JP2002211056A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of effectively preventing staining of the apparatus and adhering of ink to a rear face of a sheet even when margin-less printing is executed. SOLUTION: After a sheet S is conveyed to a lower portion of image forming means 1, 2 by sheet conveying means 4, 5, ink is ejected to the sheet S by moving the image forming means 1, 2 in a direction perpendicular to a sheet conveyance direction to form an image on the sheet S. At that time, the conveyed sheet S is supported from the lower side by a plurality of spurs 9 provided to the lower portion of the image forming means 1, 2. The ink which is ejected from the image forming means 1, 2 and is got adhered to the sheet S is sucked by an ink sucking means 10 provided to a lower portion of the plurality of spurs 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having an image forming means of an ink jet system, wherein the image forming means discharges ink onto a sheet to form an image having no margin. About.

[0002]

2. Description of the Related Art As an example of a conventional image forming apparatus, a sheet stored in a sheet storage unit is moved by a sheet conveying means.
2. Description of the Related Art There is an ink jet recording apparatus configured to form an image by being conveyed below a print head that is an image forming unit that reciprocates in a direction perpendicular to a sheet conveying direction.

As such a conventional ink jet recording apparatus, for example, as shown in FIG. 11, a print head 31 of an ink jet system, a pair of conveying rollers 32 provided upstream of the print head 31 in the conveying direction, A pair of paper discharge rollers 35 provided on the downstream side, a fixed platen means 38 provided immediately below the print head 31, provided on the upstream side in the transport direction of the pair of transport rollers 32, and a sheet facing the pair of transport rollers 32. Pickup roller 3 that sends out S
9 and the like are generally known.

Here, a pair of transport rollers 32 on the upstream side in the transport direction of the print head 31 includes a transport roller 33 having a surface layer having a high friction coefficient such as a rubber layer on an outer peripheral surface, and a transport roller 33 and a sheet transport path. And a pinch roller 34, which is rotatably provided at a position facing each other with the pressing member in contact with the transport roller 33 by a pressing means (not shown).

A pair of paper discharge rollers 35 on the downstream side in the transport direction of the print head 31 includes a paper discharge roller 36 having a surface layer parallel to the transport roller 33 and having a high friction coefficient like the transport roller 33. The discharge roller 36 is rotatably provided at a position opposed to the discharge roller 36 with the sheet conveying path interposed therebetween, and includes a spur 37 pressed against the discharge roller 36 by pressing means (not shown).

The fixed platen means 38 is used to maintain the posture of the sheet S conveyed to a position directly below the print head 31 by the conveying roller pair 32 and the gap (gap) between the print head 31 and the sheet S. Sheet supporting portion 38a. The sheet supporting portion 38a is formed of a rib-shaped member having a small surface or contact area, and the height of the sheet supporting portion 38a is a pressure contact portion (nip portion) n1 between the transport roller 33 and the pinch roller 34. And a sheet conveyance path connecting the paper discharge roller 36 and the press contact portion n2 between the spur 37.

In the ink jet recording apparatus thus configured, when performing a printing (image forming) operation on the sheet S, first, the pickup roller 39 and the conveying roller 33 rotate in the sheet conveying direction shown by the arrow. . When the transport roller 33 rotates in this manner, the pinch roller 34 pressed by the transport roller 33 also rotates by the frictional force with the outer peripheral surface of the transport roller 33.

As a result, when the sheet S is sent from the pickup roller 39 to the conveying roller pair 32, the sheet S is pressed into a pressure contact portion n1 between the conveying roller 33 and the pinch roller 34.
And is conveyed to a recording area below the print head 31 by a frictional force generated by a pressing force of the pinch roller 34 against the conveying roller 33.

Thereafter, the sheet S thus conveyed to the recording area is supported on its lower surface by the sheet supporting portion 38a of the platen means 38, and conveyed to a predetermined printing start position while maintaining an appropriate posture and gap. The print head 31 prints one line.

Next, when printing for one line is performed in this manner, one line of paper is fed by the conveying roller pair 32, and
As a result, the sheet S moves in the direction of the paper discharge roller pair 35, and the leading end reaches the press contact portion n2 between the paper discharge roller 36 and the spur 37. Is done.

The rotation speed of the paper discharge roller 36 is adjusted so that the recording portion of the sheet S is given an appropriate tension.
The rotation speed is slightly increased. At this time, the relationship between the transporting force (frictional force) between the transporting roller pair 32 and the paper discharging roller pair 35 is as follows: transporting roller pair 32> paper discharging roller pair 35.

When the trailing edge of the sheet S passes through the pair of conveying rollers 32, the sheet S is discharged only by the pair of discharge rollers 35.
Then, when the trailing edge of the sheet S passes through the recording area, the printing is completed, and the sheet S is discharged to the outside of the apparatus by the discharge roller pair 35.

[0013]

By the way, in such a conventional ink jet recording apparatus, when the sheet is conveyed, the sheet S may be displaced due to a dimensional deviation of the sheet itself, a deviation due to a setting method, or a sheet conveyance accuracy. In some cases, the print head 31 is conveyed below the print head 31 in a shifted state. When ink is ejected from the print head 31 to a sheet in such a displaced state, ink is ejected to a portion where the sheet does not exist, and as a result, the ink adheres to the platen means.

In order to prevent the platen means from being stained even when the sheet is conveyed in such a shifted state, for example, as shown in FIG. Was to be provided. That is,
The relationship between the printing range and the sheet size is set so that the printing range <the sheet size as shown in FIG.

However, there has been a growing demand for marginless (no border) printing due to the diversification of printer demand in recent years, and there has been a growing demand for marginless printing in ink jet recording apparatuses from the viewpoint of resource saving for effective use of sheets. Printing is mandatory. Here, when marginless printing is to be performed, the relationship between the printing range and the sheet size needs to be such that printing range> sheet size as shown in FIG. 13 in consideration of the dimensional deviation of the sheet itself as described above. There is. Specifically, a printing range of about the sheet size + 3 mm is required in consideration of the deviation of the dimensions of the sheet itself.

However, when the printing range exceeds the sheet size, that is, when the printing range is enlarged, ink is ejected from the sheet S, and the ink is discharged from the platen as described above. Becomes attached to the means. When ink adheres to the platen means in this way, not only does the apparatus become dirty and impairs aesthetics, but also a large amount of ink adheres to the back side of the sheet immediately after being conveyed to the printing area, and the sheet back surface becomes dirty. There was a problem that would be.

Accordingly, the present invention has been made in view of such a problem, and it is an object of the present invention to effectively prevent contamination of the apparatus and adhesion of ink to the back surface of a sheet even when marginless printing is performed. It is an object of the present invention to provide an ink jet recording apparatus (image forming apparatus) that can perform the following.

[0018]

According to the present invention, there is provided a sheet conveying means for conveying a sheet, and ink is ejected to a sheet conveyed downward by the sheet conveying means while moving in a direction orthogonal to the sheet conveying direction. And a plurality of spurs provided below the image forming means and supporting the conveyed sheet from below, and a plurality of spurs below the plurality of spurs. And an ink absorbing means for absorbing the ink not attached to the sheet among the inks ejected from the image forming means.

In the present invention, the ink absorption means may protrude forward in a sheet conveying direction from a leading end position of the sheet when image formation is started, and may convey a sheet more than a rear end position of the sheet when image formation ends. Projecting backward in the direction
Further, the sheet has a shape protruding from both side edges of the sheet in a direction orthogonal to the sheet conveying direction.

Further, the present invention is characterized in that the plurality of spurs are provided with cleaning means for cleaning the surfaces of the spurs.

Further, the present invention is characterized in that the plurality of spurs are formed of a water-repellent material.

Further, the present invention is characterized in that the surfaces of the plurality of spurs are subjected to a water-repellent treatment.

Further, as in the present invention, after the sheet is conveyed below the image forming means by the sheet conveying means, ink is ejected on the sheet while the image forming means is moved in a direction orthogonal to the sheet conveying direction. Thus, an image is formed on the sheet. At this time, the conveyed sheet is supported from below by a plurality of spurs provided below the image forming means, and ink ejected from the image forming means by ink absorbing means provided below the plurality of spurs. Absorb the ink not attached to the sheet.

[0024]

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

FIG. 1 is a perspective view showing the structure of an ink jet recording apparatus as an example of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a side view thereof.

1 and 2, reference numeral 1 denotes an ink jet recording head (hereinafter, referred to as a recording head), and reference numeral 2 denotes a carriage for holding the recording head 1. The carriage 2 is mounted on a guide shaft 3 by driving a motor (not shown). Along the direction perpendicular to the sheet conveying direction, that is, in the width direction (main scanning direction) of the sheet S.

The recording head 1 ejects ink in accordance with an image signal while moving with the carriage 2 so that printing (image formation) is performed on the sheet S. Has become. That is, the recording head 1 and the carriage 2 constitute an image forming unit that forms an image by ejecting ink while moving the sheet S in a direction orthogonal to the sheet conveying direction.

In FIG. 1, reference numeral 4 denotes a conveying roller for conveying the sheet S. The conveying roller 4 is rotatably supported by a chassis (not shown) on the upstream side of the recording head 1 in the conveying direction. It is connected to a pulse motor (not shown) and is driven to rotate. Here, in the present embodiment, rubber is provided on the surface of the transport roller 4 in order to form a surface layer having a high coefficient of friction.

Incidentally, in recent years, as the transport roller 4, in order to improve the transport accuracy of the sheet S of the transport roller 4, A
l, SUS, SUM material is ground and blasted to increase the surface friction, urethane and other resins are applied, alumina, ceramic and other particles are attached. A transport roller having such a configuration may be used.

On the other hand, a plurality of rotatable pinch rollers 5 which constitute a sheet conveying means together with the conveying roller 4 are provided at positions opposing the conveying roller 4 with the sheet conveying path therebetween. It is pressed against the transport roller 4 by a pressing means (not shown). A pickup roller 6 and the like for picking up the sheet S and conveying the sheet S to the conveyance roller 4 are provided on the upstream side of the conveyance roller 4 in the conveyance direction.

In FIG. 1, reference numeral 7 denotes a discharge roller provided downstream of the recording head 1 in the direction of conveyance in parallel with the conveyance roller 4. The discharge roller 7 is rotatably mounted on a chassis (not shown). The shaft is supported, and rubber is provided on the surface. Here, the discharge roller 7 is connected to a pulse motor (not shown) and is driven to rotate similarly to the transport roller 4.
In order to apply an appropriate tension to the recording portion of the sheet S, the rotation speed of the discharge roller 7 is slightly higher than the rotation speed of the conveyance roller 4.

A plurality of rotatable spurs 8 are provided at positions facing the paper discharge roller 7, and the spurs 8 are pressed by a suitable pressing force against the paper discharge roller 7 by pressing means (not shown). Pressed. Here, the relationship of the conveying force (frictional force) between the conveying roller pair including the conveying roller 4 and the pinch roller 5 and the discharging roller pair including the discharging roller 7 and the spur 8 is as follows. It is set to be a roller pair.

Reference numeral 9 denotes a platen spur which is rotatably mounted directly below the recording head 1 and which supports the lower surface of the sheet S conveyed below the recording head 1 by a pair of conveying rollers. Yes, this platen spur 9
Thereby, the sheet S can maintain a suitable posture and a predetermined gap (gap) between the recording head 1.

In the present embodiment, the platen spur 9 is thin and has a pointed tip so as to reduce the contact area with the sheet S as shown in FIG. Here, by forming the platen spur 9 in such a shape, when performing marginless printing as described later, that is, when printing is performed in a printing range larger than the sheet size, the front end and rear end of the sheet are used. When printing on a set, even if a part of the ink ejected out of the sheet S and not attached to the sheet S adheres to the platen spur 9, the amount of the attached ink can be reduced.

By thus reducing the amount of ink adhered and by reducing the contact area with the sheet S, a large amount of ink adhered to the platen spur 9 can be applied to the back of the sheet when performing marginless printing. To prevent the sheet back surface from being stained.

On the other hand, below the platen spur 9, an ink absorbing means 10 provided with an absorbing material such as sponge is provided. Here, the ink absorbing unit 10 protrudes forward in the sheet conveying direction from the sheet leading end position when image formation is started, and projects rearward in the sheet conveying direction from the sheet rear end position when image forming ends, The sheet has a shape that protrudes from both side edges of the sheet in a direction orthogonal to the sheet conveying direction.

By providing the ink absorbing means 10 below the platen spur 9 as described above, when performing marginless printing, the ink discharged to the leading edge, the trailing edge, and the outside of the left and right ends of the sheet is used as the ink. The recording head 1 can be absorbed by the absorbing means 10 and can be absorbed in the apparatus main body, particularly, in the recording head 1.
Can be effectively prevented from becoming dirty below.

Next, the marginless printing operation in the ink jet recording apparatus having such a configuration will be described.

When the marginless printing operation is started, first, the sheet S picked up by the pickup roller 6 is conveyed to the press contact portion n1 between the conveying roller 4 and the pinch roller 5 shown in FIG.

Here, since the sheet S receives the pressing force of the pinch roller 5 due to the pressing force of the pressing means (not shown) at the pressing portion n1, the sheet S is moved between the outer peripheral surface of the transport roller 4 which is driven to rotate and the sheet S. The sheet S is conveyed to a predetermined printing start position below the recording head 1 by the frictional force.

At this time, since the lower surface of the sheet S is supported by the platen spur 9 as shown in FIGS. 4 and 5, a suitable posture and a predetermined gap (gap) with the recording head 1 are maintained. be able to.

Thereafter, the carriage 2 is moved in the main scanning direction with respect to the sheet S, and ink is ejected from the recording head 1 to print one line. Each time one line is printed, one line of paper is fed.

Here, when performing marginless printing, as shown in FIG. 13 described above, the printing range is set to be larger than the sheet size in consideration of the dimensional variation of the sheet S and the like. Therefore, a part of the ink ejected from the recording head 1 is ejected off the leading end and the side end of the sheet S.

However, the ink ejected off the leading end and the side end of the sheet S is provided below the platen spur 9 and is located forward of the sheet leading end position when image formation is started in the sheet conveying direction. And the sheet S
Since the ink is absorbed by the ink absorbing means 10 having such a shape as to protrude from both side edges in the direction perpendicular to the sheet conveying direction, the apparatus is not stained.

The ink discharged ahead of the leading end of the sheet S adheres to the leading end of the platen spur 9, but since the platen spur 9 has a thin, pointed shape, the ink adhesion amount And the contact area of the platen spur 9 with the sheet S is also small, so that a large amount of the ink S is not transferred to the sheet rear surface and the sheet rear surface is not stained.

On the other hand, after the leading edge of the sheet S is conveyed to the printing start position, the sheet S, which has been fed by one line each time one line is printed, moves in the direction of the paper discharge roller 7 and eventually reaches the leading end. Is a pressure contact portion n2 between the discharge roller 7 and the spur 8.
After that, the sheet S is conveyed by a pair of conveying rollers and a pair of paper discharging rollers as shown in FIG.

Even when the sheet is conveyed by the conveying roller pair and the paper discharging roller pair, the ink discharged from the side edge of the sheet S is discharged from the platen spur 9 as shown in FIG. Since the ink is absorbed by the ink absorbing means 10 located below, the device is not soiled as described above.

Thereafter, when the trailing end passes through the conveying roller pair,
The sheet S is conveyed by a pair of paper discharge rollers.
Then, when the trailing edge of the sheet S reaches below the recording head 1 as shown in FIGS. 8 and 9, ink is ejected to the trailing edge.
A part of the ink discharged from the sheet S is discharged from the rear end and the side end of the sheet S.

However, the ink ejected off the side edge of the sheet S and not attached to the sheet S projects rearward in the sheet conveying direction from the sheet rear end position when the image formation is completed, and Since the ink is absorbed by the ink absorbing means 10 having a shape protruding from both side edges of the sheet S in a direction perpendicular to the sheet conveying direction, the apparatus is not stained.

The ink ejected rearward from the rear end of the sheet S adheres to the leading end of the platen spur 9, but the amount of ink adhering to the platen spur 9 is small. Since the contact area is small, the ink S
Is transferred to the back of the sheet in a large amount, and the back of the sheet is not stained.

After that, the sheet S is conveyed only by the pair of paper discharge rollers, and when the trailing end of the sheet S passes through the recording area, the printing is completed. Is discharged.

As described above, since the sheet S is supported by the plurality of platen spurs 9 and the ink absorbing means 10 is provided below the platen spur 9, even when printing without margins is performed, contamination of the apparatus and the back surface of the sheet can be achieved. It is possible to effectively prevent ink from adhering to the surface.

If the platen spur 9 is formed of a water-repellent material or the surface thereof is subjected to a water-repellent treatment, it is possible to make it more difficult for ink to adhere to the tip of the platen spur 9 and to apply the ink to the sheet back surface. Adhesion of ink can be more effectively prevented.

Further, for example, as shown in FIG. 10, if the platen spur 9 is provided with cleaning means 11 for cleaning the ink adhering to the tip of the platen spur 9, if the cleaning means 11 is attached to the tip of the platen spur 9, The ink can be removed, so that the ink does not adhere to the back surface of the sheet. Here, the cleaning means 11 does not need to be always in contact with the platen spur 9, but may be in contact with the platen spur 9 at a predetermined timing.

In the above description, the case where the platen spurs 9 are provided in a row below the recording head 1 has been described. However, the present invention is not limited to this, and a plurality of platen spurs 9 may be provided as necessary. A row may be provided. In the above description, the inkjet recording apparatus itself has been described as an example. However, the present invention is not limited to this, and may be applied to an inkjet recording apparatus incorporated in a copier, a printer, a facsimile, or the like. Can be applied.

[0056]

As described above, according to the present invention, the conveyed sheet is supported from below by a plurality of spurs provided below the image forming means, and is provided below the plurality of spurs. The ink absorbing unit absorbs the ink that has not adhered to the sheet out of the ink ejected from the image forming unit, so that even if marginless printing is performed, the device is stained and the ink adheres to the back surface of the sheet. Can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an ink jet recording apparatus as an example of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of the ink jet recording apparatus.

FIG. 3 is a conceptual diagram of a platen spur provided in the inkjet recording apparatus.

FIG. 4 is a perspective view showing a state in which printing is performed on the leading end of a sheet during marginless printing of the inkjet recording apparatus.

FIG. 5 is a side view illustrating a state in which printing is performed on the leading edge of a sheet during the marginless printing.

FIG. 6 is a side view illustrating a state in which printing is performed at the center of a sheet during the marginless printing.

FIG. 7 is a perspective view showing a state in which printing is performed on a central portion of a sheet during the marginless printing.

FIG. 8 is a perspective view showing a state in which printing is performed on a rear end portion of a sheet during the marginless printing.

FIG. 9 is a side view illustrating a state in which printing is performed on the rear end of the sheet during the marginless printing.

FIG. 10 is a perspective view illustrating a cleaning roller for cleaning a platen spur of the ink jet recording apparatus.

FIG. 11 is a side view showing a configuration of a conventional inkjet recording apparatus.

FIG. 12 is a diagram illustrating a sheet size and a print range.

FIG. 13 is a view for explaining a printing range in marginless printing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Carriage 4 Transport roller 5 Pinch roller 9 Platen spur 10 Ink absorption means 11 Cleaning means

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Claims (5)

[Claims] An image forming apparatus configured to form an image by ejecting ink while moving a sheet conveyed downward by the sheet conveying means in a direction orthogonal to a sheet conveying direction; A plurality of spurs provided below the image forming means and supporting the conveyed sheet from below, and the image forming means provided below the plurality of spurs. An ink absorbing unit that absorbs ink that has not adhered to the sheet out of the ink ejected from the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the ink absorbing unit protrudes forward in a sheet conveying direction from a sheet leading end position when image formation is started, and is rearward in a sheet conveying direction from a sheet rear end position when image forming ends. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus has a shape that protrudes and protrudes from both side edges of the sheet in a direction orthogonal to the sheet conveying direction. 3. An image forming apparatus according to claim 1, wherein said plurality of spurs are provided with a cleaning means for cleaning a surface of said spurs. 4. The image forming apparatus according to claim 1, wherein the plurality of spurs are formed of a water-repellent material. 5. The image forming apparatus according to claim 1, wherein the surface of the plurality of spurs is subjected to a water-repellent treatment.