JP3267801B2 - Ink jet recording device - Google Patents

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 for an output device of a computer or the like.

[0002]

2. Description of the Related Art In an ink jet recording apparatus, a recording section includes:
The apparatus includes a recording head provided with a number of nozzles (ink ejection ports), and is configured to eject an ink from the nozzles to a recording sheet conveyed by a sheet conveying unit to record an image.

Conventionally, as a paper conveying means in this ink jet recording apparatus, generally, Japanese Patent Application Laid-Open No. 5-1856 has been disclosed.
No. 61 and Japanese Patent Application Laid-Open No. 5-330037 both use a belt.

Further, as a belt conveyance system suitable for adopting a double-sided recording system (a system for 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 system in which the paper is conveyed by the above.

According to this method, almost all areas of both sides of the sheet are 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 size of the recording unit can be reduced as compared with the case where the recording heads on both the front and back sides are displaced in the sheet conveyance direction.

[0006]

However, in this case,
The following problems arise.

A paper feed roller is provided at the entrance side of the recording unit as means for feeding the paper to the recording unit. However, it is technically difficult to completely synchronize the paper feeding roller with the transport belt of the recording unit. 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 transport trouble will occur due to synchronization failure.

Therefore, it is considered to be a good idea to intentionally provide a speed difference between the sheet feeding roller and the conveyor belt and to design the conveyance structure based on the speed difference.

However, in this case, the paper transport speed of the paper feed roller (hereinafter, referred to as the paper feed speed) is set to be lower than the paper transport speed of the transport belt (hereinafter, referred to as the belt transport speed), and the brake is performed by the paper feed roller. When the sheet is drawn into the conveyance belt while applying the pressure, the sheet conveyance speed increases at the moment when the sheet comes off the sheet feeding roller, and the image is disturbed.

Therefore, conversely, the paper feeding speed is set to be higher than the belt conveyance speed, and the paper is delivered while being bent between the paper feeding roller and the conveyance belt (hereinafter, the flexible paper feeding system). It is more desirable to take.

However, in this case, depending on the speed difference, the paper may be pushed between the transport belts in a warped state.

In this case, since the gap between the recording heads disposed opposite to each other is very small (about 2 mm), the paper comes into contact with the nozzles of the recording head to cause an image to flow, or the nozzles are clogged, resulting in image white stripes. Causes recording failure such as occurrence of

In view of the above, the present invention is directed to a recording unit (conveying belt) in which a sheet is flexed at a sheet transfer portion between a sheet feeding roller and a recording unit while a both-end feeding system and a flexible sheet feeding system are employed. The present invention provides an ink jet recording apparatus that can prevent the ink jet recording apparatus from being taken in during the period.

[0014]

According to a first aspect of the present invention, there is provided a recording unit provided with a belt conveying unit and a recording head.
The recording paper sent to the recording unit by the paper feed roller
In an ink jet recording apparatus for recording an image by discharging ink from nozzles of a recording head on the same sheet while transporting the same by the belt transporting means, the belt transporting means includes, on both sides in the paper width direction, the width of the recording paper. A pair of front and back conveyance belts that convey at a lower speed than the paper feed roller in a state where both ends in the direction are sandwiched from the front and back sides,
And a plurality of rollers including inlet rollers arranged in the paper inlet Both conveyor belt is passed over provided between the paper inlet and the paper feed roller of the belt conveyor unit, the paper
Deflection of record sheet based on the speed difference between the paper roller and a double conveyor belt
With the Minokata toward providing a deflection guide means for regulating a constant, on both surfaces both conveyor belts, the entrance roller of the conveyor belt in a direction bending the sheet by the bending guide means, bulging central portion as a stop roller deflection drum Formed into a shape
Center the outer peripheral surface of this entrance roller
It is configured to be in contact with recording paper .

According to a second aspect of the present invention, in the configuration of the first aspect, one of the two conveyor belts is a drive belt driven by a motor, and the other is a driven belt which is brought into contact with the drive belt to transmit torque. The bending guide means is configured to bend the sheet toward the drive belt, and the entrance roller of the drive belt is a deflection preventing roller.

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

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

According to a fifth aspect of the present invention, in the configuration of the third aspect, each of the intermediate guide rollers according to the fourth aspect is provided so as to be movable in the sheet width direction, and the intermediate guide rollers are provided between the intermediate guide rollers and at both ends. A coil spring that presses each of these rollers in a direction away from each other is provided between the roller and the inlet roller.

According to a sixth aspect of the present invention, in the configuration of the fourth or fifth aspect, each of the intermediate guide rollers contacting the front and back sides of the recording sheet and each of the intermediate guide rollers contacting the opposite side are arranged in the sheet width direction. It is provided in a staggered arrangement with displacement.

[0020]

According to the above construction, the recording paper is transferred between the paper feed roller and the recording section (conveying belt) by the both-end feeding method and the flexible paper feeding method, and the paper is bent by the bending guide means at this transfer portion. The direction is regulated to be constant.

At the entrance of the recording section, the correcting force in the direction in which the recording paper is flattened by pressing both ends in the width direction of the recording paper against the outer peripheral surface (convex curved surface) of the drum-shaped deflection preventing roller across the conveyor belt. In response to this, the bending of the sheet at the transfer portion is prevented from entering the recording portion by the bending preventing action. This has been clarified by the inventors' experiments.

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

On the other hand, according to the configuration of the third aspect, the interval between the conveying belts on both sides in the sheet width direction is changed according to the sheet size, that is, both ends are fed for each size sheet and recording is performed. It is possible to obtain the effect of preventing the sheet from bending at the portion.

Further, according to the fourth aspect of the present invention, the plurality of intermediate guide rollers sandwich the sheet between the belts on both sides in the sheet width direction and apply a conveying force, so that the sheet is flat even in the intermediate portion. Since the correction is performed, the bending prevention effect is further ensured.

In this case, according to the structure of the sixth aspect, since the intermediate guide rollers are arranged in a staggered manner, a so-called stiffness is given to the sheet, whereby the effect of preventing bending is enhanced.

According to a fifth aspect of the present invention, in the third aspect of the present invention, the distance between the two conveyor belts can be changed according to the sheet size, and the moving force of the movable conveyor belt is transmitted to each intermediate guide roller via a coil spring. The guide roller automatically moves together with the movable conveyor belt.

[0027]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

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

This recording unit transports recording paper (hereinafter simply referred to as paper) P sent from a paper feed unit (not shown) via the registration rollers 1 and 1 on a paper moving line R from the upper side to the lower side in the figure. The transport mechanism A and front and back recording heads B1 and B2 provided on both sides of the paper moving line R for double-sided recording (here, for color recording, both recording heads B1 and B2 are connected to the paper moving line R). And a drying device C for drying by blowing hot air from a heater and a fan on the recorded paper P.

The paper transport mechanism A has both driving and driven belts 2 and 3 disposed on both sides of the paper 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. The two belts 2 and 3 are simultaneously rotated by being transmitted at a contact portion.

The driving and driven belts 2 and 3 are
As shown in FIGS. 3 and 4, the sheet P is arranged on both sides in the sheet width direction, and both ends in the width direction of the sheet P are sandwiched between the belts 2 and 3 and are conveyed by a both-ends feeding method.

Here, the belt conveying speed is set lower than the sheet feeding speed, and the sheet P is fed to the recording section (between both belts 2 and 3) while being bent as shown in FIG.

A slightly curved plate-like flexible guide plate 4 is provided between the registration rollers 1 and 1 and the recording section.

The flexure guide plate 4 is provided from the driven belt 3 side to the drive belt 2 side. The guide plate 4 pushes the paper P toward the drive belt 2, and the direction of flexure is in the direction of the drive belt 2. Be regulated.

The drive belt 2 includes an inlet roller 5 disposed at the upper paper inlet, a drive roller 6 disposed at the lower paper outlet, a plurality of idler rollers 7,... Are endlessly wrapped by a plurality of transport rollers 8 provided in each of the plurality of rollers.

On the other hand, the driven belt 3 is endlessly wrapped around a plurality of idler rollers 9 including a roller which is close to and opposed to the entrance roller 5 and the driving roller 6 of the driving belt 2 and the conveying rollers 8. .

Each of the rollers 5, 6, 7,..., 8,..., 9 of the driving and driven belts 2, 3 is provided with a moving plate 10 arranged on both sides in the sheet width direction as shown in FIG. , 10
The belts 2, 3 and the rollers 5, 6, 7,..., 8,.
Are configured to move integrally in the sheet width direction.

The belt moving mechanism will be described. As shown in FIG. 4, a pair of side plates 11, 11 are provided on both sides in the paper width direction in the apparatus housing.
The drive shaft 12 and the guide shaft 13 are moved between
It is provided so as to penetrate 0 and 10.

The drive shaft 12 is provided with external threads 12a and 12b in opposite halves on both sides with respect to the axial center.

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

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

In this manner, both the driving and driven belts 2 and 3 on both sides in the sheet width direction have the sheet size (B5, A4,
A3) (see A3).

The guide shaft 13 performs a guiding action when the movable plate moves. In FIG. 4, reference numeral 16 denotes a gear transmission mechanism for transmitting the rotational force of the belt moving motor 15 to the drive shaft 12.

The entrance rollers 5, 5 of the both-side drive belt 2 are
The deflection of the paper P is caused in the recording unit (both driving and driven belts 2 and 3).
As shown in FIG. 2 to FIG. 5, as a deflection-preventing roller for preventing the roller from entering, the central portion is formed in a drum shape with a bulging center (hereinafter, the rollers 5 and 5 are referred to as deflection-preventing rollers). , 8,..., 9... Are general cylindrical rollers.

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

The drive-side and driven-side roller shafts 17,
18 have a plurality of intermediate guide rollers 19.
.. Are provided at regular intervals in the axial direction and in a staggered arrangement in which the drive side and the driven side are displaced in the axial direction. These intermediate guide rollers 19,. It is configured to contact both sides of the sheet P to be printed.

Here, each intermediate guide roller 19,.
… Are supported movably in the axial direction with respect to the roller shafts 17, 18, and between these intermediate guide rollers 19, 20,
And intermediate guide rollers 19, 19, 20, 20 at both ends.
The compression coil springs 21 are provided between the first and second side deflection preventing rollers 5 and 5 and the driven side entrance rollers 9 and 9.

By the compression coil springs 21, the intermediate guide rollers 19, 20,..., The intermediate guide rollers 19, 19, 20, 20 at both ends, the deflection preventing rollers 5, 5, and the driven side entrance rollers 9, 9 Are maintained, and at the time of the belt movement described above, the moving force is transmitted to each of the intermediate guide rollers 19,.
20 move in the axial direction together with the belts 2 and 3.

In the above configuration, the sheet P that has passed through the sheet feeding rollers 1 and 1 is introduced into the entrance of the recording unit while being bent in the direction of the drive belt 2 by the bending guide plate 4.

Here, the paper P is flattened by pressing both ends in the width direction against the outer peripheral surfaces (convex curved surfaces) of the drum-shaped deflection preventing rollers 5, 5 across the drive belt 2. In response to this, the bending of the sheet P at the sheet transfer portion between the sheet feeding rollers 1 and 1 is prevented from entering the recording unit.

This bending prevention effect is apparent from experiments repeatedly performed by the inventor through trial and error, such as changing the roller shape and the belt cross-sectional shape, and changing the difference between the sheet feeding speed and the belt conveying speed. It was done.

Although the principle of the bending preventing action has not been elucidated yet at this time, (a) the bending preventing rollers 5 and 5
5, the drive belt 2 makes point contact with both ends in the width direction of the sheet P, so that these contact states are ensured and the contact pressure is increased. As a result, the sheet P slides between the belts 2 and 3 to bend. It is considered that the phenomenon of bringing in the paper is eliminated and (b) the paper is pulled outward in the width direction by the convex curved surfaces of the deflection preventing rollers 5 and 5, and the paper is corrected in the flat direction by the tension.

Due to this bending preventing action, the sheet P does not bend in the recording portion while the both-end feeding method and the bending sheet feeding method are used, and the sheet P comes into contact with the nozzles of the recording heads B1 and B2 and an image flows. Alternatively, there is no danger of causing a recording failure such as clogging of the nozzle and generation of white stripes in the image.

In addition, (i) a plurality of intermediate guide rollers 1
9 and 20 ... sandwich the sheet P between the belts on both sides in the sheet width direction to impart a conveying force, so that the sheet P is corrected in the flat direction even in the middle part. Since the rollers 19..., 20 are arranged in a staggered manner, the sheet P is given a so-called stiffness, so that the bending prevention effect is further enhanced.

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

One or both of the drive-side and driven-side intermediate guide rollers 19, 20... May be formed in a drum shape similar to the deflection preventing roller 5.

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

However, according to the experiment by the inventor, the effect of preventing the deflection is higher when the sheet P is bent toward the drive belt 2 and the drive belt side entrance roller 5 is formed in a drum shape as in the above embodiment. Became clear.

On the other hand, in the above embodiment, the driving and driven belts 2, 2, 3,
3 is simultaneously moved in the opposite direction, but a structure may be adopted in which only one belt is moved.

[0060]

As described above, according to the present invention, a double-end feed system is used in which both ends of the recording sheet in the width direction are sandwiched between the conveyor belts and the conveyor is conveyed, and the belt conveying speed is lower than the paper feeding speed. In the ink jet recording apparatus which adopts a flexible sheet feeding method in which the sheet is intentionally bent at the entrance portion of the recording section by setting the direction, the bending direction of the recording sheet is regulated to be constant by the bending guide means, and the conveyance in the sheet bending direction is performed. By forming the entrance roller of the belt as a deflection-preventing roller in the shape of a drum with a bulging central portion, the recording paper can be introduced into the recording section while correcting it in the flat direction.

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

According to the second aspect of the present invention, in a configuration in which one side of the front and back sides is a drive belt and the other side is a driven belt, the entrance roller of the drive belt is a deflection preventing roller, so that the entrance roller of the driven belt is bent. As compared with the case of using a stop roller, the effect of preventing the sheet from bending is more reliable.

On the other hand, according to the third aspect of the present invention, the distance between the conveying belts on both sides in the sheet width direction is changed according to the sheet size, that is, both ends are fed for each size sheet and recording is performed. It is possible to obtain the effect of preventing the sheet from bending at the portion.

Further, according to the fourth aspect of the present invention, the plurality of intermediate guide rollers sandwich the sheet between the belts on both sides in the sheet width direction to apply a conveying force, so that the sheet is flat even in the intermediate portion. Since the correction is performed, the bending prevention effect is further ensured.

In this case, according to the invention of claim 6, since the intermediate guide rollers are arranged in a staggered manner, a so-called stiffness is given to the sheet, thereby enhancing the bending preventing effect.

According to the fifth aspect of the present invention, in the configuration of the third aspect, the interval between the two-sided conveying belts can be changed according to the sheet size, the moving force of the movable conveying belt is transmitted to each intermediate guide roller via a coil spring. The guide roller automatically moves together with the movable conveyor belt. That is, the intermediate guide roller does not hinder the movement of the belt,
The bending roller assists the guide roller to perform its function without difficulty for each paper size.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a recording unit of an ink jet 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 sheet transport mechanism of a recording unit.

FIG. 4 is a plan view of the same.

FIG. 5 is an enlarged view showing a part of FIG. 4;

[Explanation of symbols]

 Reference Signs List 1, 1 registration roller A paper transport mechanism (paper transport means) 2 drive belt (movable transport belt) 3 driven belt (movable transport belt) 4 flexible guide plate (flexible guide means) 5 drive belt side entrance roller (flexure prevention roller) 9 Driven belt side entrance roller (idler roller) 10,10 Moving plate constituting belt moving means 12 Same drive shaft 15 Same belt movement motor 17 Roller shaft of drive belt side entrance roller 18 Roller shaft of driven belt side entrance roller 19 ... Drive belt side intermediate guide roller 20: driven belt side intermediate guide roller 21: coil spring

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Baba 1-2-2, Tamazuki, Chuo-ku, Osaka-shi Inside Mita Kogyo Co., Ltd. (72) Inventor Yoshiko Kawachi 1-2-28, Tamazuki, Chuo-ku, Osaka-shi Mita Kogyo Inside (72) Inventor Setsuo Hori 1-2-2, Tamazo, Chuo-ku, Osaka-shi Mita Kogyo Co., Ltd. (56) References JP-A-3-8641 (JP, A) JP-A-5-112000 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 13/00-13/32

Claims (6)

(57) [Claims] A recording section provided with a belt conveying means and a recording head, wherein the recording sheet fed to the recording section by a paper feed roller is conveyed by the belt conveying means while the recording head is moved to the recording sheet. In the ink jet recording apparatus that records an image by discharging ink from nozzles, the belt conveyance means is configured such that the paper feed roller sandwiches both ends in the width direction of the recording sheet from both sides in the sheet width direction. A pair of front and back conveyor belts for conveying at a low speed, and a plurality of rollers around which both conveyor belts are wound including an entrance roller disposed at a sheet entrance are provided. Speed difference between the feed roller and both conveyor belts
Provided with a deflection guide means for regulating a constant Deflection Minokata direction of record sheet based on, on both surfaces both conveyor belts,
The inlet roller of the paper deflection direction transport belt by the deflection guide means, formed on the stopper barrel shape bulged central portion as the roller deflection, the central portion outer peripheral surface of the inlet roller
It is configured to make contact with the recording paper through the conveyor belt
An ink jet recording apparatus characterized by the. 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 which is in contact with the drive belt and transmits a rotational force. Make up,
An ink jet recording apparatus, wherein the bending guide means is configured to bend the sheet toward the driving belt, and the entrance roller of the driving belt is a deflection preventing roller. 3. The ink jet recording apparatus according to claim 1, wherein 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. An ink jet recording apparatus comprising a belt moving means for moving a conveying belt in a sheet width direction together with a roller according to a sheet size. 4. The ink jet recording apparatus according to claim 1, wherein an entrance roller of the transport belt on both sides in the sheet width direction is provided on a common roller shaft, and recording is performed between the entrance rollers on both sides of the roller shaft. An ink jet recording apparatus comprising a plurality of intermediate guide rollers which rotate while being in contact with a sheet and are provided at intervals in an 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 sheet width direction, and between the intermediate guide rollers, and the intermediate guide rollers at both ends and the entrance. An ink jet recording apparatus, comprising: a coil spring that presses each of these rollers in a direction away from each other. 6. The ink jet recording apparatus according to claim 4, wherein each of the intermediate guide rollers contacting the front and back sides of the recording paper and each of the intermediate guide rollers contacting the opposite side are displaced from each other in the paper width direction. An ink jet recording apparatus provided in a staggered arrangement.