JP2000238925A - Ink jet recording device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To stably convey paper with a simple configuration. A transport roller (2) for stretching a transport belt (23).
1, a pressure roller 25 made of an elastic material is disposed at a position facing the sheet conveying belt 23 therebetween.

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 which conveys a sheet by using a conveying belt.

[0002]

2. Description of the Related Art An ink jet recording apparatus used as an image recording apparatus (image forming apparatus) such as a printer, a facsimile, and a copying apparatus discharges ink droplets from nozzles (ejection ports) of an ink jet head to record paper (image). This means that the image is recorded on paper.) If the relative positional relationship between the recording head and the paper deviates, the image quality deteriorates. It will need to be transported.

[0003] In addition, the ink jet recording apparatus tends to undulate the paper during printing because ink droplets are adhered to the paper for recording. When the gap between the head and the head is varied and the image is disturbed or when the waving becomes large, the paper and the head come into contact with each other to cause an abnormal image or damage to the head.

Therefore, conventionally, for example, Japanese Unexamined Patent Publication No.
As described in Japanese Patent Application Publication No. 8 (1996) -108, there is known an apparatus in which a sheet is transported using a transport belt. And
In an ink jet recording apparatus using such a belt transport device, as described in JP-A-7-137877, an electrode having a comb-tooth pattern is arranged on the back side of the transport belt, and the There is a printer in which a bias voltage is applied to generate an electrostatic attraction force to suction and transport a sheet. Also, JP-A-4-31070
As described in Japanese Patent Application Laid-Open Publication No. H10-209, there is also known an apparatus in which a uniform belt and paper are charged, electrostatically adsorbed, and transported.

[0005]

As described above, in the conventional belt conveying apparatus, various measures have been taken to increase the electrostatic attraction force in order to stably convey the paper. In the case where the paper is electrostatically attracted by applying a bias voltage to the transport belt and generating an electrostatic attraction force by the electrodes of the comb pattern arranged on the back side of the transport belt, the driving load of the transport belt is reduced. However, it is not possible to increase the attraction force to the paper with a simple configuration, for example, the size becomes large.

SUMMARY OF THE INVENTION 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 improving the attraction of a sheet with a simple configuration and stably conveying the sheet. I do.

[0007]

According to a first aspect of the present invention, there is provided an ink jet recording apparatus, comprising: a roller which is opposed to a roller on an upstream side in a sheet conveying direction; A configuration in which a pressure roller that comes into pressure contact is arranged.

According to a second aspect of the present invention, in the inkjet recording apparatus of the first aspect, a nip formed by the transport belt and the pressure roller has a width of 1 mm.
The configuration described above was adopted.

According to a third aspect of the present invention, in the inkjet recording apparatus of the first or second aspect,
The pressure roller is arranged within a range of 90 ° in a direction opposite to the roller rotation direction from a position where the conveyance belt separates from a roller on the upstream side in the sheet conveyance direction on which the conveyance belt is stretched.

According to a fourth aspect of the present invention, there is provided an ink jet recording apparatus, wherein a pressure roller, which presses and contacts a roller on the upstream side in the paper transport direction, is disposed between the two rollers for stretching the transport belt. A bias voltage is applied between the side roller and the pressure roller to perform constant current control.

According to a fifth aspect of the present invention, in the ink jet recording apparatus of the fourth aspect, the resistance between the roller on the upstream side in the sheet conveying direction and the pressure roller is in the range of 10 ⁴ to 10 ¹² Ω. Configuration.

According to a sixth aspect of the present invention, in the ink jet recording apparatus of any one of the first to fifth aspects, the roller on the upstream side in the sheet conveying direction is a driving roller that is rotationally driven.

According to a seventh aspect of the present invention, in the ink jet recording apparatus according to any one of the first to sixth aspects, the pressure roller is longer than a maximum sheet width and rotates.

[0014]

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 a schematic configuration diagram illustrating a main part of FIG. 1.

This ink jet recording apparatus includes 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. The printing mechanism 2 and the like are stored.

A paper cassette (or a paper tray) 4 capable of stacking a large number of sheets 3 can be detachably attached to the lower part of the apparatus main body 1 from the front side. On the front side, a manual feed tray 5 is mounted 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 feed tray 5 is taken in. After a required image is recorded by the printing mechanism 2, The paper is discharged to the paper 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 in FIG. 1) by a main guide rod 11 and a sub guide rod 12 which are horizontally 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, as shown in FIG.
In order to transport the paper 3 in the sub-scanning direction with respect to the printing position of the paper 4, the paper 3 is electrostatically attracted and transported between the transport roller 21, which is a rotationally driven drive roller, and the transport driven roller 22. A transfer belt 23 is stretched and disposed, and a print receiving member 24 is provided at a position facing the recording head 14 with the transfer belt 23 interposed therebetween.

A pressure roller made of an elastic material is provided at a position opposite to the transport roller 21 which is the upstream roller in the paper transport direction of the two rollers for stretching the transport belt 23 with the paper transport belt 23 interposed therebetween. 25 are arranged. The pressure roller 25 is disposed within a range of 90 ° in a direction opposite to the rotation direction of the transport roller 21 from a position where the transport belt 23 is separated from the transport roller 21 as a starting point.

The pressure roller 25 is longer than the maximum usable paper width (length in the direction perpendicular to the paper surface in FIG. 1) and rotates with the transport belt 23. Further, the nip formed between the pressure roller 25 and the transport belt 23 is set to be 1 mm or more.

Here, it is preferable that the transport roller 21 has a diameter that ensures the paper adhesion during double-sided printing and does not separate the curvature, for example, a diameter of 30 mm or more. Further, the transport driven roller 22 has a diameter of 16 mm or less so that the sheet can be separated in curvature. Further, the conveyor belt 2
3 is a medium resistance member having a volume resistance of 10 @ 8 to 10 @ 11 .OMEGA., So that charge-up due to paper conveyance can be prevented and the conveyance property can be secured.

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 discharge 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 is used to discharge the printed paper 3 once out of the apparatus main body 1 and then feed it again to the conveyor belt 23 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 terminal 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.

As described above, in this ink jet recording apparatus, the transport belt 2 faces the transport roller 21.
Since the pressure roller 25 that presses through the paper 3 is provided, the adhesion of the paper 3 to the transport belt 23 is improved, and the paper 3 can be transported stably. In this case, the nip formed by the transport belt 23 and the pressure roller 25 is 1 mm.
By doing so, the paper 3 is transported more reliably to the transport belt 23.
Can be adhered to.

Further, the pressure roller 25 is
Is disposed within a range of 90 ° in a direction opposite to the rotation direction of the transport roller 21 from a position where the paper 3 is separated from the transport roller 21, so that the sheet 3 can be more securely brought into close contact with the transport belt 23, and defective transport Can be prevented. In addition, by making the pressure roller 25 longer than the maximum usable paper width and rotating with the conveyor belt 23, it is possible to reduce the cost and stabilize the conveyance. Also, the transport roller 2
By using 1 as a drive roller, the transportability is stabilized and high image quality can be achieved.

Next, another embodiment of the present invention will be described with reference to FIG. Here, a bias power source (power pack) PP for applying a bias voltage to the transport belt 23 is provided, and the bias voltage from the bias power source PP is applied to the transport roller 21 which is an electrode member provided on the back side of the transport belt 23. And a pressure roller 25 that presses the sheet 3 against the conveyor belt 21 to apply a bias power P
P controls the constant current so that the current I1 flowing into the transport roller 21 and the current I2 flowing from the pressure roller 25 become constant.

Therefore, when the paper thickness of the paper 3 changes, the bias voltage applied from the bias power supply PP to the transport roller 21 is changed, for example, when the paper thickness of the paper 3 becomes thicker (this is because the resistance is increased). By increasing the voltage, the flowing current is controlled to be constant. As a result, the charge on the transport belt 23 and the paper 3 becomes constant,
Even if the paper 3 becomes thicker, the electrostatic attraction force of the transport belt 23 can be ensured.

In this case, the conveying roller 21 and the pressure roller 2
By setting the resistance value between 5 and 10 to be 10 ⁴ to 10 ¹² Ω, leakage can be prevented, the conveyor belt 23 can be charged uniformly, and an attraction force corresponding to the sheet thickness can be secured. Thus, the paper can be stably and reliably conveyed.

[0034]

As described above, according to the ink jet recording apparatus of the first aspect, of the two rollers on which the conveyor belt is stretched, the roller which comes into pressure contact with the roller on the upstream side in the sheet conveyance direction. Since the pressure roller is provided, it is possible to improve the attraction force of the sheet to the transport belt and perform stable transport.

According to the ink jet recording apparatus of claim 2, in the ink jet recording apparatus of claim 1,
The width of the nip formed by the conveyor belt and the pressure roller is 1m
m or more, it is possible to further improve the attraction force of the sheet to the transport belt and perform stable transport.

According to the ink jet recording apparatus of the third aspect, in the ink jet recording apparatus of the first or second aspect, a position at which the transport belt separates from a roller on the upstream side in the paper transport direction on which the transport belt is stretched is used as a starting point. Since the pressure roller is disposed within a range of 90 ° in the direction opposite to the roller rotation direction, it is possible to more reliably improve the attraction force of the paper to the transport belt and perform stable transport.

According to the ink jet recording apparatus of the present invention, of the two rollers on which the transport belt is stretched, a pressure roller which is in pressure contact with the roller on the upstream side in the paper transport direction is arranged, and The bias voltage is applied between the roller on the upstream side in the direction and the pressure roller to control the constant current, so that the attraction force can be improved according to the paper thickness.
Stable conveyance can be performed.

According to the ink jet recording apparatus of claim 5, in the ink jet recording apparatus of claim 4,
Since the resistance value between the roller on the upstream side in the paper conveyance direction and the pressure roller is in the range of 10 ⁴ to 10 ¹² Ω,
Leakage is prevented, uniform charging can be performed, and more stable conveyance can be performed.

According to the ink jet recording apparatus of claim 6, in the ink jet recording apparatus of any one of claims 1 to 5, the roller on the upstream side in the sheet conveying direction is a driving roller that is driven to rotate. The transportability can be stabilized, and high image quality can be achieved.

According to the ink jet recording apparatus of the seventh aspect, in the ink jet recording apparatus of any one of the first to sixth aspects, the pressure roller is longer than the maximum sheet width;
Because of the configuration of the rotation, the conveyance can be stabilized at low cost, and high image quality can be achieved.

[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 a schematic configuration diagram showing a main part of the recording apparatus.

FIG. 3 is a schematic configuration diagram showing another embodiment of the present invention.

[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 ... conveyor belt, 24 ... printing receiving member, 25 ... pressure roller.

Continued on the front page (72) Inventor Masato Yokoyama 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Satoshi Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Masaki Horiya 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C056 HA29 3F049 AA06 CA13 DA12 EA02 LA07 LB03 3F101 LA07 LB03

Claims (7)

[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 two rollers for stretching the conveyance belt are provided. An ink jet recording apparatus, comprising a pressure roller which is in pressure contact with a roller on the upstream side in the paper transport direction. 2. The ink jet recording apparatus according to claim 1, wherein a width of a nip formed by the transport belt and a pressure roller is 1 mm or more. 3. The ink jet recording apparatus according to claim 1, wherein a position at which the transport belt separates from a roller on the upstream side in the paper transport direction on which the transport belt is stretched is set as a starting point, in a direction opposite to the roller rotation direction. An ink jet recording apparatus, wherein the pressure roller is disposed within a range of degrees. 4. 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 two rollers for stretching the conveyance belt are provided. A pressure roller that is in pressure contact with the roller on the upstream side in the paper transport direction is arranged,
An ink jet recording apparatus, wherein a bias voltage is applied between a roller on the upstream side in the sheet conveying direction and a pressure roller to perform constant current control. 5. The ink jet recording apparatus according to claim 4, wherein a resistance value between the roller on the upstream side in the sheet conveying direction and the pressure roller is in a range of 10 ⁴ to 10 ¹² Ω. Inkjet recording device. 6. The ink jet recording apparatus according to claim 1, wherein the upstream roller in the sheet transport direction is a driving roller that is driven to rotate. 7. The ink jet recording apparatus according to claim 1, wherein the pressure roller is longer than a maximum sheet width and rotates together.