11 is set shorter than the length of the recording paper P in the paper transport direction.

As shown in FIG. 6, when the recording roller P is conveyed by the registration roller 8 and the discharge roller 11 arranged as described above, the leading edge of the recording paper P is registered at the timing T1. At the timing of T2, the leading end of the recording paper P reaches the printing start position, at the timing of T3, the trailing edge of the recording paper P reaches the registration roller 8, and at the timing of T4, the trailing edge of the recording paper P. The end reaches the printing end position, and the trailing end of the recording paper P reaches the discharge roller 11 at the timing of T5.

Accordingly, the range H1 at which the recording paper P is transported at the paper transport speed V1 of the registration rollers 8 is at the timing T
1 to the timing T3, the printing range H2 of the recording paper P is between the timing T2 and the timing T4, and the range H3 of the recording paper P that is transported at the paper transport speed V3 of the discharge rollers 11 is from the timing T3 to the timing T3.
It will be between 5.

As shown in FIG. 7, the transport timing of the recording paper P at the time of printing for printing a plurality of recording papers P continuously is as shown in FIG. 8, the leading edge of the recording sheet P reaches the printing start position at the timing of Ta2, the trailing edge of the recording sheet P reaches the registration roller 8 at the timing of Ta3, and the trailing edge of the recording sheet P at the timing of Ta4. Reaches the printing end position, and the rear end of the recording paper P reaches the discharge roller 11 at the timing of Ta5.

Accordingly, the range Ha1 of the recording paper P conveyed by the registration roller 8 at the paper conveyance speed V1 is between the timing Ta1 and the timing Ta3, and the printing range Ha2 of the recording paper P is from the timing Ta2 to the timing Ta3.
4, the range Ha3 in which the recording sheet P is conveyed at the sheet conveying speed V3 of the discharge roller 11 is between the timing Ta3 and the timing Ta5.

Then, at a time interval Th from timing Ta5 to Tb1, the leading end of the second recording sheet P reaches the registration roller 8 at timing Tb1, and the leading end of the recording sheet P reaches the printing start position at timing Tb2. And Tb3
The trailing edge of the recording sheet P reaches the registration roller 8 at the timing of Tb4, the trailing edge of the recording sheet P reaches the printing end position at the timing of Tb4, and the trailing edge of the recording sheet P at the timing Tb5. To reach.

Accordingly, the range Hb1 of the recording paper P conveyed by the registration roller 8 at the paper conveyance speed V1 is between the timing Tb1 and the timing Tb3, and the printing range Hb2 of the recording paper P is from the timing Tb2 to the timing Tb3.
4, and the range Hb3 in which the recording sheet P is conveyed at the sheet conveying speed V3 by the discharge roller 11 is between the timing Tb3 and the timing Tb5.

The dimensions and the positional relationship of each member having the above configuration will be described with reference to FIG. 8. The registration roller 8 includes a pair of rollers, a roller 8a having a diameter of 12 mm and a roller 8b having a diameter of 5 mm. The endless belt is a driving roller 10a having a roller diameter of 25 mm.
And the driven roller 10b. Discharge roller 11
Is composed of a pair of rollers, a roller 11a having a diameter of 12 mm and a roller 11b having a diameter of 8 mm. The paper discharge roller 13 on the downstream side of the ink drying unit 12 includes a roller 13a having a diameter of 12 mm and a roller 13b having a diameter of 10 mm.
And a pair of rollers.

The distance L1 from the registration roller 8 to the driving roller 10a of the sheet suction and conveyance belt 10 is set to 20 mm, and the belt stretching distance L2 from the driving roller 10a to the driven roller 10b of the sheet suction and conveyance belt 10 is 50 m.
m, the driven roller 1 of the paper suction conveyance belt 10
The distance L3 from 0b to the paper discharge roller 11 is set to 20 mm, and the distance L4 from the paper discharge roller 11 to the paper discharge roller 13 is set to 150 mm.

The print width h1 of the ink head 9 in the paper transport direction is set to 40.6 mm, and the gap h2 between the ink head 9 and the paper suction transport belt 10 is 1.3 mm.
Is set to

As described above, by setting the belt stretching distance L2 of the sheet suction and conveyance belt 10 to be larger than the printing width h1 of the ink head 9, at least the printing width of the ink head 9 of the recording paper P is obtained. The suction force of the sheet suction and conveyance belt 10 is applied to the entire area corresponding to the above, and this portion can be surely sucked to the sheet suction and conveyance belt 10, and the gap h 2 between the ink head 9 and the recording sheet P is set to a predetermined value. The gap can be reliably maintained, the bending (floating) in the printing width (printing area) of the recording paper P can be eliminated, and the printing quality can be maintained at high quality.

In the first embodiment, as shown in FIG. 2, a paper feed roller 6 is provided between the registration roller 8 and the paper feed tray 2 on the upstream side in the paper conveyance direction. The roller 6 is made of metal or rubber having a roller diameter of 10 mm, and the sheet conveying speed is set to about the same as that of the registration roller 8 and the sheet conveying force is set to 500 gf. At this time, the sheet conveying force of the registration roller 8 is set to 2 kgf.

Thus, the recording paper P is transported at the paper transport speed of the registration roller 8 having a large paper transport force, and the paper transport speed of the paper feed roller 6 and the registration roller 8 are equal. The pulling force applied to the paper P is in the same state as in the case of the balance of the paper transporting force described with reference to FIG. 5, and the pulling force acts on the recording paper P toward the downstream side in the paper transporting direction.

Accordingly, it is possible to prevent the recording paper P from being bent due to the excessive feeding of the paper feed roller 6, and to maintain a constant gap between the ink head 9 and the recording paper P to perform high quality printing. It can be carried out.

The paper discharge roller 1 is located between the ink drying unit 12 and the paper discharge tray 3 on the downstream side of the paper discharge roller 11.
The paper discharge roller 13 is a cylindrical stainless steel roller 13a having a roller diameter of 12 mm, and a star-shaped irregular cross section having a roller diameter of 10 mm while maintaining a predetermined distance from the cylindrical roller 13a. And a stainless steel roller 13b having the following.

The paper transport speed of the paper discharge roller 13 is about 1.3 times the paper transport speed of the registration roller 8 and the paper transport force is 300 gf.
Is about 1.2 times the paper transport speed of the registration rollers 8, and the paper transport force is 600 gf.

As a result, the recording paper P is transported at the paper transport speed of the paper discharge roller 11 having a large paper transport force, and
Since the paper conveyance speed of the paper discharge roller is faster than the paper conveyance speed of the paper discharge roller, the pulling force applied to the recording paper P is in the same state as in the case of the balance of the paper conveyance force described in FIG. A pulling force acts on the downstream side in the paper transport direction.

Accordingly, it is possible to prevent the recording paper P from being bent due to a delay in feeding of the paper discharge roller 13, and to maintain a constant gap between the ink head 9 and the recording paper P to perform high-quality printing. It can be carried out.

[0056]

According to the first aspect of the present invention, the sheet conveying force F1 of the sheet feeding roller, the sheet conveying force F2 of the sheet suction conveying belt, and the sheet conveying force F3 of the sheet discharging roller are expressed as F1> F3.
> F2, and the sheet conveying speed V1 of the sheet feeding roller, the sheet conveying speed V2 of the sheet suction conveying belt, and the sheet conveying speed V3 of the sheet discharging roller are set as V3>V2> V1, so that In the range where the recording paper is conveyed by the paper roller and the paper suction conveyance belt, the recording paper is conveyed at the conveyance speed of the paper feed roller while receiving the suction force of the paper suction conveyance belt, so that the recording paper warps. Also, in the range where the recording paper is transported by the paper feed roller, paper suction transport belt, and paper discharge roller, the recording paper is transported at the transport speed of the paper feed roller while receiving the suction force of the paper suction transport belt. Therefore, the recording paper is not bent, and the recording paper is conveyed by the paper suction conveyance belt and the discharge roller even when the recording paper is conveyed. Because reluctant recording sheet conveyed at the conveying speed of the discharge roller is performed, no deflection occurs in the recording sheet,
A stable transport state can be obtained.

Further, when the recording paper is conveyed only by the paper feed roller or the paper discharge roller, a paper conveyance force in a direction opposite to the paper conveyance force acting on the recording paper by each roller is applied by the paper suction conveyance belt. In this state, a force is applied to pull the recording paper outward, and the recording paper can be transported in a stable state without bending, and high-quality printing can be performed.

According to the second aspect of the present invention, since the distance between the paper feed roller and the paper discharge roller is set shorter than the length of the recording paper in the transport direction, the trailing end of the recording paper is formed by the paper feed roller. When the paper is transported by the paper discharge rollers after passing through, the paper transport speed of the paper suction transport belt is smaller than the paper transport speed of the paper discharge rollers. Since the sheet conveying force is applied to the recording sheet, the amount of movement of the recording sheet does not increase instantaneously, and the occurrence of white spots at the trailing edge of the recording sheet can be reliably prevented.

According to the third aspect of the present invention, the paper suction / conveyance belt is stretched between the driving roller and the driven roller.
Since the stretch width of the paper suction and conveyance belt from the drive roller to the driven roller is set to be larger than the print width of the print head, the print width of the print head, that is, the floating of the print paper in the print area is reliably prevented. High quality printing can be performed.

According to the fourth aspect of the present invention, the recording paper supply means for guiding the recording paper to the paper supply roller is provided upstream of the paper supply roller, and the paper conveyance force of the recording paper supply means is supplied. Since the paper conveyance force of the roller is set to be smaller than that of the paper conveyance roller, it is possible to reliably prevent the recording paper feeding means from bending the recording paper too much to the paper feed roller in the paper conveyance range by the paper feed roller. .

According to the fifth aspect of the present invention, the recording paper supporting means for supporting and conveying the printed recording paper discharged from the paper discharging roller is disposed downstream of the paper discharging roller.
Since the sheet conveying force and the sheet conveying speed of the recording sheet supporting means are set to be smaller than the sheet conveying force and the sheet conveying speed of the sheet discharging roller, the feeding delay by the recording sheet supporting means in the sheet conveying range by the sheet discharging roller. Can be reliably prevented from being generated.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an embodiment of an ink jet printer using a paper transport device of the present invention.

FIG. 2 is a structural explanatory diagram showing each unit that feeds, conveys, and prints recording paper in the inkjet printer of FIG. 1;

FIG. 3 is an explanatory diagram illustrating a pulling force applied to a recording sheet P when a sheet is conveyed by a registration roller according to the first embodiment of the sheet conveying apparatus of the present invention.

FIG. 4 is an explanatory diagram illustrating a pulling force applied to a recording sheet P when the sheet is conveyed by a registration roller, a sheet suction conveyance belt, and a discharge roller according to the first embodiment of the sheet conveyance device of the present invention.

FIG. 5 is an explanatory diagram illustrating a pulling force applied to a recording sheet P when the sheet is conveyed by a sheet discharging roller according to the first embodiment of the sheet conveying apparatus of the present invention.

FIG. 6 is a diagram illustrating a sheet suction device according to a first embodiment of the present invention.
5 is a timing chart for explaining sheet conveyance timing by each member when printing one recording sheet.

FIG. 7 is a diagram illustrating a sheet conveying device according to a first embodiment of the present invention.
6 is a timing chart for explaining sheet conveyance timing by each member when printing a plurality of recording sheets.

FIG. 8 is an explanatory diagram for explaining an arrangement positional relationship of each part of the sheet conveying device of the present invention.

FIG. 9 is an explanatory diagram illustrating a pulling force applied to a recording sheet when a sheet is conveyed by upstream and downstream sheet feed rollers in a conventional sheet conveying apparatus.

FIG. 10 is an explanatory diagram illustrating a pulling force applied to a recording sheet when a sheet is conveyed by a downstream sheet feed roller in a conventional sheet conveying apparatus.

FIG. 11 is an explanatory diagram showing a print pattern of recording paper printed by a conventional paper transport device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer main body 2 Paper feed tray 3 Paper discharge tray 6 Paper feed roller 8 Registration roller 9 Ink head 10 Paper suction conveyance belt 11 Paper discharge roller 13 Paper discharge roller

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Yoshi ▼ Murahisa 22-22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka F-term (reference) 2C056 HA28 HA29 HA30 2C059 BB06 BB07 BB12 BB15 BB16 BB21 3F049 DA19 EA13 EA14 FB01 LA07 LB03

Claims (5)

[Claims] 1. A paper feed roller provided upstream of a recording head that prints an image on recording paper by discharging ink from nozzles, a paper suction conveyance belt provided opposite the recording head, and a recording head A paper feed roller of an ink jet recording apparatus, comprising a paper discharge roller provided on the downstream side of the printer, and conveying the recording paper at a predetermined gap from the recording head by a paper feed roller, a paper suction / conveyance belt, and a paper discharge roller. The paper transport force F1 of the paper feed roller, the paper transport force F2 of the paper suction transport belt, and the paper transport force F3 of the paper discharge roller
Is set to F1>F3> F2, and the sheet conveying speed V1 of the sheet feeding roller, the sheet conveying speed V2 of the sheet suction conveying belt, and the sheet conveying speed V3 of the sheet discharging roller are set to V3>V2> V1. A sheet conveying device for an ink jet recording apparatus, comprising: 2. The paper transport device of an ink jet recording apparatus according to claim 1, wherein the distance between the paper feed roller and the paper discharge roller is set shorter than the length of the recording paper in the transport direction. 3. The paper suction and conveyance belt is stretched over a driving roller and a driven roller, and the stretch width of the paper suction and conveyance belt from the driving roller to the driven roller is set to be larger than the printing width of the recording head. 2. The sheet conveying device for an ink jet recording apparatus according to claim 1, wherein 4. A recording paper supply means for guiding recording paper to the paper supply roller is provided upstream of the paper supply roller, and the paper conveyance force and paper conveyance speed of the recording paper supply means are adjusted by the paper supply roller. 2. The sheet conveying device of an ink jet recording apparatus according to claim 1, wherein the conveying force and the sheet conveying speed are set smaller than each other. 5. A recording paper supporting means for supporting and transporting printed recording paper discharged from the paper discharging roller is provided downstream of the paper discharging roller, and the recording paper supporting means transports the paper. 2. The sheet conveying device of the ink jet recording apparatus according to claim 1, wherein the force and the sheet conveying speed are set smaller than the sheet conveying force and the sheet conveying speed of the sheet discharging roller.