JP3629869B2 - Inkjet printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inkjet printer. In particular, the present invention relates to the paper discharge structure.
[0002]
[Prior art]
In general, inkjet printers print by ejecting ink droplets on a sheet of paper, so when printing on multiple sheets of paper continuously, the next sheet must be printed before the ink on the printed sheet has dried. There is a problem that the printed surface becomes dirty when it is slid and comes into sliding contact with the printed surface of the printed paper.
[0003]
An ink jet printer described in Japanese Patent Laid-Open No. 6-91861 is known as an attempt to solve such a problem.
[0004]
FIG. 3 is a sectional side view of the printer. This inkjet printer includes an automatic paper feeder 1 that feeds paper P, a path 3 of paper fed by a paper feed roller 2 of the automatic paper feeder 1, and a paper feed roller that winds and conveys the paper. 4, an ink jet head (hereinafter simply referred to as a “head”) that is mounted on a pinch roller 5 that is driven by pressure contact with the paper feed roller 4 and a carriage 6 that reciprocates in a direction perpendicular to the paper surface. 7), a pair of discharge rollers 8a and 8b for conveying and discharging the sheet printed by the head 7, and both sides of the sheet discharged by the pair of discharge rollers 8a and 8b as shown in FIG. There are provided ribs 9a and 9b for instructing from below, and a push-down serrated roller (thin plate-like star wheel) 9c for pushing down a substantially central portion of the sheet from above.
[0005]
Therefore, according to this printer, the paper P printed by the head 7 and discharged by the discharge roller pair 8a, 8b is supported at the both sides thereof by the ribs 9a, 9b as shown in FIG. The part is discharged so as to be pushed downward by the push-down jagged roller 9c. That is, as shown in the figure, the paper P is forcibly urged into a concave shape when viewed from the discharge direction, and becomes stiff and conveyed in a floating state. The time until the paper P is brought into sliding contact with the printing surface of the paper (not shown) that has been printed and discharged first is delayed, and the time for the ink on the printed paper to dry is secured.
[0006]
Therefore, even when printing is continuously performed on a plurality of sheets of paper, there is no possibility that the next sheet slides on the printing surface before the ink on the printed sheet is dried and the printing surface becomes dirty.
[0007]
[Problems to be solved by the invention]
In the conventional printer described above, there is no problem when the paper is placed vertically, that is, when the printing direction is made to match the conveyance direction and the longitudinal direction of the paper. It has been found that the following problems occur when printing and discharging are performed such that the transport direction and the longitudinal direction of the paper are perpendicular to each other.
[0008]
That is, when ink droplets are ejected by the head and printed, and the paper absorbs ink droplets (moisture or liquid content thereof), the paper curls into a convex shape in FIG. 3 (the leading end of the paper faces downward as it is conveyed). The reaction of this curling force causes the sheet to approach the head 7 below the head 7, and the distance between the head 7 and the sheet becomes narrower than the proper distance, resulting in a deterioration in print quality. In the extreme case, there was a problem that the printing surface was soiled by the paper contacting the head 7.
[0009]
In addition, it is considered that the curl is more strongly generated when printing is performed in the landscape orientation than when printing in the portrait orientation because of the direction of the fibers forming the paper.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet printer that solves the above-described problems and does not cause deterioration of print quality and smearing of the print surface due to head rubbing even when printing is performed with the paper placed in a landscape orientation. is there.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an ink jet printer according to claim 1 is a printer that discharges ink droplets onto a sheet with a head to perform printing, and then discharges the sheet.
The upper and lower rollers temporarily convey the paper printed by the head downward from the print surface by the head, and the rotation center of the roller above the perpendicular passing through the rotation center of the lower roller is the paper. A first discharge roller pair biased downstream in the transport direction;
This roller is composed of upper and lower rollers that convey and discharge the sheet conveyed by the first pair of discharge rollers upward in the horizontal direction, and the rotation center of the roller above the vertical line passing through the rotation center of the lower roller is A second discharge roller pair biased upstream in the paper transport direction;
A sheet guide surface formed in an upwardly inclined manner from a lower downstream side with respect to the sheet conveying direction toward a contact portion between the second discharge roller pairs from a lower downstream side than a contact portion between the first discharge roller pairs. When,
It is characterized by having.
[0012]
[Function and effect]
According to the first aspect of the present invention, the paper printed by the head is first transported downward from the print surface by the head by the first discharge roller pair, and then the second discharge roller. The pair is transported upward from the horizontal direction and discharged.
[0013]
That is, the paper printed by the head is first transported downward from the print surface by the head, so the paper curls in a convex shape (curls so that the leading edge faces downward as it is transported). ) Even if a tendency is generated, the force that causes the paper to approach the head below the head does not occur or even if it occurs, it becomes small. In other words, the first discharge roller pair conveys the paper so as not to oppose the paper to be curled.
[0014]
Therefore, even if the paper does not approach or approaches the head, the amount of the paper becomes small. As a result, even if the paper is printed in the horizontal state, the print surface is deteriorated and the print surface is rubbed due to head rubbing. Dirt is not generated.
[0015]
Here, assuming that the paper is transported as above by the first discharge roller pair and is only discharged, the curl of the paper is not corrected, and thus printing is continuously performed on a plurality of sheets. There is a risk that the discharged paper will come into sliding contact with the printing surface of the previously printed and discharged paper that has not yet been dried. Also, in extreme cases, the discharged paper may even be curled by the curl.
[0016]
On the other hand, according to the ink jet printer of claim 1, the paper printed by the head is first transported downward by the first discharge roller pair downward from the printing surface by the head. In the next stage, the second discharge roller pair conveys the sheet upward from the horizontal direction and discharges it, so that the curl is corrected by the second discharge roller pair. In addition, since the paper is transported and discharged upward from the horizontal direction, the time until the leading end of the paper comes into sliding contact with the print surface of the paper that has been printed and discharged is delayed. This ensures the time for the ink to dry.
[0017]
Therefore, according to the ink jet printer of the first aspect, even when the paper is used in a horizontal state, the discharged paper is not curled by the curl and is continuous with a plurality of papers. Even when printing is performed, the ink on the printed paper does not dry, and the next paper does not slide on the printing surface and the printing surface is not soiled.
[0018]
As described above, according to the ink jet printer of the first aspect, even when printing is performed with the paper placed in the horizontal position, the print surface is not deteriorated and the print surface is not smudged due to head rubbing, and is discharged at the same time. The curled paper is no longer curled by the curl, and even when printing on multiple sheets of paper, the next paper slides on the print surface before the ink on the printed paper has dried. The printed surface is not soiled by contact.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a side sectional view of a main portion showing an embodiment of an ink jet printer according to the present invention, FIG. 2 (a) is a plan view showing first and second discharge roller pairs, and FIG. It is a front view of 2 discharge roller pairs.
[0021]
In these drawings, mainly in FIG. 1, 10 is a paper feed roller, 11 is a pinch roller, 12 is an ink jet head, and the paper feed roller 3, pinch roller 5 and ink jet head 7 in the conventional printer shown in FIG. Each corresponds.
[0022]
Accordingly, the paper P is supplied from, for example, an automatic paper feeder not shown in FIG. 1 and is conveyed while being pinched by the paper feed roller 10 and the pinch roller 11, and at the feed angle (feed-out) by the pinch roller 11. Direction) is defined and conveyed below the head 12. The head 12 is mounted on a carriage (not shown) and prints on paper by ejecting ink droplets while reciprocating in a direction orthogonal to the paper surface. A region indicated by A in the figure is a printing region, and ink droplets are ejected in this region. Below the printing area A, there is a rib 42 that is integrally provided on the upper surface of the frame 40, which will be described later, so that the rib 42 contacts the back surface of the paper to define the distance between the paper and the head 12. It has become. The downstream side portion 42a of the printing area A of the rib 42 is sharply inclined downward in the vicinity of the downstream side of the printing area A so as not to interfere with the curling of the paper described later. Reference numeral 13 denotes a substrate of the head 12, which is fixed to a carriage (not shown) so that the head 12 is mounted on the carriage.
[0023]
A first discharge roller pair 20 and a second discharge roller pair 30 are provided on the downstream side (left side in the drawing) of the print area A in the paper conveyance direction.
[0024]
The first discharge roller pair 20 includes a plurality of drive rollers 22, 22,... (See FIG. 2A) fixed to a shaft 21, and a serrated roller that is driven to rotate while being in pressure contact with the drive roller 22. (Thin plate-shaped star foil) 23, 23,. The shaft 21 is rotatably supported by the frame 40 and is rotationally driven by a driving mechanism (not shown). The drive roller 22 is constituted by a rubber roller or the like. The serrated roller 23 is supported by a holder 24 so as to be rotatable about a coil spring 25, and is pressed against and driven by the driving roller 22 by the elastic force of the coil spring 25 itself. Therefore, although not shown in detail, the coil spring 25 supports the serrated roller 23 rotatably in a state of being bent in a convex shape in FIG. The holder 24 is fixed to the lower surface of a frame (not shown). Further, the inclined surface 24a on the front surface of the holder 24 serves as a guide surface for guiding the leading edge of the paper.
[0025]
As shown in FIG. 1, the first discharge roller pair 20 as described above causes the paper P printed by the head 12 to be below the print surface (print surface in the print area A) P <b> 1 by the head 12 (that is, the print surface A). It is once transported in a direction away from the head 12.
[0026]
The second discharge roller pair 30 basically has the same configuration as the first discharge roller pair 20, and a plurality of drive rollers 32, 32,... Fixed to the shaft 31 (FIG. 2). (See (a)) and a jagged roller (thin plate-like star wheel) 33, 33,... The shaft 31 is rotatably supported by the frame 40 and is rotationally driven by a driving mechanism (not shown). The drive roller 32 is constituted by a rubber roller or the like. The serrated roller 33 is supported by a holder 34 so as to be rotatable about a coil spring 35, and is pressed against and driven by the elastic force of the coil spring 35 itself. The holder 34 is fixed to the lower surface of a frame (not shown). Further, the inclined surface 34a on the front surface of the holder 34 is a guide surface for guiding the leading edge of the paper. The guide surface 34a normally does not play a role, that is, as described above, the sheet P is conveyed downward by the first discharge roller pair 20, and therefore usually does not serve as a guide. If the leading edge of the sheet is curved upward for some reason, the leading edge of the sheet is brought into contact with this to guide the leading edge of the sheet toward the jagged roller 33.
[0027]
As shown in FIG. 1, such a second discharge roller pair 30 conveys and discharges the paper P conveyed by the first discharge roller pair 20 upward from the horizontal direction. Yes.
[0028]
Note that the upper surface 41 of the frame 40 positioned between the first discharge roller pair 20 and the second discharge roller pair 30 allows the sheet P conveyed by the first discharge roller pair 20 to be transferred to the second discharge roller. A guide surface for guiding toward the pair 30 is formed.
[0029]
According to the ink jet printer as described above, the paper P printed by the head 12 is first transported downward from the print surface P1 by the head 12 by the first discharge roller pair 20, and then the first The two discharge roller pairs 30 are transported upward from the horizontal direction and discharged.
[0030]
That is, the paper P printed by the head 12 is first transported downward from the print surface P1 by the head 12, so that the paper P curls in a convex shape (the leading edge thereof is lowered downward as it is transported). Even if a tendency to curl so that the paper P approaches the head 12 below the head 12 does not occur, or even if it occurs, it becomes small. In other words, the first discharge roller pair 20 conveys the paper P so as not to oppose the paper P to be curled.
[0031]
Therefore, even if the paper P does not approach the head 12 in the print area A or approaches, the amount of the paper P becomes small. As a result, even if the paper P is printed in the landscape orientation, the print quality is reduced. The print surface is not smeared due to deterioration of the print head and rubbing of the head.
[0032]
Here, assuming that the sheet P is only conveyed and discharged by the first discharge roller pair 20 as above, curling of the sheet P is not corrected, and therefore, the sheet P is continuously applied to a plurality of sheets. In the case of printing, there is a possibility that the discharged paper P may come into sliding contact with the printing surface of the paper that has been printed and discharged (see the virtual line P ′ in FIG. 1) that has not yet been dried, and may contaminate it. is there. Also, in extreme cases, the discharged paper may even be curled by the curl.
[0033]
On the other hand, according to the ink jet printer of this embodiment, the paper P printed by the head 12 is first conveyed by the first discharge roller pair 20 downward from the printing surface P1 by the head 12. However, in the next stage, the second discharge roller pair 30 is transported and discharged upward in the horizontal direction, so that the curl is corrected by the second discharge roller pair 30. . Moreover, since the paper P is transported and discharged upward in the horizontal direction, the time until the leading end of the paper P comes into sliding contact with the printing surface of the paper P ′ that has been printed and discharged is delayed. The time for the ink on the printed paper P ′ to dry is secured.
[0034]
Therefore, according to the ink jet printer, even when the paper is used in a horizontal state, the discharged paper P is not curled by the curl and is continuously printed on a plurality of sheets. However, there is no possibility that the next paper P is brought into sliding contact with the printing surface before the ink on the printed paper P ′ is dried, and the printing surface is soiled.
[0035]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the gist of the present invention.
[0036]
【The invention's effect】
According to the ink jet printer of the first aspect, even when printing is performed with the paper placed in a horizontal state, the print quality is not deteriorated and the print surface is not soiled due to head rubbing, and the discharged paper is curled by the curl. In addition, even when printing on multiple sheets of paper continuously, the ink on the printed paper does not dry before the next paper comes into sliding contact with the print surface and the print surface becomes dirty. It will not happen.
[0037]
[Brief description of the drawings]
FIG. 1 is a side sectional view of a main portion showing an embodiment of an ink jet printer according to the present invention.
FIG. 2A is a plan view showing a first and second discharge roller pair, and FIG. 2B is a front view of the second discharge roller pair.
FIG. 3 is a side sectional view of a conventional printer.
FIG. 4 is an operation explanatory diagram of a conventional printer.
[Explanation of symbols]
P Paper P1 Printing surface 12 With head 20 First discharge roller pair 30 Second discharge roller pair

Claims (1)

A printer that ejects ink droplets onto a sheet with a head to print, and then ejects the sheet.
The upper and lower rollers temporarily convey the paper printed by the head downward from the print surface by the head, and the rotation center of the roller above the perpendicular passing through the rotation center of the lower roller is the paper. A first discharge roller pair biased downstream in the transport direction;
This roller is composed of upper and lower rollers that convey and discharge the sheet conveyed by the first pair of discharge rollers upward in the horizontal direction, and the rotation center of the roller above the vertical line passing through the rotation center of the lower roller is A second discharge roller pair biased upstream in the paper transport direction;
A sheet guide surface formed in an upwardly inclined manner from a lower downstream side with respect to the sheet conveying direction toward a contact portion between the second discharge roller pairs from a lower downstream side than a contact portion between the first discharge roller pairs. When,
An ink jet printer comprising:

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