JP2002179319A - Paper feed mechanism for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pucker in a recording paper sheet. SOLUTION: A paper feed mechanism for an image forming device comprises feed rollers and a plurality of star wheels for pressing recording the paper sheet against the feed rollers. The star wheels have center shafts crossing a center shaft of the feed rollers in given directions, so as to assist a feed as stretching the recording paper sheet toward both edges thereof parallel to the feed direction thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper transport mechanism of an image forming apparatus, and more particularly, to a paper transport mechanism of an ink jet printer or the like.

[0002]

2. Description of the Related Art As a paper transport mechanism of a conventional image forming apparatus, there is known a paper transport mechanism in which a recording sheet is nipped and driven by a driving rubber roller and a driven rubber roller for pressing the recording sheet against the driving rubber roller. I have.

However, in an image forming apparatus using ink for printing or an image forming apparatus having a portion through which unfixed ink passes in a conveyance path, a rubber roller and a conveyance path are contaminated with ink during conveyance of a recording sheet. As a result, the recording surface of the recording paper is soiled. For this reason, the conveyance method of nipping the recording paper between the driving rubber roller and the driven rubber roller is not suitable for an image forming apparatus using ink.

Therefore, as a paper transport mechanism suitable for an image forming apparatus using ink, a star wheel which is in point contact with a recording surface is employed instead of a driven rubber roller, and the star wheel is used in a paper feeding direction. Parallel to
In addition, a paper transport mechanism arranged perpendicular to the recording surface is known (for example, see Japanese Patent Application Laid-Open No. 5-42732).

[0005]

A paper transport mechanism employing a conventional star wheel can prevent contamination of rollers,
When transporting recording paper that has been wrinkled by absorbing ink,
In some cases, the wrinkled portion rubs against members around the transport path and contaminates those members with ink. When the members around the conveyance path are contaminated, the recording paper is eventually contaminated by the contamination of the members.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a paper transport mechanism of an image forming apparatus capable of preventing recording paper from being stained by stretching the paper during transportation. .

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided a transport roller, and a recording paper is pressed against the transport roller to cooperate with the transport roller to transport the recording paper. With a plurality of star wheels forming a row,
Each of the star wheels has a central axis intersecting the central axis of the transport roller at a predetermined angle so that the recording paper is transported while being stretched on both sides in a direction perpendicular to the paper feeding direction. A transport mechanism is provided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a conveying roller is rotated by a driving force inputted from a central axis to make line contact with a sheet, and a star wheel is pressed against the conveying roller by point contact. It is driven and rotated with respect to the transport roller.

In the present invention, the predetermined angle may be an angle formed by the center axis of the star wheel and the center axis of the transport roller when viewed from the recording surface of the recording paper. Further, the predetermined angle may be an angle formed by the center axis of the star wheel and the center axis of the transport roller when viewed from the sheet feeding direction.

With this configuration, the recording paper is conveyed while being stretched to both sides in a direction perpendicular to the paper feeding direction, and even when the recording paper absorbs ink and swells, wrinkles are generated. Is prevented. Therefore, the periphery of the transport path is not contaminated with ink, and the recording paper can be prevented from being stained.

Further, in the paper transport mechanism of the image forming apparatus according to the present invention, the crossing angle between the central axis of the plurality of star wheels and the central axis of the transport roller may be larger as the distance to the both ends of the row increases. Further, the plurality of star wheels may be smaller as the distance between them is closer to both ends of the row. Further, as for the plurality of star wheels, the closer to both ends of the row, the higher the pressure for pressing the recording paper may be.

With such a configuration, the force for stretching the recording paper in the direction perpendicular to the paper feeding direction increases as the distance from both ends of the star wheel array increases. Therefore, wrinkles of the swollen recording paper can be effectively prevented without imposing an excessive load on the recording paper.

Further, in the paper transport mechanism of the image forming apparatus according to the present invention, the plurality of star wheels may be arranged so as to be shifted to the downstream side in the paper supply direction as the closer to both ends of the row. With this configuration, when the recording paper P is transported, wrinkling of the recording paper can be prevented in a wide range from the upstream side to the downstream side in the paper feeding direction.

The present invention is particularly effective in an image forming apparatus such as an ink-jet printer, which can easily wrinkle recording paper.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. The present invention is not limited by the embodiment.

Embodiment 1 A paper transport mechanism of an ink jet printer according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory view showing a schematic configuration of a paper transport mechanism according to a first embodiment of the present invention, FIG. 2 is a perspective view schematically showing characteristic portions of the paper transport mechanism according to the first embodiment of the present invention, FIG. 4 is a plan view of the characteristic portion shown in FIG. 2, and FIG. 4 is a front view of the characteristic portion shown in FIG.

First, the relationship between the process of transporting the recording paper P by the paper transport mechanism 1 and the printing process by the printing unit 5 will be schematically described with reference to FIG. The recording paper P is stored in a paper feed tray 2 provided in the paper transport mechanism 1, and when a printing request based on image information from a computer or the like (not shown) is made, the recording paper P is fed one by one by a pickup roller 3. The sheet is conveyed to the paper roller 4.

The recording paper P transported by the pickup roller 3 passes through a paper transport path (not shown) by the paper feed roller 4 and reaches the printing unit 5. The printing unit 5 is composed of an ink carriage 7 on which an ink head 6 is mounted, and an ink carriage holding shaft 8 arranged to facilitate the scanning of the ink head. The ink is ejected and printed on the recording paper P.

At this time, the recording paper P is temporarily stopped, and when the ink carriage 7 completes scanning of one line (one direction), the recording paper P corresponding to a plurality of ink nozzles of the ink head 6 is conveyed. Is made. As described above, in the printing unit 5, the image information is written on the recording paper P by continuously performing the above-described processing corresponding to the image information. The printed recording paper P is conveyed along the conveyance path 11 by the star wheel 9 and the conveyance rollers 10, discharged to the paper discharge tray 12, and provided to the user as a printed matter.

Next, structural features of the paper transport mechanism according to the first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 2 to 4, the paper transport mechanism 1 according to the first embodiment of the present invention presses the recording paper P against the transport roller 10 and cooperates with the transport roller 10 to perform recording. A plurality of star wheels 9 that form a row in a direction F2 substantially orthogonal to the paper feeding direction F1 for transporting the paper P;
The central axis 13 of the transport roller 10 so that the transport is performed while being stretched to both sides in a direction F2 orthogonal to
4 at a predetermined angle.

More specifically, as shown in FIGS. 2 to 4, the star wheel 9 has a central shaft 13 so that a convex tip 9 a provided on the outer periphery of the star wheel 9 is substantially in contact with the center of the discharge roller 10. It is provided as an axis. The center axis 13
Consists of a coil spring.

In particular, as shown in FIG. 3, when the star wheel 9 is viewed from the recording surface of the recording paper P, the central axis 13 of the star wheel 9 and the central axis 14 of the transport roller 10 form a predetermined angle. It is provided so as to make it easier. That is, the star wheel 9 is provided so as to spread in a C-shape toward the downstream side in the paper feeding direction F1.

As a result, the recording paper P is conveyed while being stretched to both sides in the direction F2 perpendicular to the paper feeding direction F1, and even when the recording paper P absorbs ink and swells, wrinkling is prevented. Is done. Therefore, the periphery of the transport path 11 (see FIG. 1) is not contaminated with ink, and the recording paper P is prevented from being contaminated.

The center shaft 1 made of a coil spring
3 is supported by a housing (not shown) by a support portion (not shown), so that the tip 9a of the convex portion of the star wheel 9 presses the recording paper P against the transport roller 10. Therefore, when the transport roller 10 rotates, the central shaft 13 also rotates following the transport roller 10 to transport and discharge the recording paper P.

Second Embodiment Next, a paper transport mechanism according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a plan view showing a characteristic portion of the paper transport mechanism according to the second embodiment of the present invention, and FIG. 6 is a front view of the characteristic portion shown in FIG. The members having the same names as those used in the first embodiment will be described using the same reference numerals.

As shown in FIGS. 5 and 6, and particularly in FIG. 6, the paper transport mechanism 21 according to the second embodiment includes a central shaft 13 of the star wheel 9 when each star wheel 9 is viewed from the paper feeding direction F1. And the central axis 14 of the transport roller 10 are provided at predetermined angles. Other configurations are the same as those in the first embodiment.

Even when the star wheel 9 is provided in this manner, the recording paper P is fed in the paper feeding direction F, as in the first embodiment.
It is conveyed while being stretched to both sides in the direction F2 orthogonal to 1. Therefore, even when the recording paper P absorbs ink and swells, generation of wrinkles is prevented.
The periphery of the transport path 11 (see FIG. 1) is not contaminated with ink, and the recording paper P is prevented from being contaminated.

Third Embodiment Next, a paper transport mechanism according to a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a plan view showing a characteristic portion of the sheet transport mechanism according to Embodiment 3 of the present invention.
Note that members having the same names as those used in the above-described first and second embodiments will be described using the same reference numerals.

As shown in FIG. 7, in the paper transport mechanism 31 according to the third embodiment, the closer the ends of the row to the both ends of the row, the more the center wheel 13 and the transport roller 10
Are provided so that the angle of intersection with the central axis 14 becomes large. Other configurations are the same as those in the first embodiment.

When a plurality of star wheels 9 are provided in this manner, the recording paper P is fed closer to both ends of the row in the paper feeding direction F1.
The force of stretching in the direction F2 perpendicular to the direction becomes stronger. Therefore, wrinkles of the swollen recording paper P can be efficiently prevented without imposing an excessive load on the recording paper P.

Fourth Embodiment Next, a paper transport mechanism according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a plan view showing a characteristic portion of a sheet transport mechanism according to Embodiment 4 of the present invention.
The members having the same names as those used in the first to third embodiments are described using the same reference numerals.

As shown in FIG. 8, in the paper transport mechanism 41 according to the fourth embodiment, the plurality of star wheels 9 are provided such that the closer the distance between them is to the both ends of the row, the smaller the distance. Other configurations are the same as those in the first embodiment.

When a plurality of star wheels 9 are provided in this manner, the force for stretching the recording paper P in the direction F2 perpendicular to the paper feeding direction F1 becomes stronger as it approaches both ends of the row of the star wheels 9. Therefore, similarly to the above-described third embodiment, wrinkles of the swollen recording paper P can be efficiently prevented without imposing an excessive load on the recording paper P.

Embodiment 5 Next, a paper transport mechanism according to Embodiment 5 of the present invention will be described with reference to FIG. FIG. 9 is a plan view showing a characteristic portion of a sheet transport mechanism according to Embodiment 5 of the present invention.
The members having the same names as those used in the first to fourth embodiments will be described using the same reference numerals.

As shown in FIG. 9, the paper transport mechanism 51 according to the fifth embodiment is provided such that a plurality of star wheels 9 are shifted farther downstream in the paper feeding direction F1 as they are closer to both ends of the row. Have been. That is, the plurality of star wheels 9 are provided in a stepped manner. Other configurations are the same as those of the first embodiment.

When the plurality of star wheels 9 are provided in this manner, wrinkles of the recording paper P can be prevented over a wide range from upstream to downstream in the paper feeding direction F1 when the recording paper P is transported. Become.

[0037]

According to the present invention, each star wheel has:
The central axis is provided so as to intersect the central axis of the transport roller at a predetermined angle so that the recording paper is transported while being stretched to both sides in the direction perpendicular to the paper feeding direction. As a result, it is possible to prevent the recording paper from being stained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a schematic configuration of a paper transport mechanism according to a first embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a characteristic portion of the paper transport mechanism according to the first embodiment of the present invention.

FIG. 3 is a plan view of a characteristic portion shown in FIG. 2;

FIG. 4 is a front view of a characteristic portion shown in FIG. 2;

FIG. 5 is a plan view illustrating a characteristic portion of a sheet transport mechanism according to a second embodiment of the present invention.

FIG. 6 is a front view of a characteristic portion shown in FIG. 5;

FIG. 7 is a plan view illustrating a characteristic portion of a sheet transport mechanism according to a third embodiment of the present invention.

FIG. 8 is a plan view illustrating a characteristic portion of a sheet transport mechanism according to a fourth embodiment of the present invention.

FIG. 9 is a plan view showing a characteristic portion of a sheet transport mechanism according to Embodiment 5 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Paper conveyance mechanism 9 ... Star wheel 9a ... Convex tip 10 ... Conveyance rollers 13, 14 ... Center axis

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Uehara 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Yoichi Takezawa 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Keiichi Fukuyama 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Kiyoshi Takato 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation F term (reference) 2C059 BB07 BB21 CC15 3F049 AA01 CA02 LA07 LB03 3F053 HA01 HB03 LA07 LB03

Claims (7)

[Claims] 1. A conveying roller and a plurality of star wheels for forming a row in a direction substantially perpendicular to a sheet feeding direction for pressing a recording sheet against the conveying roller and cooperating with the conveying roller to convey the recording sheet. Each star wheel has an image whose central axis intersects the central axis of the transport roller at a predetermined angle so that the recording paper is transported while being stretched to both sides in a direction perpendicular to the paper feeding direction. Paper transport mechanism of the forming device. 2. The paper transport mechanism according to claim 1, wherein the predetermined angle is an angle formed by a central axis of the star wheel and a central axis of the transport roller when viewed from a recording surface of the recording paper. 3. The paper transport mechanism of the image forming apparatus according to claim 1, wherein the predetermined angle is an angle formed by a central axis of the star wheel and a central axis of the transport roller when viewed from the paper feed direction. 4. The image forming apparatus according to claim 1, wherein the closer the ends of the plurality of star wheels are to both ends of the row, the larger the intersection angle between the center axis of the star wheels and the center axis of the conveying roller is. Paper transport mechanism. 5. The paper transport mechanism of an image forming apparatus according to claim 1, wherein the distance between the plurality of star wheels is smaller as the distance between the star wheels is closer to both ends of the row. 6. The sheet conveyance of the image forming apparatus according to claim 1, wherein the plurality of star wheels are arranged so as to be shifted to the downstream side in the sheet feeding direction as being closer to both ends of the row. mechanism. 7. The paper transport mechanism of an image forming apparatus according to claim 1, wherein a pressure of the plurality of star wheels closer to both ends of the row is higher than a pressure of the recording paper.