JPH11349171A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and exactly convey a paper by forming at least one of a conveying roller and a driven roller on which a paper conveying belt is laid by a taper roller of which a center portion is flat and both ends are formed to a taper shape and forming a shorter width of the flat portion than that of the conveying belt. SOLUTION: Paper taken out from a paper supplying cassette 13 fed to a conveying belt 23 and an image is recorded on the paper 3 by jetting an ink responsive to a printed image from a recording head 14 while the paper is electrostatically adsorbed to the conveying belt 23 and is conveyed. At this time, a driven roller 22 on which the conveying belt 23 is lied is made to a taper roller and a width (a length) L in a main scanning direction of a flat portion of the driven roller 22 is set so as to be shorter than that of the conveying belt 23. Thereby, both ends of the conveying belt 23 are faced to a taper portion of the driven roller 22 and it is prevented that the conveying belt approached to one side of the main scanning direction and is waved to stably and exactly convey the paper 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus capable of adjusting a gap between a recording head and a sheet.

[0002]

2. Description of the Related Art An ink jet recording apparatus used as an image recording apparatus such as a printer, a facsimile, a copying apparatus, etc.
Ink droplets are ejected from the nozzles (ejection ports) of the inkjet head to form a sheet (meaning that an image is recorded,
Not limited to paper. ), The image quality is degraded if the relative positional relationship between the recording head and the sheet is deviated. Therefore, it is necessary to stably and accurately convey the sheet.

Conventionally, as a paper transporting device in a general recording apparatus, there is known a paper transporting device using a transport belt as described in, for example, JP-A-6-80268. . In such a belt transport device, a roll having a constant outer diameter is conventionally used as a roll (roller) for supporting the transport belt in a planar shape. However, in the paper transport device described in the publication,
A roll in which a drum-shaped core shaft is coated with an elastic layer having a constant outer diameter so that the roll is uniformly deformed in the axial direction even when the roll is deformed by the tension of the conveyor belt, or A roll in which a drum-shaped elastic body layer is coated on a core shaft having a constant outer diameter is used.

[0004]

However, in the ink jet recording apparatus, the relative positional relationship between the recording head and the paper is deviated because an ink droplet lands on the paper to record an image as described above. For example, if the gap from the head to the paper fluctuates, flying ink droplets become unstable, causing variations in landing positions and landing dot diameters, resulting in reduced image quality or paper contacting the nozzle surface of the head and marking. Image quality is degraded due to, for example, dirty imaged surfaces.
Further, even when the paper moves in the main scanning direction, the landing positions of the ink droplets vary, and the image quality deteriorates.

However, when the paper is transported by an elastic transport belt in particular, a roll having an elastic layer having a drum-shaped outer shape, like the above-described conventional paper transport apparatus using a transport belt, or When the transport belt is rotated using a roll having a constant outer diameter, the transport belt may undulate or shift in the main scanning direction. Immediately reflected, it is difficult to obtain stable image quality.

[0006] The present invention has been made in view of the above points, and has as its object to provide an ink jet recording apparatus capable of stably and accurately conveying a sheet.

[0007]

According to a first aspect of the present invention, there is provided an ink jet recording apparatus which conveys a sheet by a conveying belt, discharges ink droplets from a recording head, and prints an image on the sheet. In the inkjet recording apparatus for printing, at least one of the transport roller and the transport driven roller on which the transport belt is stretched is a taper roller having a flat central portion and tapered both end portions, and a flat portion of the tapered roller. Is shorter than the width of the conveyor belt.

According to a second aspect of the present invention, in the inkjet recording apparatus of the first aspect, a roller on the side of the transport roller and the transport driven roller that is apart from the recording head is the tapered roller.

According to a third aspect of the present invention, in the inkjet recording apparatus of the first or second aspect,
A configuration is provided in which a backup roller for maintaining the parallelism of the transport belt is provided opposite to the recording head.

According to a fourth aspect of the present invention, in the ink jet recording apparatus of any one of the first to third aspects, the width of the flat portion of the tapered roller is equal to or greater than the width of the maximum printing area.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a mechanism section showing an example of an ink jet recording apparatus according to the present invention.
FIG. 2 is an enlarged explanatory view of a main part of FIG. 1.

This ink jet recording apparatus comprises a carriage movable in the main scanning direction inside the recording apparatus main body 1, a recording head including an ink jet head mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. A paper feed cassette (or a paper feed tray) 4 capable of loading a large number of sheets 3 from the front side is detachably attached to a lower portion of the apparatus main body 1. A manual tray 5 is mounted on the front side so as to be openable and closable, and the paper fed from the paper feed cassette 4 or the paper 3 set in the manual tray 5 is taken in. Is recorded, and the sheet is discharged to the sheet discharge tray 6 mounted on the rear side. An upper cover 7 is mounted on the upper part so as to be openable and closable.

The printing mechanism 2 holds a carriage 13 slidably in a main scanning direction (a direction perpendicular to the paper surface of FIG. 1) by a main guide rod 11 and a sub guide rod 12 which are laterally mounted on left and right side plates (not shown). On the lower surface side of the carriage 13, a recording head 14 composed of an ink jet head having nozzles for discharging ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk) is ejected. The ink tank (ink cartridge) 15 for supplying each color ink to the recording head 14 is exchangeably mounted on the upper side of the carriage 5.

The recording head 14 may include a plurality of heads for ejecting ink droplets of each color arranged in the main scanning direction, or a single head having nozzles for ejecting ink droplets of each color. The used one may be used. The ink cartridge 15 is held on the carriage 13 by a cartridge holding lever 16.

On the other hand, in order to convey the paper 3 in the sub-scanning direction with respect to the printing position by the recording head 14, the paper 3 is electrostatically attracted and conveyed between the conveyance roller 21 and the conveyance driven roller 22. A gap adjusting member 24 is provided at a position facing the recording head 14 with the conveyance belt 23 interposed therebetween, in this case, on the back side of the conveyance belt 23.
Is displaceably disposed. A tip roller 25 that regulates the feed angle of the sheet 3 is pressed against the transport roller 21 via a transport belt 23 and disposed.

The transport roller 21 preferably has a diameter that does not separate the curvature, for example, a diameter of 30 mm or more, which secures the paper adhesion during double-sided printing, and the transport belt 23 has a volume resistance of 10 9 Ωcm to 10 12 Ωcm. It is preferable to use a medium resistor.

Further, as shown in FIG. 3, the transport driven roller 22 has a portion 22a having a constant outer shape at the center (this is referred to as a "flat portion"), and both ends have a smaller diameter toward the outside. And a tapered portion 22b formed in a tapered shape. Here, the width (length) L of the flat portion 22a of the transport driven roller 22 in the main scanning direction.
As shown in the figure, the width L1 is equal to or larger than the width of the maximum printing area in the main scanning direction in this recording apparatus, and is shorter than the width L2 of the transport belt 23 in the main scanning direction (L1 ≦ L <L).
2).

On the other hand, in order to feed the paper 3 from the paper feed cassette 4 onto the conveyor belt 23, a paper feed roller 26 and a friction pad 27 which separate and feed the paper 3 one by one,
A guide member 29 is provided to guide the fed sheet 3 to the intermediate roller 28 disposed in contact with the transport roller 21. The paper feed cassette 4 includes a bottom plate 32 and an extended bottom portion 33 that forms a sheet mounting surface together with the bottom plate 32 on the cassette body 31.
And the length of the sheet mounting surface can be selected by changing the mounting position of the extension bottom 33, so that the cassette body 3
Large-size papers exceeding one can be used. Further, an end fence 34 for regulating the rear end of the sheet is mounted on the extension bottom 33 so as to be movable in the lengthwise direction in a stepless manner.

In order to feed the paper 3 from the manual tray 5 to the transport belt 23, a pickup roller 35 for picking up the paper 3 from the manual tray 5, a feed roller 36 for feeding the paper 3, and a feed roller 37 , Paper 3
And a guide member 38 for guiding the intermediate roller 28 to the intermediate roller 28.

A guide member 41 for guiding the paper 3 in order to discharge the printed paper 3 to the paper output tray 6.
And a paper discharge roller 42 for feeding the paper 3 to the paper discharge tray 6
And a paper discharge driven roller 43.

Further, the paper 3 which has passed the printing position by the recording head 4 in order to once discharge the printed paper 3 out of the apparatus main body 1 and feed it to the conveyor belt 23 again to perform double-sided printing. A guide member 45 for guiding the sheet 3 obliquely downward between the discharge tray 6 and the paper feed cassette 4 is provided, and near the entrance between the guide member 45 and the guide member 41 on the discharge side, the paper 3 A first branch claw 46 for branching the discharge path is swingably provided.

In the vicinity of the end of the guide member 45,
A switchback roller 47 and a switchback driven roller 48 for discharging the paper 3 toward the upper surface of the paper feed cassette 4 outside the apparatus main body 1 and feeding the paper 3 into the apparatus main body 1 again are provided. This switchback roller 4
Reference numeral 7 denotes a normal rotation when the paper 3 having been printed on one side is conveyed in the discharge direction, a reverse rotation when the paper 3 is re-fed, and a rear end in the discharge direction of the paper 3 when the paper 3 is discharged. It is stopped at a predetermined timing in order to pinch.

Further, on the upstream side of the switchback roller 47 and the switchback driven roller 48 in the sheet discharging direction,
A second branching claw 49 for switching the transport path of the sheet 3 between a discharge path to the outside of the apparatus main body 1 and a path for re-feeding the sheet 3 into the apparatus main body 1 is provided swingably. In order to feed the paper 3 fed into the apparatus main body 1 by the reverse rotation of the paper to the transport belt 23, a guide member 51 for guiding the paper 3, a double-sided relay roller 52 for transporting the paper 3 and a double-sided relay roller driven roller 53 and transport roller 2
1 and a transport roller driven roller 54 that feeds the sheet 3 to the intermediate roller 28 following the first roller 1.

In the ink jet recording apparatus configured as described above, the recording head is fed while the paper 3 is fed from the paper feed cassette 4 to the transport belt 23 and the paper 3 is electrostatically attracted to the transport belt 23 and transported. An image is recorded on the paper 3 by ejecting ink droplets from 14 in accordance with the printed image.

At this time, the transport driven roller 22 on which the transport belt 23 is stretched is a tapered roller as shown in FIG. 3, and the flat portion 22a of the transport driven roller 22 has a width (length) L in the main scanning direction. The width L of the conveyor belt 23 in the main scanning direction
2 (L <L2), as shown in FIG. 3, both ends of the transport belt 23 face the tapered portions 22b and 22b of the transport driven roller 22, and the transport belt 23 rotates while the transport belt 23 rotates in the main scanning direction. , And can be prevented from approaching to one side or waving. Thereby, the sheet 3 is stably conveyed. The width (length) L of the flat portion 22a of the transport driven roller 22 in the main scanning direction is longer than the maximum printable area width L1 in the main scanning direction (L1 ≦ L).
Therefore, the flatness of the conveyor belt 23 in the printing area can be ensured.

As described above, the transport driven roller on which the transport belt is stretched is a taper roller having a flat central portion and a tapered end portion. Therefore, the deviation of the transport belt can be prevented, the paper can be transported stably and accurately, and the printing quality can be improved.

In this case, as the roller using the taper roller, instead of the conveyance driven roller 22 of the above embodiment,
Alternatively, the transport roller 21 may be used together with the transport driven roller 22. Conveying roller 21 and conveying driven roller 22
When one of the rollers is a tapered roller, it is preferable that the roller located at a position distant from the recording head be a tapered roller.

That is, when a taper roller is used, both ends in the main scanning direction of the transport belt 23 are deformed following the tapered portion 22b of the transport driven roller 22, as shown in FIG. Since it is not possible to say that there is no possibility of affecting the printing quality if both ends of the belt 23 are deformed, it is necessary to more reliably avoid the influence of the deformation of both ends of the transport belt 23 by using the recording head 14. It is preferable that the roller on the side away from the roller is a tapered roller.

Next, another embodiment will be described with reference to FIG. 4. In this embodiment, backup rollers 61, 61 for maintaining the parallelism of the transport belt 23 are provided at positions facing the recording head 14. I have. by this,
Conveyor belt 23 near the printing area by recording head 14
Can be maintained, and the paper can be transported more accurately and stably.

In each of the above-described embodiments, the transport driven roller (meaning a roller that is not driven to rotate by its own drive source)
However, when a plurality of transport driven rollers are provided, one or more of the rollers can be tapered rollers.

[0031]

As described above, according to the ink jet recording apparatus of the first aspect, at least one of the transport roller on which the transport belt is stretched and the transport driven roller has a flat central portion and both end portions. It is a tapered roller formed in a tapered shape, and the width of the flat portion of the tapered roller is shorter than the width of the transport belt, so that the transport belt can be prevented from shifting in the main scanning direction, and the paper can be stably formed. It can be transported accurately, and the printing quality is improved.

According to the ink jet recording apparatus of claim 2, in the ink jet recording apparatus of claim 1,
Since the roller on the side remote from the recording head in the transport roller and the transport driven roller is a taper roller,
It is possible to reliably prevent the influence of the deformation of the transport belt from affecting the printing area by the recording head.

According to the ink jet recording apparatus of the third aspect, in the ink jet recording apparatus of the first or second aspect, the backup roller for maintaining the parallelism of the transport belt is provided so as to face the recording head. The parallelism of the transport belt in the vicinity of the printing area can be reliably maintained, the paper can be transported stably and accurately, and the printing quality is improved.

According to the ink jet recording apparatus of the fourth aspect, in the ink jet recording apparatus of any one of the first to third aspects, the width of the flat portion of the tapered roller is equal to or larger than the width of the maximum printing area. The flatness of the transport belt in the printable area can be ensured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a mechanism section showing an example of an ink jet recording apparatus according to the present invention.

FIG. 2 is an enlarged explanatory view of a main part of FIG. 1;

FIG. 3 is an enlarged explanatory view of a conveyance driven roller of the recording apparatus.

FIG. 4 is an enlarged explanatory view of a main part explaining another example of the recording apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Device main body, 2 ... Printing mechanism part, 3 ... Paper, 4 ... Paper cassette, 5 ... Manual tray, 6 ... Discharge tray, 13 ... Carriage, 14 ... Recording head, 21 ... Conveying roller, 22
... Conveyance driven roller, 23 ... Conveyer belt, 61 ... Backup roller.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masumi Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Genichi Yasui 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd.

Claims (4)

[Claims] 1. An ink jet recording apparatus which conveys a sheet by a conveyance belt and discharges ink droplets from a recording head to print an image on the sheet, wherein the conveyance roller and the conveyance driven roller on which the conveyance belt is stretched are provided. At least one of the tapered rollers has a flat central portion and a tapered end portion, and the flat portion of the tapered roller has a width smaller than the width of the transport belt. 2. The ink jet recording apparatus according to claim 1, wherein a roller of the transport roller and the transport driven roller that is away from the recording head is the tapered roller. 3. The ink jet recording apparatus according to claim 1, further comprising a backup roller facing the recording head and maintaining a parallelism of the transport belt. 4. The ink jet recording apparatus according to claim 1, wherein a width of a flat portion of the tapered roller is equal to or larger than a width of a maximum printing area.