JPH07314821A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To prevent the deflection of a recording sheet from being input to a recorder (between conveying belts) as it is in a sheet feeding type in which the sheet is intentionally deflected at the inlet side of the recorder. CONSTITUTION:On the premise of employing a double end feeding type for conveying a recording sheet P by holding the width direction both ends of the sheet P between a drive belt 2 and a driven belt 3, the inlet roller 5 of the belt 2 is formed in a drum state in which a central part is expanded as a deflection stopping roller while deflecting the sheet P to the belt 2 side by a deflection guide plate 4, thereby introducing the sheet P into a recorder while straightening the sheet P in a flat direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a facsimile, a copying machine,
The present invention relates to an inkjet recording device used as an output device of a computer.

[0002]

2. Description of the Related Art An ink jet recording apparatus has a recording section
A recording head provided with a large number of nozzles (ink ejection ports) is provided, and an image is recorded by ejecting ink from the nozzles onto a recording sheet conveyed by a sheet conveying unit.

Conventionally, as a sheet conveying means in this ink jet recording apparatus, generally, Japanese Patent Laid-Open No. 1856/1991.
A belt is used as disclosed in both No. 61 and JP-A-5-330037.

Further, as a belt conveying method suitable for a double-sided recording method (a method of recording images on both sides of a recording sheet), both ends in the sheet width direction are sandwiched between a pair of narrow conveying belts. It is conceivable to adopt a double-sided feeding method in which the paper is conveyed by.

According to this method, almost the entire area of both sides of the sheet is opened, so that the recording heads on both the front and back sides can be arranged opposite to each other at the same position in the sheet conveying direction. For this reason, there is an advantage that the recording unit can be made smaller than the case where the recording heads on both the front and back sides are displaced in the paper transport direction.

[0006]

However, in this case,
The following problems arise.

A sheet feeding roller is provided at the entrance side of the recording section as a means for feeding the sheet to the recording section. However, it is technically difficult to completely synchronize the sheet feeding roller with the conveying belt of the recording section. Therefore, if the paper delivery structure between the paper feed roller and the transport belt is designed on the premise of synchronization, there is a high possibility that a transport trouble will occur due to a synchronization failure.

Therefore, it is considered a good idea to intentionally provide a speed difference between the paper feed roller and the conveyor belt and design the conveyor structure on the basis of this speed difference.

In this case, however, the paper feed speed of the paper feed roller (hereinafter referred to as the paper feed speed) is set lower than the paper transport speed of the conveyor belt (hereinafter referred to as the belt carry speed), and the paper feed roller brakes. If the paper is drawn into the conveyor belt while applying the paper, the paper conveyance speed increases at the moment the paper comes off the paper feed roller, and the image is disturbed.

Therefore, on the contrary, a method of setting the paper feeding speed higher than the belt conveying speed and delivering the paper while flexing the paper between the paper feeding roller and the conveyor belt (hereinafter referred to as the flexible paper feeding method It is more desirable to take

However, in this case, depending on the speed difference, the sheet may be pushed between the conveyor belts in a bent state.

In this case, since the gap between the recording heads arranged opposite to each other is small (about 2 mm), the paper comes into contact with the nozzles of the recording head and the image flows, or the nozzles are clogged and the image white streaks occur. It causes recording failure such as occurrence of.

In view of the above points, the present invention adopts the both-end feeding method and the flexible sheet feeding method, and the flexure of the sheet at the sheet delivering portion between the sheet feeding roller and the recording section is the same as that of the recording section (conveying belt). The present invention provides an ink jet recording apparatus that can prevent the ink from being taken into the space.

[0014]

According to a first aspect of the present invention, there is provided a recording section provided with a belt conveying means and a recording head,
The recording paper sent to the recording unit by the paper feed roller
In an inkjet recording apparatus for recording an image by ejecting ink from nozzles of a recording head onto the same sheet while being conveyed by the belt conveying means, the belt conveying means serves as the belt conveying means on both sides in the width direction of the recording sheet. A pair of front and back conveyance belts that convey at a lower speed than the paper feed roller with both ends in the direction sandwiched from both sides.
A plurality of rollers including both entrance rollers arranged at the paper entrance are provided around which the conveyor belts are stretched, and the bending direction of the recording paper is kept constant between the paper entrance of the belt carrying means and the paper feed roller. In addition to providing the bending guide means for restricting to the above, the above-mentioned entrance roller of the conveying belt in the sheet bending direction by the bending guide means is formed in a drum shape with a bulged central portion as a bending prevention roller. is there.

According to a second aspect of the present invention, in the structure of the first aspect, one of the two conveyor belts is a driving belt driven by a motor, and the other is a driven belt which contacts the driving belt and transmits a rotational force. And the bending guide means is configured to bend the sheet toward the driving belt, and the entrance roller of the driving belt is a bending prevention roller.

According to a third aspect of the present invention, in the structure of the first or second aspect, at least one of the conveyor belts on both sides in the sheet width direction is supported as a movable conveyor belt so as to be movable in the sheet width direction. A belt moving means for moving the movable conveyance belt in the paper width direction together with the roller according to the paper size is provided.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the inlet rollers of the conveying belts on both sides in the paper width direction are provided on a common roller shaft, and the roller shaft is provided between the two inlet rollers. A plurality of intermediate guide rollers that rotate while contacting the recording paper are provided at intervals in the axial direction.

According to a fifth aspect of the present invention, in the structure of the third aspect, the intermediate guide rollers of the fourth aspect are provided so as to be movable in the paper width direction, and the intermediate guide rollers are provided between the intermediate guide rollers and at both ends. A coil spring is provided between the inlet roller and the inlet roller to push the rollers in a direction in which they are separated from each other.

According to a sixth aspect of the present invention, in the structure of the fourth or fifth aspect, each intermediate guide roller that contacts the front and back side of the recording sheet and each intermediate guide roller that contacts the opposite side are arranged in the sheet width direction. It is provided in a staggered arrangement with misalignment.

[0020]

According to the above construction, the recording paper is delivered between the paper feed roller and the recording portion (conveying belt) by the both-ends feeding method and the flexible paper feeding method, and the flexure guide means bends the paper at the delivery portion. The direction is regulated constantly.

At the entrance of the recording portion, the widthwise both ends of the recording paper are flattened by being pressed against the outer peripheral surface (convex curved surface) of the drum-shaped anti-deflection roller through the conveyor belt. In response to this, the bending-preventing action prevents the bending of the sheet at the delivery portion from entering the recording portion. This was clarified by the inventor's experiment.

Further, the structure of claim 2 is also obtained by an experiment, and in the structure in which one side of the front and back sides is a driving belt and the other side is a driven belt, the inlet roller of the driving belt is a deflection preventing roller, so that the driven belt is driven. As compared with the case where the belt entrance roller is an anti-deflection roller, the effect of anti-deflection of the paper becomes more reliable.

On the other hand, according to the third aspect of the present invention, the interval between the conveyor belts on both sides in the paper width direction is changed according to the paper size, that is, the both-end feeding method is adopted for each size paper and recording is performed. It is possible to obtain the effect of preventing the sheet from bending at the portion.

Further, according to the structure of claim 4, the plurality of intermediate guide rollers sandwich the sheet between the belts on both sides in the sheet width direction to provide a conveying force, so that the sheet is flat in the intermediate portion. Since it is corrected, the anti-deflection effect becomes more reliable.

In this case, according to the structure of the sixth aspect, since the intermediate guide rollers are arranged in a zigzag manner, so-called stiffness is given to the sheet, and thereby the anti-deflection effect is enhanced.

Further, according to the structure of claim 5, in the structure of claim 3 in which the distance between the two side conveyor belts can be changed according to the sheet size, the moving force of the movable conveyor belt is transmitted to each intermediate guide roller via the coil spring. Then, the guide roller automatically moves together with the movable conveyance belt.

[0027]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the recording section of the ink jet recording apparatus according to this embodiment.

This recording unit conveys a recording sheet (hereinafter, simply referred to as a sheet) P sent from a sheet feeding section (not shown) via registration rollers 1 and 1 on a sheet moving line R from the upper side to the lower side in the drawing. Both the front side and the back side recording heads B1 and B2 provided on both sides of the transport mechanism A and the sheet moving line R for double-sided recording (here, both recording heads B1 and B2 are connected to the sheet moving line R for color recording). The case where four sets are provided along with each other is illustrated), and a drying device C for drying the recorded paper P by blowing warm air from a heater and a fan.

The sheet conveying mechanism A is provided with both driving and driven belts 2 and 3 arranged on both sides of the sheet moving line R, and the rotational force of the driving belt 2 driven by a motor (not shown) is applied to the driven belt 3. Both belts 2 and 3 are rotated at the same time by being transmitted at the portions in mutual contact.

The drive and driven belts 2 and 3 are
As shown in FIGS. 3 and 4, the sheets P are arranged on both sides in the width direction, and both ends of the sheet P in the width direction are sandwiched between the two belts 2 and 3 and are conveyed by a double-side feed method.

Here, the belt conveying speed is set lower than the paper feeding speed, and due to this speed difference, the paper P is sent to the recording portion (between the belts 2 and 3) while being bent as shown in FIG.

A slightly curved plate-shaped bending guide plate 4 is provided between the registration rollers 1 and 1 and the recording portion.

The bending guide plate 4 is provided from the driven belt 3 side to the driving belt 2 side, and the sheet P is pushed to the driving belt 2 side by the guiding plate 4 so that the bending direction thereof becomes the driving belt 2 direction. Regulated.

The drive belt 2 includes an entrance roller 5 arranged at the paper entrance on the upper side of the figure, a drive roller 6 arranged at the paper exit on the lower side of the figure, a plurality of idler rollers 7 ... Are endlessly extended by a plurality of conveying rollers 8 ...

On the other hand, the driven belt 3 is looped endlessly by a plurality of idler rollers 9 including a roller closely adjoining the inlet roller 5 and the driving roller 6 of the driving belt 2 and a conveying roller 8. .

The rollers 5, 6, 7, ..., 8 ..., 9 ... of the driving and driven belts 2 and 3 are movable plates 10 arranged on both sides in the paper width direction as shown in FIGS. , 10
The belts 2 and 3 and the rollers 5, 6, 7 ..., 8 ...
Are configured to move integrally in the paper width direction.

Explaining this belt moving mechanism, as shown in FIG. 4, a pair of side plates 11, 11 are provided on both sides in the paper width direction inside the apparatus housing.
The drive shaft 12 and the guide shaft 13 are provided between the two side moving plates 1 and 11.
It is provided so as to pass through 0 and 10.

The drive shaft 12 is provided with male screws 12a and 12b in opposite halves on both sides of the axial center as a boundary.

On the other hand, female screw cylinders 14 and 14 are provided at the penetrating portions of the drive shafts 12 on both side moving plates 10 and 10, and a screw mechanism (ball screw mechanism is formed by the drive shaft 12 and the female screw cylinders 14 and 14). Is desirable) is configured.

The drive shaft 12 is rotationally driven by a belt moving motor (for example, a stepping motor) 15 shown in FIG. 4, and both moving plates 10 and 10 are simultaneously moved in opposite directions by a screw action by the rotation of the drive shaft 12. To do.

Thus, the driving and driven belts 2 and 3 on both sides of the paper in the paper width direction have the paper size (B5, A4,
A3 is shown), and the sheet can be moved in the paper width direction.

The guide shaft 13 serves as a guide when the moving plate moves. Further, in FIG. 4, 16 is a gear transmission mechanism that transmits the rotational force of the belt moving motor 15 to the drive shaft 12.

The entrance rollers 5 and 5 of the two-sided drive belt 2 are
Deflection of the paper P occurs in the recording section (both drive and driven belts 2, 3
2) to 5) are formed in a drum shape with a bulged central portion (hereinafter, the rollers 5 and 5 will be referred to as anti-deflection rollers), etc. The rollers 6, 7, ..., 8 ..., 9 ... are general cylindrical rollers.

Further, idler rollers (hereinafter, referred to as driven side inlet rollers) 9 and 9 at the inlet portions of the both side anti-deflection rollers 5 and 5 and the opposite side driven belts 3 and 3 opposed thereto.
Are provided on the common roller shafts 17 and 18 in a fixed state in the axial direction.

Both the driving side roller shaft 17 and the driven side roller shaft 17,
18 includes a plurality of intermediate guide rollers 19 ...
0 are provided in a zigzag arrangement in which the drive side and the driven side are axially displaced from each other at regular intervals in the axial direction, and the intermediate guide rollers 19 ... The sheet P is configured to come into contact with both the front and back surfaces.

Here, each intermediate guide roller 19 ..., 20
, Are supported so as to be movable in the axial direction with respect to the roller shafts 17, 18, and between the intermediate guide rollers 19, 20 ...
And intermediate guide rollers 19, 19, 20, 20 at both ends
, And compression coil springs 21 ... Are provided between the both side anti-bending rollers 5 and 5 and the driven side inlet rollers 9 and 9.

By means of the compression coil springs 21, the intermediate guide rollers 19, 20, 20 ... and the intermediate guide rollers 19, 19, 20, 20 at both ends and the anti-deflection rollers 5, 5 and the driven side inlet rollers 9, 9 are provided. Is maintained, the moving force is transmitted to the intermediate guide rollers 19 ..., 20 ... When the belt is moved, and the rollers 19 ...
20 moves in the axial direction together with the belts 2 and 3.

In the above structure, the paper P passing through the paper feed rollers 1 and 1 is introduced into the recording portion entrance while being bent in the direction of the drive belt 2 by the bending guide plate 4.

Here, the widthwise ends of the sheet P are corrected by pushing the outer edges (convex curved surfaces) of the drum-shaped anti-deflection rollers 5 and 5 across the drive belt 2 so that the sheet P becomes flat. In response to this, the bending-preventing action prevents the bending of the paper P at the paper delivery portion between the paper feed rollers 1 and 1 from entering the recording portion.

This anti-deflection action is clarified by experiments conducted by the inventor through trial and error, such as changing the roller shape and the belt cross-sectional shape, changing the difference between the sheet feeding speed and the belt conveying speed. It was done.

The principle of this anti-deflection action has not been clarified yet at this point, but (a) anti-deflection roller 5,
5 makes point contact between the drive belt 2 and both ends of the paper P in the width direction, and the contact state between them is assured and the contact pressure is increased. As a result, the paper P slides between the belts 2 and 3 and is bent. This is probably because the phenomenon of being carried in is eliminated, and (b) the convex curved surfaces of the anti-bending rollers 5 and 5 pull the sheet outward in the width direction, and the tension corrects the sheet in the flat direction.

Due to this anti-deflection action, the double-sided feed system and the flexible paper feed system are adopted, but the flexure of the paper P in the recording section is eliminated, and the paper P comes into contact with the nozzles of the recording heads B1 and B2 and the image flows. Alternatively, there is no possibility of causing a recording failure such as the occurrence of image white streaks due to nozzle clogging.

In addition, (i) a plurality of intermediate guide rollers 1
.., 20 ... sandwich the paper P between the belts on both sides in the paper width direction to give a conveying force, so that the paper P is corrected in the flat direction even in the intermediate portion. (Ii) Moreover, the intermediate guide Since the rollers 19, ..., 20 are arranged in a zigzag manner, the so-called waist is given to the paper P, so that the anti-flexing effect is further enhanced.

By the way, as the bending guide means, instead of the bending guide plate 4 of the above-described embodiment, a roller for bending the paper P may be provided near the paper moving line R.

Further, one or both of the drive-side and driven-side intermediate guide rollers 19, ..., 20 may be formed in a drum shape like the anti-deflection roller 5.

Further, contrary to the above embodiment, the sheet P may be bent toward the driven belt 3 side, and the driven belt side inlet roller 9 may be formed in a drum shape as an anti-deflection roller.

However, according to the experiment conducted by the inventor, the effect of preventing the bending is improved when the sheet P is bent toward the driving belt 2 and the driving belt side inlet roller 5 is formed in a drum shape as in the above embodiment. Became clear.

On the other hand, in the above embodiment, the drive and driven belts 2, 2, 3 on both sides in the paper width direction are selected according to the paper size.
Although 3 is moved in the opposite direction at the same time, only one belt may be moved.

[0060]

As described above, according to the present invention, a double-sided feed system in which both widthwise end portions of a recording sheet are sandwiched between the transport belts for transport, and the belt transport speed is lower than the paper feed speed. In an ink jet recording apparatus adopting a flexible paper feeding method in which the paper is intentionally flexed at the entrance portion of the recording unit, the flexure guide means regulates the flexure direction of the recording paper to a constant value and conveys the paper in the flexure direction. By forming the entrance roller of the belt into a drum shape with a bulging central portion as the anti-deflection roller, the recording sheet can be introduced into the recording section while being corrected in the flat direction.

As a result, it is possible to prevent the bending of the paper at the delivery portion from entering the recording portion, so that the bending of the paper in the recording portion is eliminated, the paper comes into contact with the nozzles of the recording head, and the image flows, or the nozzles There is no possibility of causing a recording failure such as clogging and image white streaks.

According to the second aspect of the present invention, in the structure in which one side of the front and back sides is the driving belt and the other side is the driven belt, the entrance roller of the driving belt is bent by using the deflection roller as the entrance roller of the driving belt. Compared with the case of using the stop roller, the effect of preventing the sheet from bending becomes more reliable.

On the other hand, according to the third aspect of the present invention, the interval between the conveyor belts on both sides in the paper width direction is changed according to the paper size, that is, a double-sided feeding method is adopted for each size paper and recording is performed. It is possible to obtain the effect of preventing the sheet from bending at the portion.

Further, according to the invention of claim 4, the plurality of intermediate guide rollers sandwich the sheet between the belts on both sides in the sheet width direction to give a conveying force, so that the sheet is flat in the intermediate portion. Since it is corrected, the anti-deflection effect becomes more reliable.

In this case, according to the sixth aspect of the invention, since the intermediate guide rollers are arranged in a zigzag manner, a so-called waist is given to the paper, whereby the anti-deflection effect is enhanced.

Further, according to the invention of claim 5, in the structure of claim 3 in which the distance between the two side conveyor belts can be changed according to the paper size, the moving force of the movable conveyor belt is transmitted to each intermediate guide roller via the coil spring. Then, the guide roller automatically moves together with the movable conveyance belt. That is, the intermediate guide roller does not hinder the movement of the belt,
The anti-bending assisting action of the guide roller is fulfilled without any problem for each paper size.

[Brief description of drawings]

FIG. 1 is a schematic front view of a recording unit of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a partially enlarged perspective view of a paper transport mechanism of a recording unit.

FIG. 4 is a plan view of the same.

FIG. 5 is a diagram showing a part of FIG. 4 in an enlarged manner.

[Description of Reference Signs] 1, 1 Registration roller A Paper transport mechanism (paper transport means) 2 Drive belt (movable transport belt) 3 Follower belt (movable transport belt) 4 Bending guide plate (bending guide means) 5 Drive belt side inlet roller (Anti-deflection roller) 9 Driven belt side inlet roller (idler roller) 10, 10 Moving plate constituting belt moving means 12 Same drive shaft 15 Same belt moving motor 17 Roller shaft of drive belt side inlet roller 18 Driven belt side inlet roller Roller shaft 19 ... Drive belt side intermediate guide roller 20 ... Driven belt side intermediate guide roller 21 ... Coil spring

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location B65H 5/38 (72) Inventor Koichi Baba 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Engineering Co., Ltd. Incorporated (72) Inventor, Yoshiko Kawauchi 1-22-29, Tamazo, Chuo-ku, Osaka Mita Engineering Co., Ltd. (72) Inventor, Seto Hori 1-2-28, Tamatsukuri, Chuo-ku, Osaka Mita Engineering Co., Ltd. Within

Claims (6)

[Claims] 1. A recording unit provided with a belt conveying unit and a recording head, wherein a recording sheet sent to a recording unit by a sheet feeding roller is conveyed by the belt conveying unit while the recording head is moved to the recording sheet. In an ink jet recording apparatus for recording an image by ejecting ink from nozzles, as the belt conveying means, the paper feed is performed on both sides in the paper width direction with both widthwise end portions of the recording paper sandwiched from the front and back sides. A pair of front and back conveyance belts that convey at a lower speed than the rollers, and a plurality of rollers around which the conveyance belts are wound, including an entrance roller arranged at the paper entrance, are provided. A bending guide means for restricting the bending direction of the recording paper to a constant value is provided between the paper feeding roller and the bending guide hand of the front and back conveyance belts. An ink jet recording apparatus characterized in that the entrance roller of the conveyor belt in the sheet bending direction due to the step is formed in a drum shape having a bulged central portion as a bending prevention roller. 2. The ink jet recording apparatus according to claim 1, wherein one of the two conveyor belts is a drive belt driven by a motor, and the other is a driven belt that is in contact with the drive belt and transmits a rotational force. Configure and
An ink jet recording apparatus, characterized in that the bending guide means is configured to bend a sheet toward a drive belt side, and an entrance roller of the drive belt is a bending prevention roller. 3. The inkjet recording apparatus according to claim 1, wherein at least one of the conveyor belts on both sides in the paper width direction is supported as a movable conveyor belt so as to be movable in the paper width direction. An inkjet recording apparatus comprising: a belt moving unit that moves a conveyor belt along with a roller in a sheet width direction according to a sheet size. 4. The ink jet recording apparatus according to claim 1, wherein entrance rollers of the conveyor belt on both sides in the paper width direction are provided on a common roller shaft, and recording is performed on both entrance rollers on the roller shaft. An ink jet recording apparatus comprising a plurality of intermediate guide rollers that rotate while being in contact with a sheet at intervals in the axial direction. 5. The ink jet recording apparatus according to claim 3, wherein each of the intermediate guide rollers according to claim 4 is provided so as to be movable in the paper width direction, and the intermediate guide rollers are provided between these intermediate guide rollers and at both ends. An ink jet recording apparatus characterized in that a coil spring is provided between the roller and the roller to push the rollers in a direction in which they are separated from each other. 6. The ink jet recording apparatus according to claim 4 or 5, wherein the respective intermediate guide rollers that contact the front and back side of the recording sheet and the intermediate guide rollers that contact the opposite side are displaced from each other in the sheet width direction. An ink jet recording apparatus, which is provided in a staggered arrangement.