JPH07315642A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To convey recording paper without causing its deflection between recording means by forming a projection of a first roller in a direction in which a contact point with the recording paper moves outward in the lateral direction due to the rotation of the first roller. CONSTITUTION:A central part of recording paper supplied from a pair of register rollers to a printing unit in its lateral direction is sandwiched by the rollers between pulleys, both ends of the recording paper in the lateral direction are sandwiched by a conveyance belt 43 on the drive side and a conveyance belt 44 on the follow-up side, and the recording paper is conveyed in the P direction. At this time, a projection 830a of a deflection prevention roller 830 comes into contact with both ends of recording paper P1 in the lateral direction in a deflection prevention portion 810. Since peripheral speed of the deflection prevention roller 830 is slightly higher than the speed of the conveyance belt 43, the projection 830a moves outward in the lateral direction of the paper P1 while sliding on a surface of the paper P1. Tensile force is applied to the recording paper P1 in the (f) direction due to slide friction force. Consequently, it is possible to correct deflection of the paper P1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus used as an output device of a facsimile, a copying machine, a printer or a computer, and more particularly to an ink jet recording apparatus for printing on both sides of a recording sheet by an ink jet method. .

[0002]

2. Description of the Related Art Conventionally, an ink jet recording apparatus for ejecting ink from a nozzle of a recording head to print on a sheet has been put into practical use, and recently, an apparatus capable of printing on both sides of the sheet has been proposed. (JP-A-5-33003
7 publication). In this ink jet recording apparatus, the recording means is disposed so as to face both sides of the recording paper, the recording paper is conveyed between both recording means to eject ink, and immediately after printing, almost the entire surface of the recording paper is on the belt. It is designed to be sucked and transported. Further, conventionally, in such an ink jet recording apparatus, it is known that a high print quality can be obtained when the distance between the recording paper and the ink ejection surface of the recording means is set to about 1 mm or less.

[0003]

However, when the recording paper is conveyed between the two recording means, the recording paper is 1 m long.
If the sheet is bent by m or more, the sheet comes into contact with the ink ejection surface of one of the recording units. As a result, the printed image may flow, or the nozzle may be clogged to cause white streaks in the image, which may deteriorate the print quality. However, the above-mentioned conventional Japanese Patent Laid-Open No. 5-330037.
The recording apparatus described in the publication does not disclose a conveyance mechanism for conveying the recording sheet without bending between both recording means.

The present invention solves the above problems, and an object of the present invention is to provide an ink jet recording apparatus in which recording paper is conveyed between the recording means without bending in an apparatus for performing printing on both sides by the recording means. And

[0005]

In order to achieve the above object, the present invention discharges ink from nozzles of recording heads which are arranged opposite to each other with a required gap, to a conveying path passing through the gap. In an inkjet recording apparatus for recording an image on both sides of a recording sheet conveyed along the recording sheet, both ends of the recording sheet in the width direction are sandwiched by conveying belts from both sides, and the recording sheet is conveyed along the conveying path by rotation of the conveying belt. A sheet transporting means for transporting the sheet, and disposed along the transporting path,
A bending prevention means for preventing the recording paper from bending by applying a pulling force outward in the width direction to the recording paper, wherein the bending prevention means has a spiral projection formed on the peripheral surface thereof, A first roller disposed at least at one end side in the width direction at a position where the protrusion contacts the surface of the sheet;
Drive means for rotating the first roller at a peripheral speed higher than the rotation speed of the conveyor belt, and the protrusion of the first roller has a contact point with the recording sheet as the first roller rotates. It is formed so as to move outward in the width direction (claim 1).

Further, in the ink jet recording apparatus according to the first aspect, the ink jet recording apparatus is arranged at a position facing and in contact with the first roller on the side opposite to the recording sheet, and
The second roller is provided so as to be rotatable around the axis in the width direction (claim 2).

The second roller has a mirror image of the first roller (claim 3).

The surface of the second roller is formed of an elastic member (claim 4).

Further, in the ink jet recording apparatus according to any one of claims 1 to 4, a plurality of sets of opposed recording heads are provided along the conveying path, and the deflection preventing means is arranged between the adjacent gaps. It is provided (Claim 5).

Further, the conveying belt is stretched and retracted from the conveying path at a position where the bending preventing means is arranged (claim 6).

The ink jet recording apparatus according to any one of claims 1 to 6, further comprising moving means for moving the sheet conveying means and the deflection preventing means in the recording paper width direction according to the size of the recording paper. (Claim 7).

[0012]

According to the first aspect of the present invention, the recording sheet has a recording head of which both end portions in the sheet width direction are sandwiched by the conveyor belts from both sides and are arranged facing each other at the same position or at a slightly shifted position. It is transported to the gap. At this time, the contact point of the projection of the first roller disposed on at least one end side in the paper width direction moves outward in the width direction as the roller rotates. Moreover, since the peripheral speed of the first roller is higher than the rotational speed of the conveyor belt, the protrusions move while sliding on the surface of the recording paper. Therefore, the recording sheet is conveyed while being pulled outward in the width direction, so that the bending of the sheet is prevented.

According to the second aspect of the present invention, the projection of the first roller moves while sliding on the surface of the recording sheet in a state where the recording sheet is sandwiched by the first roller and the second roller. . Therefore, since the pulling force is applied to the recording paper outward in the width direction more reliably,
Deflection of the paper is surely prevented.

According to the third aspect of the invention, the projections of the first and second rollers move while sliding on the surface of the recording paper. Therefore, the pulling force outward in the width direction is applied to the recording sheet from both sides, so that the bending of the sheet is surely prevented.

According to the fourth aspect of the invention, the recording paper is pressed against the surface of the second roller by the protrusion of the first roller. At this time, the protrusion of the first roller moves while sliding on the surface of the recording sheet while a suitable pressing force is applied to the recording sheet by the elastic force of the second roller. Therefore, since the pulling force is applied to the recording paper outward in the width direction, the bending of the paper is surely prevented.

According to the fifth aspect of the invention, the sheet is conveyed while being pulled outward in the width direction between the gaps between the recording heads facing each other. The bending is surely prevented.

According to the sixth aspect of the invention, at the position where the recording sheet is conveyed while being pulled outward in the width direction, the width direction end portion of the recording sheet is not pinched by the conveyor belt, so that the recording sheet is bent. Is more reliably prevented.

According to the seventh aspect of the present invention, the sheet conveying means and the deflection preventing means are moved in the width direction of the recording sheet according to the size of the recording sheet, and the recording sheet of various sizes can be dealt with.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of the ink jet recording apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the external appearance of the apparatus of one embodiment. FIG. 2 is a diagram showing a schematic configuration of the inside of the device, (a) is a left side view, and (b) is a front view.

This device is, for example, a printer which prints character data or the like input from an external device. In FIG. 2 (b),
The right side is provided with a sheet storage unit including the sheet feeding cassettes 21 to 24, the left side is provided with a printing unit 4 for performing printing on both the front surface and the back side while conveying the recording sheet, and the sheets are transferred from the right side to the left side. A paper transport system 13 for transporting and a sorter 8 are disposed below the printing unit 4, respectively. The sorter 8 stores the printed recording paper by moving the bins 8a one by one in the horizontal direction by a spiral cam (not shown). In addition, the operation panel 1 is provided at a proper place on the surface of the device.
Also, a paper feed bypass unit 3 is provided.

The operation panel 1 includes an operation unit 1a (FIG. 9) provided with a paper size instruction key for manually instructing the size of the recording paper, a discharge recovery key for performing a discharge recovery operation, an LCD, an LED, etc. And a display unit 1b (FIG. 9) for displaying the setting contents. The paper feed bypass section 3 is for manually feeding paper by adjusting the width alignment mechanism 3a arranged on the surface of the apparatus to the paper width.

In the paper storage unit, paper feed cassettes 21 to 24 having different sizes capable of storing cut papers are stacked and arranged. In the paper feed cassettes 21 to 24, for example, A4 size recording paper is placed vertically in the paper feed cassette 21, A3 size is placed vertically in the paper feed cassette 22, and in the paper feed cassette 23 in the paper feed direction. The B4 size is oriented vertically,
The B5 size is horizontally stored in the paper feed cassette 24. The size and orientation of the paper stored in each cassette is not limited to the above.

The paper transport system 13 includes paper feed cassettes 21 to 21.
24 and the paper feed bypass unit 3, which are provided for feeding paper, feed rollers 31 to 34, 37, a pair of conveyance rollers for conveying the paper, a conveyance guide for guiding the conveyance paper, and an image recording timing. Correspondingly, a pair of registration rollers 38 for carrying the sheet are provided.

In the printing unit 4, a pair of drive side conveyor belt 43 and driven side conveyor belt 44 sandwich both ends of the recording sheet in the width direction, and convey the recording sheet along a chain line R in FIG. 2B. The printing mechanism is composed of four head units 5a and 5b, which are arranged on both sides of the conveyed paper so as to face each other, and a drying device 10 for drying ink on the surface of the printed paper.

First, the paper transport mechanism will be described with reference to FIGS. 3A and 3B are views showing the configuration of the printing unit 4, where FIG. 3A is a left side view and FIG. 3B is a front view. Figure 4
3A and 3B are schematic illustrations of the head holding mechanism of the head unit in FIGS. 3A and 3B for convenience of description. 5A and 5B are views showing the main part of the paper transport mechanism of the printing unit 4, where FIG. 5A is a left side view and FIG. 5B is a front view. In addition, in FIG. 3 (a), FIG. 4 (a) and FIG. 5 (a),
For convenience of description, the pulleys 83 and 84 are omitted.

The pair of drive side conveyor belts 43, 43 have an endless shape stretched around pulleys 80-84, idle rollers 85, 85 and pulleys 811-814 (FIG. 6A), respectively. The drive-side transport belt 43 is made of, for example, polyester mesh-free woven fabric to which chloroprene rubber is added, and the stretch is small and stable transport is possible. In addition, the pair of driven belts 44, 4
4 are pulleys 90 to 94 and idle roller 9 respectively.
5, 95 and the pulleys 821 to 824 (FIG. 6A) are stretched to form an endless shape. This driven conveyor belt 4
4 is made of urethane rubber, for example, and has a large expansion and contraction, and is formed of a material that easily follows the drive side transport belt 43. Further, the conveyor belts 43 and 44 have a width of, for example, 15 mm, and sandwich and hold, for example, a width of 5 mm at both ends of the recording paper in the width direction, and convey the recording paper.

The pulley 80 is fitted with the drive shaft 804 and is rotatably arranged on the conveyor belt moving plate 42 described later. The drive shaft 804 is rotatably supported by the side plates 11 and 12 fixed to the main body of the apparatus, has a D-shaped cross section, and both pulleys 80 rotate as the drive shaft 804 rotates. It is supposed to do. The gear 801 fixed to the drive shaft 804 is the gear 8 of the conveyor belt motor 803.
It is meshed with 02. Conveyor belt motor 803
Is a stepping motor, for example
The drive shaft 804 is rotationally driven via 801 to rotate the pulley 80 and rotationally drive the drive side transport belt 43.

The driven side conveyor belt 44 is driven by the frictional force with the driving side conveyor belt 43 to rotate. Further, the rotation amount and speed of the pulley 80, that is, the transport distance and transport speed of the recording sheet are controlled by the drive pulse supplied to the transport belt motor 803.

Pulley 81 and idle rollers 85, 85
Is a shaft 81a and a shaft 85 arranged between the side plates 11 and 12.
It is rotatably penetrated by a and 85a, and is rotatably arranged on the conveyor belt moving plate 42. Similarly, the pulleys 90 and 91 and the idle rollers 95 and 95
Is rotatably penetrated by the shafts 90a, 91a and the shafts 95a, 95a arranged between the side plates 11, 12, and
It is rotatably disposed on the conveyor belt moving plate 42. The idle rollers 85 and 95 are arranged to face the head unit 5 facing each other.
They are arranged above and below a and 5b to prevent the conveyor belts 43 and 44 from bending, and are driven and rotated by the frictional force with the conveyor belts 43 and 44.

Drive shaft 804, shaft 81a and shafts 85a, 8
5a and the shaft 90a, the shaft 91a, and the shafts 95a, 95a are arranged side by side with a required urging force in a direction in which they are close to each other with a required interval, and are stretched around each pulley and idle roller. The driven-side transport belt 43 and the driven-side transport belt 44 which have been separated from the pulleys 81 and 91 to the pulley 8
The contact is made with a required pressure over 0 and 90. Further, a roller 81b and a roller 91b (not shown) are fixedly installed at appropriate places in the central portions of the shaft 81a and the shaft 91a, respectively.
They are in contact with each other at a required pressure. This roller 81b,
The shaft 91b is rotatably arranged on the shafts 81a and 91a, and is rotated by the contact of the conveyed paper.

Here, the bending prevention portion 810 is shown in FIG.
This will be described with reference to FIGS. 4 and 6. FIG. 6A is an enlarged view of an essential part of FIG. 3B showing the bending prevention portion 810, and FIG. 6B is a view taken in the direction of arrow B in FIG. 6A showing the bending prevention roller.

The anti-deflection section 810 is provided at three locations along the paper transport path between the gaps between the head units 5a and 5b facing each other, and is composed of an anti-deflection roller 830, a driven roller 832, and the like. ing. Pulleys 811-8
14 is rotatably penetrated by a shaft arranged between the side plates 11 and 12, and is rotatably arranged on the conveyor belt moving plate 42 so as to be stretched and stretched.
However, they are arranged so as to be temporarily retracted from the paper transport path. Further, similarly, the pulleys 821 to 824 are similar to the side plates 1
The driven-side conveying belts 44, 44, which are rotatably penetrated by a shaft arranged between the first and the second portions 12 and are rotatably arranged on the conveying belt moving plate 42 and are stretched, are It is arranged so that it can be evacuated once.

The deflection preventing rollers 830 and 830 have spiral protrusions 830a formed on the peripheral surfaces thereof, the drive shafts 831 are fitted therein, and the rotation preventing rollers 830 and 830 are rotatably disposed on the conveyor belt moving plates 42 and 42 and driven. The side transport belts 43, 43 are arranged in the space retracted from the paper transport path. Protrusion 830a
In FIG. 6B, the left side anti-bending roller 830 is formed around the right screw and the right side is formed around the left screw. The drive shaft 831 is rotatably supported by the side plates 11 and 12, has a D-shaped cross section, and both rollers 830 rotate as the drive shaft 831 rotates.

The drive shaft 8 of the deflection preventing portion 810 at the above-mentioned three places
Each pulley 815 fixed to 31 and the deflection prevention motor 83
The pulley 834 fixed to the shaft of the belt 3 and the belt 835,
835 and 835 are stretched. Bending prevention motor 83
3 includes, for example, a stepping motor, and each belt 8
The deflection preventing roller 830 is rotationally driven by rotationally driving the drive shaft 831 via the rotary shaft 35. The rotation speed is controlled by the drive pulse supplied to the deflection preventing motor 833, and the peripheral speed is the conveyance of the recording sheet. It is set to be slightly higher than the speed.

The driven roller 832 has a columnar shape and is formed of an elastic member such as rubber or sponge, and has side plates 11 and 12.
It is rotatably pierced by a shaft 832a disposed therebetween, abuts against the deflection preventing roller 830, and is rotatably disposed on the conveyor belt moving plate 42 so as to be driven by the rotating deflection preventing roller 830. It has become.

With the above construction, when the drive shaft 804 rotates clockwise in FIG. 5B, the recording paper fed from the registration roller pair 38 to the printing unit 4 is transferred between the pulleys 81 and 91. Then, the center portion in the width direction is sandwiched by the rollers 81b and 91b, and both ends in the width direction are sandwiched by the drive side conveyor belt 43 and the driven side conveyor belt 44, respectively. Then, between the pulleys 81 and 91, the pulley 8
While being held by being sandwiched between the drive-side transport belt 43 and the driven-side transport belt 44 over the range 0 to 90, the P-direction (FIG. 5)
Be transported to.

At this time, in the anti-bending section 810, the projections 830a of the anti-bending roller 830 come into contact with both widthwise ends of the recording sheet P1 (two-dot chain line in FIG. 6B).
Here, the peripheral speed of the anti-bending roller 830 is equal to
Since the speed is slightly higher than the speed of 3, the protrusion 830a moves outward in the paper width direction while sliding on the paper surface. Due to this sliding frictional force, a pulling force is applied to the recording paper P1 in the f direction in FIG. 6B, so that the bending of the paper can be corrected.

Once the sheet is bent, the amount of bending increases as the sheet is conveyed, and the head units 5a, 5
This will contact the nozzle surface of b and stain the surface of the paper. However, by providing the bending prevention portion 810 that corrects the bending in the middle of the paper conveyance path, it is possible to prevent the recording paper from contacting the nozzle surfaces of the head units 5a and 5b, and it is possible to improve the print quality. .

Further, at the disposition position of the bending prevention portion 810,
Since the conveyor belts 43 and 44 are retracted, the deflection preventing rollers 830 can be arranged at the positions at both ends of the recording sheet in the width direction, and therefore the deflection is prevented without reducing the printable range of the recording sheet. be able to. In addition, since the recording sheet is not sandwiched by the transport belts 43 and 44 at the disposition position of the bending prevention portion 810, the bending of the recording sheet can be easily corrected.

In this embodiment, the bending prevention portion 810
Are disposed at three positions between the head units 5a and 5b, but when the amount of bending during sheet conveyance is small,
You may make it arrange | position at only one place or two places.

Further, the deflection preventing roller 830 may be arranged only on one end side in the paper width direction. At this time, the other end side does not require a configuration for retracting the conveyor belts 43 and 44. Even in this case, since the other end side of the recording sheet is held by the transport belts 43 and 44, the sliding frictional force of the protrusion 830a of the deflection preventing roller 830 applies a pulling force outward in the width direction, and thus the sheet is conveyed. Can be corrected.

Further, a mirror-shaped roller of the anti-bending roller 830 is disposed at the position of the driven roller 832, and this roller is driven by the anti-bending roller 830 or is rotated at the same peripheral speed. You may In this case, a pulling force is applied to the recording paper from both sides outward in the width direction, so that the bending of the paper can be more surely corrected.

Further, the pulley 82 is disposed diagonally above and to the left of the pulley 81 in FIG. 5B, and the pulley 92 is disposed diagonally above and right of the pulley 91 in FIG. Therefore, the pulley 8
The recording sheet fed in the P direction from the registration roller pair 38 can be reliably guided between the pulleys 81 and 91 by the conveyor belt between the rollers 81 and 91 and the pulleys 92 and 91.

Next, the moving mechanism of the conveyor belts 43 and 44 will be described with reference to FIGS. 4 and 7. FIG. 7 is a front view showing the shape of the transport belt moving plate 42.

The pair of conveyor belt moving plates 42, 42 are movably supported in the apparatus main body in the contact and separation directions,
The position of the conveyor belt can be changed according to the size of the recording paper.

The transport belt moving plate 42 is provided with shaft holes for rotatably holding the above-mentioned pulleys and idle rollers and square holes for avoiding the head units 5a and 5b and the drying device 10. At the same time, shaft holes 418 and 419 are formed at appropriate positions at both ends of the central portion.
The tubular bearing members 421a and 422a are fixedly installed. A stay 422 supported by the side plates 11 and 12 is fitted to the bearing member 422a, and a conveyor belt moving shaft 421 rotatably supported by the side plates 11 and 12 is fitted to the bearing member 421a. The conveyor belt moving plates 42, 42 are held by the stay 422 and the conveyor belt moving shaft 421.

The stay 422 of the bearing member 422a is slidable smoothly. The bearing member 421a and the conveyor belt moving shaft 421 have a female screw formed on the inner surface of the bearing member 421a, and a male screw formed over the required range on the outer surface of the conveyor belt moving shaft 421 to form a ball screw structure. There is. The screw of the conveyor belt moving shaft 421 is oriented in different directions with the central portion as a boundary, that is, FIG.
For example, the left side is formed with a right-hand thread and the right side is formed with a left-hand thread. In this case, the conveyor belt moving plates 42, 42 come close to each other when the conveyor belt moving shaft 421 rotates clockwise in FIG. 4B, and separate when the conveyor belt moving shaft 421 rotates counterclockwise.

The gear 423 fixed to the conveyor belt moving shaft 421 is meshed with the gear 424 of the belt moving plate motor 425. The belt moving plate motor 425 is composed of, for example, a stepping motor, and rotates the conveyor belt moving shaft 421 via gears 424 and 423. The conveyor belt moving plate 42,
42 can be moved according to the width of the recording paper. The rotation amount of the conveyor belt moving shaft 421, that is, the moving distance of the conveyor belt moving plates 42, 42 is controlled by the drive pulse supplied to the belt moving plate motor 425.

With the above-described structure, for example, when printing on A3 size recording paper, the conveyor belt moving plate 4 is used.
2 and 42 move to the positions shown by the solid lines in FIG.
In the case of A4 size, it moves to the position shown by the dotted line in FIG.

As described above, the pulleys and the conveyor belts can be integrally moved in the paper width direction shown by the arrow in FIG. 4 by the conveyor belt moving plates 42, 42 according to the width of the recording paper to be printed. Therefore, in correspondence with various paper sizes, both ends of the recording paper in the width direction are securely held by the drive side conveyor belt 43 and the driven side conveyor belt 44, respectively.
Paper can be conveyed.

A pair of drive side conveyor belts 4 are used as conveyor belts that are moved in the width direction according to the size of the recording paper.
It is also possible to use only one of the conveyor belts 3, 43 and the pair of driven side conveyor belts 44, 44. The other conveyor belts 43 and 44, which do not move according to the sheet size, may be moved to the outside of the head units 5a and 5b only during a capping operation or an idle discharge operation described later. In this case, the other conveyor belts 43 and 44 can shorten the required moving distance.

Next, the printing mechanism will be described with reference to FIG. The four head units 5a are in the shape of a rectangular parallelepiped, and are arranged on one surface side of the recording paper to be conveyed with a predetermined interval along the paper conveyance path, and the four head units 5b are arranged.
Has a rectangular parallelepiped shape similar to that of the head unit 5a, and is disposed on the other surface side across the sheet conveyance path at a position facing each head unit 5a.

Each head unit 5a is composed of a recording head 51a and a cap portion 52a, and
Each head unit 5b is composed of a recording head 51b and a cap portion 52b. Recording head 5
1a is arranged in parallel on the upper side of the cap portion 52a in FIG.
On the other hand, the recording head 51b has a cap portion 52b shown in FIG.
The recording head 51a and the cap portion 52b, and the recording head 51b and the cap portion 52a are arranged side by side on the middle and lower sides.
They are arranged at positions facing each other. The head unit 5a and the head unit 5b are movable between the contact position and the separation position in the contact and separation directions by a head holding mechanism described later, and are arranged in the contact position when printing is not performed. When printing is performed, they are arranged at a predetermined interval of 2 mm, for example.

The recording heads 51a and 51b are provided with nozzle rows in which, for example, minute diameter nozzles are arranged in a row at a predetermined pitch, and the recording paper is ejected from the nozzles by an ink ejecting mechanism provided in each nozzle and composed of, for example, a piezoelectric element. The image is printed on both sides of the recording paper by ejecting the ink toward. The size of the nozzle row is set to a value at which the short side of A3 size paper can be printed, for example.

The recording heads 51a and 51b eject yellow (Y), magenta (M), cyan (C), and black (BK) inks in this order from the upstream side in the paper transport direction P. These inks are sequentially ejected to perform color printing.

The nozzle array may be composed of a plurality of nozzle arrays in which the nozzles are arranged in a staggered manner. In addition, a head unit 5 including recording heads 51a and 51b for ejecting black (BK) ink
Only one of a and 5b may be provided so that black-and-white printing is possible.

Ink is supplied to each head unit 5a, 5b from an ink cartridge 14 (see FIG. 2) arranged in a proper place in the apparatus main body through an ink supply tube (not shown) made of, for example, a soft synthetic resin. . The ink cartridge 14 (see FIG. 2) is composed of four cartridges,
Each cartridge has yellow (Y), magenta (M),
Cyan (C) and black (BK) inks are enclosed, and ink is supplied from an ink needle attached to the base end of the ink supply tube.

The cap portions 52a and 52b are provided with caps made of, for example, rubber or soft synthetic resin, and the recording heads 51b and 51a are located at the close contact positions of the head units 5a and 5b.
Is performed to prevent solidification of the ink at the tip of the nozzle and invasion of foreign matter, bubbles, etc. into the nozzle.

A waste ink tube (not shown) is connected to the caps of the cap portions 52a and 52b, and suction means such as a pump 103 (FIG. 9) is provided in the waste ink tube. The pump 103 generates a suction force at the close contact position of the head units 5a and 5b, restores the meniscus formed at the nozzle tips of the recording heads 51a and 51b to a normal position, and causes air bubbles and foreign matters in the nozzles with ink. After the removal, the ejection recovery operation such as eliminating the defective ejection of the ink is performed. The ink sucked by the pump 103 is absorbed by the ink absorber made of urethane foam or the like inside the waste ink tank 18 (FIG. 2) disposed in the vicinity of the ink cartridge 14 (FIG. 2) via the waste ink tube. To be done.

During printing, the feeding of the recording paper to the printing unit 4 is temporarily stopped at a required interval, and the conveyor belt 4 is stopped.
As shown in FIG.
The recording heads 51a, 5 are retracted from between a and 51b.
By performing the idle discharge in which ink is discharged from all the nozzles from 1b toward the cap portions 52b and 52a, it is possible to prevent clogging of nozzles that are not used during printing or that are rarely used during printing. The idle discharge may be performed at the close contact position between the head units 5a and 5b.

Next, the head holding mechanism of the head unit will be described with reference to FIGS. 8A and 8B are views showing the configuration of the head holding mechanism, where FIG. 8A is a left side view and FIG. 8B is a front view.

Each head unit 5a is shown in FIG.
Required regions on the left and right sides are a pair of head moving plates 61a,
It is fixed to 61a and held integrally. On the other hand, similarly, in each head unit 5b, required regions on the left and right side surfaces are fixed to a pair of head moving plates 61b, 61b (not shown) and are integrally held.

The head moving plate 61a is a holding portion 611a formed by protruding rightward from the side plate 11 in FIG. 8 (a).
A through hole 62a is formed in the through hole 63a, and a through hole 63a is formed in a holding portion 612a formed so as to project leftward from the side plate 12. Similarly, the head moving plate 61b has a holding portion 611b formed to project rightward from the side plate 11 in FIG. 8A (front side in FIG. 8B) and the side plate 12.
Holding portion 612b (not shown) formed by protruding leftward from the
Through holes 62a (not shown) and 63a (not shown), respectively. A head moving shaft 62 rotatably supported by the apparatus body is fitted in the through hole 62a, while a head supporting shaft 63 supported by the apparatus body is fitted in the through hole 63a. The head moving plates 61a and 61b are held by the shafts 62 and 63.

The head support shaft 63 can be slid smoothly in the through hole 63a. The through hole 62a and the head moving shaft 62 have a ball screw structure in which a female screw is formed on the inner surface of the through hole 62a and a male screw is formed on the outer surface of the head moving shaft 62. Head movement axis 62
The screws of FIG.
In (b), for example, the left side has a right-hand thread and the right side has a left-hand thread. In this case, the head moving plates 61a and 61b
When the head moving shafts 62 rotate clockwise in FIG. 8A, they are separated from each other, and when they are rotated counterclockwise, they approach each other.

Gear 65 fixed to head moving shaft 62
Are meshed with the gear 66 of the head moving motor 64. The head moving motor 64 is composed of, for example, a stepping motor, and through the gears 66 and 65, the head moving shaft 6
2 is rotated. The amount of rotation of the head moving shaft 62, that is, the moving distance of the head moving plates 61a and 61b is controlled by the drive pulse supplied to the head moving motor 64.

The movement operation of the head units 5a and 5b having the above-described structure will be described with reference to FIGS.

When the printing operation is completed, first, the conveyor belt moving shaft 421 rotates counterclockwise in FIG. 3 (b), so that the conveyor belt moving plates 42, 42 respectively move as shown in FIG. 3 (a). Move in the direction of the arrow, and convey belts 43, 4
3 moves outward from between the head units 5a and 5b facing each other. Next, the head moving shaft 62 is rotated counterclockwise in FIG.
8A, the head units 5a and 5b are brought into close contact with each other for capping.

On the other hand, when starting the printing operation, first,
By rotating the head moving shaft 62 in the clockwise direction in FIG. 8A, the head moving plates 61a and 61b move in the directions opposite to the arrows in FIG. 8B, and the head units 5a and 5b are moved. Are separated and capping is released. Next, by rotating the conveyor belt moving shaft 421 in the clockwise direction by a required amount in FIG. 3B, the conveyor belt moving plates 42 and 42 respectively move in the opposite direction to the arrow in FIG. 3A. Then, the transport belts 43, 43 move to a position corresponding to the sheet size between the head units 5a, 5b facing each other.

In this way, by rotating the head moving shaft 62 to move the head moving plates 61a and 61b, the recording heads 51a and 5b of the head units 5a and 5b are moved.
Capping of 1b and its cancellation can be performed.

Next, the structure of the drying device 10 will be described with reference to FIG. The drying device 10 includes the head unit 5
It is composed of a fan 101 and a heater 102, which are arranged on both sides of a and 5b on the downstream side in the sheet conveying direction. For example, three fans 101 are arranged in parallel on both sides of the paper transport path as shown in FIG. 3, and blow the air toward the recording paper. The heater 102 has a heat source composed of a halogen lamp, a nichrome wire, etc., and has a sheet conveying path and a fan 10.
1 is disposed across the print width of the head units 5a and 5b. With the drying device 10 having such a configuration,
Warm air is blown onto both sides of the recording paper to dry the ink on the surface of the paper.

Next, the control configuration of this apparatus will be described with reference to the block diagram of FIG. In this device, each part operates based on an operation signal and an image signal input from an external device such as a personal computer.

The control unit 110 includes the CPU 120 and the storage unit 1.
11 and the like, and controls the operation of the entire apparatus in synchronization with the internal clock of the CPU 120. CPU1
Reference numeral 20 includes a recording control unit 121, a mechanism control unit 122, a display control unit 123, and the like, and the recording control unit 121 and the mechanism control unit 122 perform control operations in synchronization with each other. The storage unit 111 includes a ROM that stores a control program, a RAM that temporarily stores data, and the like. The interface (I / F) unit 112 is
It receives a signal input from an external device, and outputs an image signal to the recording control unit 121 and an operation signal such as a paper size to the mechanism control unit 122.

Based on the input operation signal, the mechanism control section 122 drives the sheet conveying system 13 such as the sheet feeding roller via the drive circuit 114 to cause the sheet feeding system to feed the sheet from the required sheet feeding cassette and to perform the recording. The drive of the sorter 8 is controlled every time printing on the paper is completed, and the paper is stored in the same bin or each bin. Further, a drive pulse is supplied to each motor such as the conveyor belt motor 803 via the drive circuit 114 to drive the motor. The drive circuit 114 includes a power supply unit, a transistor, and the like, and supplies a drive current to a drive system such as a motor based on a control signal from the mechanism control unit 122.

Further, the mechanism control section 122 determines whether or not the recording sheet is separated from the conveyor belts 43 and 44 based on the number of drive pulses supplied to the conveyor belt motor 803 and the elapsed time from the start of driving the registration roller pair 38. To do. Also,
The mechanism control unit 122 operates the fan 101 and the heater 102 until the last recording sheet to be printed from the start of printing on the recording sheet is separated from the transport belts 43 and 44. Incidentally, the separation of the recording paper from the conveyor belts 43 and 44 may be detected by disposing a paper sensor such as a reflection type optical sensor immediately below the pulley 80. Further, the mechanism control unit 122 causes the pump 10 to operate at a required interval while the power is on, when the discharge recovery key of the operation unit 1a is pressed, or when the power is turned on.
3 is operated to perform the ejection recovery operation.

When the size manually input by the paper size instruction key of the operation unit 1a is larger than the size input by the external device, the mechanism control unit 122 prints on the recording paper of the size key input. You may

The recording control section 121 outputs the input image signal to the drive circuits 113a, 11b of the head units 5a, 5b.
3b is serially transmitted. Drive circuit 113
Reference characters a and 113b are provided at appropriate positions in the head units 5a and 5b, respectively, and have a latch portion. The serial binary or multi-valued image signals for one line of the recording paper, for example, are temporarily latched, It is converted into a parallel signal.

Further, the recording control section 121 includes the drive circuit 11
The parallel signals converted by 3a and 113b are output to the corresponding piezoelectric elements of the recording heads 51a and 51b as pulse drive signals in synchronization with the mechanism control unit 122 to control ink ejection. For example, 2 of “0” and “1”
In the case of the value signal, for the signal of "1", a voltage is applied to the piezoelectric element during the pulse width thereof, and the hydraulic pressure rapidly increases, so that a fixed amount of ink is ejected from the nozzle. . The image signal for one line is sequentially transmitted at a predetermined cycle, whereby two-dimensional image recording is performed.

The cycle of ink discharge, that is, the cycle of signal output to the piezoelectric element is set within the range of the capabilities of the head units 5a and 5b, and the transport speed of the recording paper during printing, that is, the transport belt motor 803. The rotation speed of
It is set corresponding to the ink ejection cycle.

The display control unit 123 detects the presence or absence of paper in each paper feed cassette, the shortage of the remaining ink amount, etc., and displays the detection result on the display unit 1b. The remaining ink amount detection unit 115 detects the remaining amount of ink in the ink cartridge 14, and is displayed on the display unit 1b when the remaining amount falls below a predetermined level.

Next, the procedure of the printing operation will be described with reference to the flowchart of FIG. First, the head moving plate 6
1a and 61b move, capping is released, head units 5a and 5b are arranged at positions with a predetermined interval (step S1), and then the conveyor belt moving plates 42 and 4 are moved.
2 is moved, and the conveyor belts 43 and 44 are arranged at a predetermined position corresponding to the size of the recording paper on which printing is performed (step S2).

Next, when the paper feed roller or the like of the paper transport system 13 operates to feed paper from the required paper feed cassette, the leading edge of the paper reaches the registration roller pair 38, the paper is bent, and the leading edges of the paper are aligned. The paper transport system 13 is temporarily stopped, then the registration roller pair 38 is operated to feed the paper to the printing unit 4 and the drive of the transport belt 43 is started (step S3), and the drying device 10 is turned on. (Step S4).

Next, ink is ejected from each of the recording heads 51a and 51b to start printing (step S5),
While printing of this page is not completed (N in step S6
O), repeated. Then, when printing is completed (YES in step S6), it is determined whether or not the paper is separated from the conveyor belts 43 and 44 (step S7), and when it is determined that the paper is separated (YES in step S7), the next page It is determined whether or not the image signal data to be printed remains (step S8).

If the next data remains (YES in step S8), the sorter 8 is controlled (step S9) and the process returns to step S3. On the other hand, if the next data does not remain (NO in step S8), the conveyor belt 43 is stopped and the drying device 10 is turned off (step S10).

Next, the transport belt moving plates 42, 42 move to move the transport belts 43, 44 to the head unit 5a,
5b is retracted to the outside (step S11), and subsequently the head moving plates 61a and 61b move to move the recording heads 51a and 61a.
51b is capped (step S12).

As described above, since the conveying belts 43 and 44 that are movable in the width direction convey the recording paper while sandwiching and holding both ends in the width direction of the recording paper, the recording paper of various sizes can be surely transferred to the head unit. It is possible to carry out double-sided printing by conveying between 5a and 5b.

[0086]

As described above, according to the first aspect of the present invention, the contact point of the spiral protrusion of the first roller with the recording sheet moves outward in the width direction as the roller rotates. Since the peripheral speed of the first roller is made higher than the rotational speed of the conveyor belt, the recording paper is conveyed while being pulled outward in the width direction, so that the recording paper can be conveyed into the gap of the recording head without bending. You can Therefore, an image with high print quality can be obtained.

According to the second aspect of the present invention, the first sheet of recording paper is sandwiched between the first roller and the second roller,
Since the protrusion of the roller moves while sliding on the surface of the recording paper, it is possible to more reliably apply a pulling force to the recording paper outward in the width direction, and thus it is possible to reliably prevent the bending of the paper. it can.

According to the third aspect of the invention, since the second roller is a mirror image of the first roller, the pulling force outward in the width direction is applied to the recording sheet from both sides. Therefore, the bending of the paper can be more reliably prevented.

Further, according to the invention of claim 4, since the surface of the second roller is formed by the elastic member, a state in which a suitable elastic force is applied to the recording sheet by the projection of the first roller and the second roller Since the projection moves while sliding on the surface of the recording paper, the bending of the paper can be reliably prevented.

Further, according to the fifth aspect of the invention, since the deflection preventing means is provided between the gaps of the recording heads facing each other, the deflection of the recording paper is surely prevented between the recording heads on which ink is ejected. can do. Therefore, an image with high print quality can be obtained.

Further, according to the invention of claim 6, at the position where the deflection preventing means is disposed, the widthwise end portion of the recording sheet is not held by the conveyor belt, so that the deflection of the recording sheet is corrected. It can be done easily.

Further, according to the invention of claim 7, since the sheet conveying means and the deflection preventing means are moved in the width direction of the recording sheet, the recording sheets of various sizes can be bent in the gap of the recording head. It can be conveyed without any trouble, and an image with high print quality can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing the external appearance of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of the inside of the apparatus, (a) is a left side view, and (b) is a front view.

3A and 3B are diagrams showing a configuration of a printing unit 4, wherein FIG. 3A is a left side view and FIG. 3B is a front view.

4A and 4B are schematic views of the head holding mechanism of the head unit shown in FIGS. 3A and 3B, for convenience of description.

5A and 5B are diagrams showing a main part of a sheet conveying mechanism of the printing unit 4, wherein FIG. 5A is a left side view and FIG. 5B is a front view.

FIG. 6A is an enlarged view of a main part of FIG. 3B showing a bending prevention portion 810, and FIG. 6B is a view taken in the direction of arrow B in FIG.

FIG. 7 is a front view showing the shape of a conveyor belt moving plate.

8A and 8B are diagrams showing a configuration of a head holding mechanism, in which FIG. 8A is a left side view and FIG. 8B is a front view.

FIG. 9 is a block diagram showing a control configuration.

FIG. 10 is a flowchart showing a procedure of a printing operation.

[Explanation of symbols]

 1a Operation part 1b Display part 4 Printing unit 5a, 5b Head unit 10 Drying device 11, 12 Side plate 13 Paper conveying system 38 Registration roller pair 42 Conveying belt moving plate 43 Driving side conveying belt 44 Driven side conveying belt 51a, 51b Recording head 52a , 52b Cap part 62 Head moving shaft 64 Head moving motor 80-84, 90-94 Pulley 85, 95 Idle roller 101 Fan 102 Heater 103 Pump 110 Control part 111 Storage part 113a, 113b, 114 Drive circuit 115 Ink remaining amount detection part 120 CPU 121 Recording control unit 122 Mechanism control unit 123 Display control unit 421 Conveyor belt moving shaft 425 Belt moving plate motor 803 Conveying belt motor 804, 831 Drive shaft 833 Bending prevention motor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B41J 13/08 B65H 5/02 N // B41J 3/54 (72) Inventor Shizushi Kado Osaka 1-22 Tamatsukuri, Chuo-ku, Mita Within Mita Kogyo Co., Ltd. (72) Inventor Kenichi Satake 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Co., Ltd. (72) Inventor Hiromi Kosaka Osaka-shi Chuo 1-22-28 Tamazukuri Mita Kogyo Co., Ltd. (72) Inventor Koichi Baba 1-2-22 Tamatsukuri Chuo-ku, Osaka City Mita Kogyo Co., Ltd. (72) Inventor Masayuki Ishii Tamatsukuri, Chuo-ku Osaka 1-228 Mita Engineering Co., Ltd. (72) Inventor Yoshiko Kawachi 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Engineering Co., Ltd.

Claims (7)

[Claims] 1. Ink jet recording in which ink is ejected from nozzles of recording heads which are arranged facing each other with a required gap, and images are recorded on both sides of a recording sheet conveyed along a conveying path passing through the gap. In the apparatus, both ends in the width direction of the recording paper are sandwiched from both sides by a conveyor belt, and the conveyor belt rotates to convey the recording paper along the conveyor path. Is
A bending prevention means for preventing the recording paper from bending by applying a pulling force outward in the width direction to the recording paper, wherein the bending prevention means has a spiral projection formed on the peripheral surface thereof, A first roller disposed at least at one end side in the width direction at a position where the protrusion contacts the surface of the sheet;
Drive means for rotating the first roller at a peripheral speed higher than the rotation speed of the conveyor belt, and the protrusion of the first roller has a contact point with the recording sheet as the first roller rotates. An ink jet recording apparatus, which is formed so as to move outward in the width direction. 2. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is disposed at a position facing and in contact with the first roller on the opposite surface side of the recording sheet, and is rotated around the axis in the width direction. An inkjet recording apparatus comprising a second roller movably arranged. 3. The ink jet recording apparatus according to claim 2, wherein the second roller has a mirror image of the first roller. 4. The ink jet recording apparatus according to claim 2, wherein the surface of the second roller is formed of an elastic member. 5. The ink jet recording apparatus according to claim 1, further comprising a plurality of sets of opposed recording heads along the conveyance path, wherein the deflection preventing means is disposed between the adjacent gaps. An ink jet recording apparatus characterized by being provided. 6. The conveying belt according to claim 1, wherein the conveying belt is stretched by retracting from the conveying path at a position where the bending preventing means is arranged. Inkjet recording device. 7. The ink jet recording apparatus according to claim 1, further comprising a moving unit that moves the sheet conveying unit and the deflection preventing unit in the recording sheet width direction according to the size of the recording sheet. An inkjet recording apparatus characterized by the above.