JP3561428B2 - Inkjet printer - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides an ink head that ejects ink droplets on a recording paper based on image information to print an image, a paper feed roller that feeds the recording paper to a print area by the ink head, and a paper that is printed by the ink head. The present invention relates to an ink jet printer including a discharge roller for discharging recording paper.
[0002]
[Prior art]
In an inkjet printer that forms an image by ejecting ink droplets from an ink head to recording paper based on image information, the recording paper fed to a printing area is used to stabilize the print quality of printing on the recording paper. The recording paper must be conveyed so that the distance between the paper and the ink head is kept constant and the state of ink droplet adhesion is always the same.
[0003]
As shown in FIG. 11 , the ink jet printer performs printing by reciprocatingly scanning the ink head 31 with respect to the recording paper P and attaching ink droplets ejected from the ink head 31 to the recording paper P.
[0004]
Therefore, the flight direction of the ink droplet ejected from the ink head coincides with the composite vector of the scanning vector of the carriage for reciprocating the ink head and the ejection vector from the ink head, and the flying direction of the ink droplet is oblique. become.
[0005]
That is, when the ink head is moving in the illustrated arrow (forward) direction, the ink droplet ejected from the ink head exerts a force on the recording paper P side and a force on the left side in the drawing. When the ink head flies in the direction indicated by the alternate long and short dash line by the vector and moves in the direction of the arrow (return) shown in the figure, the ink droplets ejected from the ink head are caused by the force toward the recording paper P and the rightward direction in FIG. Is applied, and it flies in the direction indicated by the two-dot chain line by the vector of both forces.
[0006]
The distance in which the ink droplets adhere to the recording paper P in the horizontal direction increases as the ink-jet printer operates at a higher speed because the reciprocal scanning speed of the ink head increases . As shown in FIG. If the distance (interval) between the head and the ink head is always kept constant, as in the case where the paper P does not rise, the ink droplets on the recording paper P during the forward scan and the backward scan are kept. Although matching without departing attachment point Z, if there is floating on the recording paper P as shown in FIG. 11 (b), the attachment points Z ₁ of the ink droplets at the time of the forward scanning of the ink head, the ink head backward scanning becomes mismatched rise to off and attachment point Z ₂ of the ink droplet when, a reduction in print quality.
[0007]
Therefore, as a method of transporting the recording paper P while maintaining a constant distance between the ink head and the recording surface of the recording paper P, the recording paper P to be transported is transported by the feed roller and the discharge roller. At this time, set the paper discharge speed by the paper discharge roller to be slightly higher than the paper feed speed by the paper feed roller, pull the recording paper by the paper discharge roller, and use the ink head to lift the recording paper due to slack in the print area. Some were preventing it.
[0008]
However, in recent ink-jet printers, in order to increase the speed, the configuration of the ink head has a plurality of rows of ink nozzles, which increases the width of the ink head. Cannot be arranged close to each other.
Therefore, in the above-described method, when the recording paper is nipped by the paper feed roller and is not nipped by the paper discharge roller, or when the recording paper is nipped by the paper discharge roller and not nipped by the paper feed roller, In some cases, looseness occurs on the side of the end portion that is not pinched, and the end portion is lifted, so that the distance between the recording paper and the ink head cannot always be conveyed at a constant distance.
[0009]
In order to solve such a problem, as disclosed in Japanese Patent Application Laid-Open No. H5-162881, a conductive roller stretched between a driving roller and a driven roller is provided between a paper feeding roller and a discharging roller. A belt is arranged, a voltage is applied to the conductive belt, and the recording paper is electrostatically attracted by electrostatic force, and the recording paper is conveyed while maintaining a certain distance from the ink head so as not to float up. There was something.
[0010]
[Problems to be solved by the invention]
However, when the recording paper is transported by electrostatic attraction as described above, since the recording paper is attracted to the conductive belt by electrostatic force, a structure for separating the recording paper from the conductive belt is required. In addition, the recording paper cannot be stably discharged by the discharge roller.
In addition, when special recording paper with doubled paper such as an envelope is conveyed as recording paper, the paper on the ink head side cannot be adsorbed and rises on the printing side (paper). There was a problem that occurs.
[0011]
The present invention has been made in view of the above problems, and sucks recording paper by sucking air in a printing area by an ink head, thereby reliably preventing floating of the recording paper and discharging the recording paper. It is an object of the present invention to provide an ink jet printer that can be stably operated.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, an ink jet printer according to the present invention includes an ink head that ejects ink droplets based on image information and prints an image on recording paper, and a paper feed that feeds recording paper to a print area by the ink head. Roller, and an ink jet printer having a paper discharge roller for discharging the recording paper printed by the ink head,
A plurality of transport rollers are disposed along the transport direction of the recording paper between the paper feed roller and the discharge roller including a print area by the ink head, and transport the recording paper,
A triangular prism-shaped side surface is disposed between the plurality of transport rollers so as to face the ink head, supports the transported recording paper together with the transport rollers, and sets a distance between the ink head and the recording paper. A plurality of support members so that is constant,
And suction means for sucking air from a gap between the conveyance roller and the support member and adsorbing recording paper toward the conveyance roller and the support member.
[0014]
In the ink jet printer of the present invention described above, the conveying rows la can be rotated driven by the rotation drive means of the discharge roller.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the ink jet printer of the present invention will be described with reference to FIGS.
[0016]
In this ink jet printer, a paper feed tray 2 for storing recording paper P is provided at a lower portion of a side surface of a printer main body 1, and a discharge tray 3 for discharging printed recording paper P is provided at an upper portion of a side surface of the printer main body 1. .
[0017]
The printer main body 1 includes a pickup roller 4 that picks up the recording paper P in the paper feed tray 2 one by one, a pair of paper feed rollers 5 that feeds the recording paper P picked up by the pickup roller 4, A conveyance path 7 that conveys the recording paper P conveyed by the roller 5 to a registration roller 6 serving as a pair of second paper feeding rollers, and the registration roller 6 causes the leading end of the image information to coincide with the leading end of the recording paper P An ink head 8 for ejecting ink droplets to the recording paper P fed by adjusting the paper feed timing and printing based on image information, and discharging the recording paper P printed by the ink head 8 to the paper output tray 3 A pair of paper discharge rollers 9 for performing paper feeding is provided.
[0018]
The ink head 8 is provided with a support shaft 10 that supports a carriage (not shown) that movably holds the ink head 8 for reciprocating scanning in a direction orthogonal to the paper feeding direction of the recording paper P.
[0019]
Then, the suction device 11 that sucks the recording paper P into the printing area of the ink head 8 between the registration roller 6 and the paper discharge roller 9 by suctioning air so that the recording paper P is spaced from the ink head 8 at a fixed distance is provided. Provided.
[0020]
The printing operation of the above configuration will be described. The uppermost sheet of the recording paper P stored in the paper feeding tray 2 is picked up by the pickup roller 4 and transported to the paper feeding roller 5. Is fed to the registration roller 6 through the conveyance path 7.
[0021]
The recording paper P is fed to the print area by adjusting the timing so that the leading end of the image information and the leading end of the recording paper P are aligned by the registration roller 6.
The recording paper P fed to the print area is sucked by the suction device 11 and once stopped in this print area while the distance from the ink head 8 is maintained at a constant distance.
[0022]
Then, the ink head 8 is reciprocally scanned by the carriage in a direction orthogonal to the paper feeding direction of the recording paper P, and ink droplets ejected from the ink nozzles of the ink head 8 adhere to the recording paper P to perform printing, When one line (one direction) of scanning by the ink head 8 is completed, the recording paper P corresponding to a plurality of rows of ink nozzles of the ink head 8 is conveyed, and printing is performed by the ink head 8 based on image information. The recording paper P on which the operation has been performed is discharged to the discharge tray 3 by the discharge rollers 9.
[0023]
In such an ink jet printer, a constant distance between the ink head 8 and the recording paper P leads to an improvement in print quality.
[0024]
First, the distance of Figure 3 is the ink head 8 and the recording sheet P, is performed printing in a state of being held a predetermined distance, ink droplets corresponding to each dot based on image information attached to the normal position This shows the state printed.
[0025]
However, in order to perform high-speed printing in recent years, the arrangement of ink nozzles in the ink head 8 has been increased (previously, MAX was about 100 nozzles, but recently about 300 nozzles. As the number of nozzles increases to about 1000 nozzles), the floating phenomenon of the recording paper P during printing becomes a serious problem, and if the “floating” phenomenon occurs in the recording area of the recording paper P, as shown in FIG. In this manner, printing is performed from the target attachment point (X) on the recording paper P to a point (Y) corresponding to the amount of floating of the recording paper P, and an adhesion point error occurs on the recording paper P (ΔX and ΔX). The printing point on the recording paper P differs depending on ΔY.) As a result, the printing points (points where ink droplets adhere) in the reciprocating scanning of the ink head 8 during printing are caused to be inconsistent, and the printing quality is reduced (see FIG. 11B ).
[0026]
As described above, when the phenomenon of “floating” of the recording paper P occurs, as shown in FIG. 5, the portion (A portion) of the recording paper P close to the ink head 8 is not an appropriate dot width but a dense state. Dot is printed. Further, a floating portion (C portion) having a slope from the A portion to the B portion which is the optimum position of the recording paper P is in a state where the dot pitch to be printed is irregularly arranged. That is, the state described in FIG. 4 is obtained.
[0027]
As a result, when printing is performed in one line, the printing of the above-mentioned part A is dark, there is a possibility that white spots may occur in the part C, and there is a problem that proper printing can be performed only in the part B.
[0028]
Further, the ink droplets ejected from the ink nozzles of the ink head 8 are initially subjected to the initial velocity, acceleration, and air resistance. However, as described above, the distance between the ink nozzles 8 and the recording paper P is reduced. If the ink droplets are different, the speed at which the ink droplets adhere to the recording paper P varies depending on the adhesion position, which may cause the ink droplets to scatter, thereby lowering the print quality. Therefore, as shown in FIG. The recording paper P in the printing area is suctioned by the suction device 11 so that the distance from the ink head 8 is constant.
[0029]
An embodiment of the present invention of the suction device 11 in the ink jet printer will be described with reference to FIG.
[0030]
As shown in FIG. 7, the suction device 11 includes a plurality of transport rollers 12 having a smaller diameter than the registration roller 6 and the discharge roller 9 in a printing area (between the registration roller 6 and the discharge roller 9). P is disposed so that the distance from the ink head 8 is constant, and a triangular prism-shaped support member 13 between the transport rollers 12 has a flat surface in contact with the recording paper P, and the ink head of the recording paper P An air suction passage 14 is provided below the conveyance roller 12 and the support member 13 so as to suck air in a printing area from between the conveyance roller 12 and the support member 13. Is provided.
The transport roller 12 is rotationally driven by a drive motor that is a driving unit that rotationally drives the paper discharge roller 9.
[0031]
In the suction device 11 of the first embodiment having the above configuration, when the recording paper P is fed from the registration roller 6, the conveyance roller 12 and the support member 13 are connected to each other through the air suction passage 14 by using suction or the like (not shown). The air in the printing area is sucked in from between and the back side of the recording paper P (the suction device 11 side of the recording paper P) is set to a negative pressure, whereby the recording paper P is sucked to the suction device 11 side and Adsorbed.
[0032]
At this time, since the back side of the recording paper P comes into contact with the transport roller 12 and the support member 13, no slack or the like occurs in the printing area, and the distance from the ink head 8 is maintained at a constant distance. With this fixed distance being maintained, ink droplets are ejected from the ink nozzles of the ink head 8 to perform printing.
[0033]
According to such a configuration, a plurality of rows of ink nozzles are arranged to increase the speed of the ink head 8, and if the print area is large (the distance from the registration roller 6 to the paper discharge roller 9) is long, recording is performed. Even if the recording paper P is easily deformed in the printing area due to the thickness of the paper P, the distance from the ink head 8 becomes constant in all the printing areas by being sucked by the suction device 11, and the flying distance of the ink droplets Are all at the same distance, and the ink droplets are printed at the regular printing points, thereby preventing the print quality from deteriorating.
[0034]
Further, since the recording paper P is transported by the plurality of transport rollers 12, the frictional resistance applied to the recording paper P by suction can be reduced, and the recording paper P is transported between the transport rollers 12 by the air suction passage 14. The support member 13 prevents the recording paper P from entering the recording paper P with the ink head 8 between the transport rollers 12.
[0035]
Since the transport roller 12 is driven by the same drive motor as the discharge roller 9, the recording paper P can be transported in a stable state while maintaining a constant distance from the ink head 8.
This is because the slack of the recording paper P can be suppressed by pulling and transporting the recording paper P by the discharge roller 9 rather than by feeding the recording paper P to the printing area by the registration roller 6. This is because the recording paper P can be conveyed in a more stable state when the conveyance roller 12 is rotationally driven based on the driving of the recording sheet P.
[0036]
A reference example according to the present invention of the suction device 11 in the ink jet printer will be described with reference to FIGS.
[0037]
As shown in FIG. 8, the suction device 11 is provided with a transport belt 16 stretched over a drive roller 15a and a driven roller 15b in a printing area (between the registration roller 6 and the discharge roller 9). Inside the belt 16, a decompression chamber 17 that sucks air in a printing area is provided.
[0038]
A suction port 17a for sucking air in the printing area by the negative pressure in the decompression chamber 17 is formed on a wall surface of the decompression chamber 17 on the printing area side. belt suction holes 16a for sucking is formed, the diameter R ₁ of the belt intake hole 16a of the conveyance belt 16 is formed in diameter smaller than the diameter R ₂ of the inlet openings 17a of the vacuum chamber 17.
[0039]
This is because the negative pressure in the decompression chamber 17 acts on the transport belt 16 when the air in the printing area is sucked in through the air intake holes 17a and the belt intake holes 16a by the negative pressure in the decompression chamber 17, and the transport belt 16 is depressurized. This is for the purpose of moving in a state of contact with the wall surface of the chamber 17.
The drive roller 15 a of the transport belt 16 is driven to rotate by a drive motor that is a drive unit that drives the paper discharge roller 9 to rotate.
[0040]
In the suction device 11 of the second embodiment having the above configuration, when the recording paper P is fed from the registration roller 6, the pressure inside the decompression chamber 17 becomes negative, and the printing area is set via the suction holes 17a and the belt suction holes 16a. The recording paper P is sucked to the suction device 11 side and sucked by the suction device 11 by sucking the air and making the back side of the recording paper P (the suction device 11 side of the recording paper P) a negative pressure.
[0041]
At this time, while the recording paper P is sucked, the transport belt 16 is also sucked into the decompression chamber 17 side, and the transport belt 16 is moved by the driving of the driving roller 15 a while being in contact with the wall surface of the decompression chamber 17. 17, the distance between the conveying belt 17 and the ink head 8 is constant, and the recording paper P adsorbed on the conveying belt 17 is not slack, and the distance from the ink head 8 is constant. The ink droplets are ejected from the ink nozzles of the ink head 8 and printing is performed while maintaining the predetermined distance.
[0042]
According to such a configuration, a plurality of rows of ink nozzles are arranged to increase the speed of the ink head 8, and if the print area is large (the distance from the registration roller 6 to the paper discharge roller 9) is long, recording is performed. Even if the recording paper P is easily deformed in the printing area due to the thickness of the paper P, the distance from the ink head 8 becomes constant in all the printing areas by being sucked by the suction device 11, and the flying distance of the ink droplets Are all at the same distance, and the ink droplets are printed at the regular printing points, thereby preventing the print quality from deteriorating.
[0043]
Further, since the belt suction hole 16a of the transport belt 16 is formed smaller than the suction hole 17a of the pressure reduction chamber 17, the suction force due to the negative pressure of the pressure reduction chamber 17 is applied not only to the recording paper P but also to the transport belt 16. As a result, the distance between the recording paper P and the ink head 8 due to the slack of the transport belt 16 does not differ within the printing area, and the distance between the recording paper P and the ink head 8 is maintained at a constant distance.
[0044]
【The invention's effect】
According to the present invention, the ink head has a plurality of rows of ink nozzles for speeding up, and even if the print area becomes longer in the recording paper conveyance direction , the recording paper is held by the suction means. By being sucked, the distance from the ink head can be kept constant in the printing area , and the flying distance of the ink droplets is all the same distance, and the ink droplets are printed at regular print points, and the print quality is improved. Prevents decline.
[0045]
Further, since the recording paper is conveyed by the plurality of conveyance rollers, the frictional resistance applied to the recording paper by suction can be reduced. The supporting member prevents the distance from being different in this portion, and the supporting member can keep the distance between the recording paper and the ink head constant between the transport rollers.
[0047]
Since the transport row La is driven by the same drive motor and the discharge roller, it is possible to convey the distance between the ink head while maintaining a predetermined distance in a stable state the recording sheet.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing an embodiment of an ink jet printer of the present invention.
FIG. 2 is a schematic sectional view showing a printing portion in the embodiment of the ink jet printer of the present invention.
FIG. 3 is an explanatory diagram illustrating an example in which printing is performed in a state where the recording paper does not rise in the ink jet printer.
FIG. 4 is an explanatory diagram illustrating a state in which a recording paper is lifted in the inkjet printer.
FIG. 5 is an explanatory diagram showing attachment points (attachment points) of ink droplets when printing is performed in a state in which the recording paper floats on an ink jet printer.
FIG. 6 is an explanatory diagram showing a state in which a recording paper having a lift is adsorbed in the ink jet printer.
7 is a sectional view showing an exemplary shape condition of the adsorption apparatus in the ink jet printer of the present invention.
FIG. 8 is a sectional view showing a reference example of the suction device of the ink jet printer of the present invention.
FIG. 9 is a plan view showing an intake hole formed in a wall surface of the decompression chamber in FIG. 8;
FIG. 10 is a plan view showing a belt suction hole formed in the transport belt of FIG. 8;
11A and 11B are diagrams illustrating a flight direction of an ink droplet due to reciprocal scanning of an ink head in an ink jet printer. FIG. 11A is an explanatory diagram illustrating an attachment point of an ink droplet in a state where a recording paper does not float, and FIG. () Is an explanatory diagram showing the attachment points of the ink droplets in a state where the recording paper is lifted.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Printer main body 2 Paper feed tray 3 Paper discharge tray 6 Registration roller 8 Ink head 9 Paper discharge roller 11 Suction device 12 Transport roller 13 Support member 14 Air intake passage

Claims (2)

An ink head that ejects ink droplets based on image information to print an image on recording paper, a paper feed roller that feeds recording paper to a print area by the ink head, and discharges the recording paper printed by the ink head An ink jet printer having a discharge roller that performs
A plurality of transport rollers are disposed along the transport direction of the recording paper between the paper feed roller and the discharge roller including a print area by the ink head, and transport the recording paper,
A triangular prism-shaped side surface is disposed between the plurality of transport rollers so as to face the ink head, supports the transported recording paper together with the transport rollers, and sets a distance between the ink head and the recording paper. A plurality of support members so that is constant,
An ink-jet printer, comprising: suction means for sucking air from a gap between the transport roller and the support member and sucking recording paper toward the transport roller and the support member. 2. The ink jet printer according to claim 1, wherein said transport roller is driven to rotate by a rotation driving means of said discharge roller.

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