JP2003136798A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line type ink jet printer which can form a high quality image. SOLUTION: The ink jet printer comprises a plurality of ink heads, each having a plurality of ink nozzles for ejecting ink to a sheet arranged across the entire width of the sheet, arranged in the carrying direction of sheet, and a plurality of star rollers, i.e., sheet feed rollers, disposed between respective ink heads on the sheet discharge side in the carrying direction of sheet. Each star roller is located at a position touching such a part of the sheet as avoiding ink ejected from an ink jet head closer to the sheet feed side than the start roller, and the start roller closest to the sheet discharge side is located at a position touching a part of the sheet ejected with ink from an ink jet head closest to the sheet feed side. Trailing of undried ink due to the start roller is retarded and a high quality image can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line type ink jet printer capable of forming a high quality image.

[0002]

2. Description of the Related Art Conventionally, in an ink jet printer, an ink head provided with a plurality of ink nozzles for ejecting ink onto a sheet scans the sheet in a direction substantially orthogonal to the sheet conveying direction to eject the ink onto the sheet. 2. Description of the Related Art Serial-type inkjet printers that sequentially convey sheets to form images have become widespread. For serial type inkjet printers,
There are problems that the image forming speed is slow and that it is difficult to change the resolution.

In order to solve this problem, a line type ink jet printer having an ink head in which ink nozzles are arranged over the entire width of the paper in a direction substantially orthogonal to the paper conveyance direction has been developed. . Since the line type inkjet printer does not need to scan the ink head, the image forming speed is higher than that of the serial type. Further, in Japanese Unexamined Patent Publication No. 4-99688, a plurality of ink heads having a plurality of ink nozzles are arranged such that the positions of the ink nozzles respectively provided in the ink heads are offset from each other in a direction perpendicular to the paper transport direction, and There is disclosed a line-type inkjet printer provided side by side. In this inkjet printer, since the positions of the inks ejected from the ink nozzles of the respective ink heads are displaced from each other, it is possible to form an image with high resolution. In addition, the resolution can be changed by changing the number of ink heads used for image formation among the plurality of ink heads arranged in the paper transport direction.

[0004]

In an ink jet printer, at a position facing the ink head with the paper sandwiched,
A paper support member for supporting the paper being printed is provided, and further, a plurality of paper transfer rollers for transferring the paper while pressing the paper against the paper support member from the ink head toward the paper discharge side in the paper transfer direction. A star roller is provided. Since the star roller contacts the surface of the paper on which the image is formed and conveys the paper, the star roller may contact the undried ink and drag the ink onto the paper. Therefore, there is a problem in that the quality of an image formed with high resolution deteriorates. In addition, there is a problem that the paper that has absorbed ink swells during printing and the paper floats, and the floating paper comes into contact with the ink nozzles to deteriorate the image quality or damage the ink nozzles.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a roller for paper conveyance in a line type ink jet printer in which a plurality of ink heads are arranged in the paper conveyance direction. It is an object of the present invention to provide a line-type inkjet printer that can prevent deterioration of image quality by arranging the ink jet printer at a position that avoids undried ink.

Another object of the present invention is to:
The pressure for the paper transport roller to press the paper against the paper support member is changed in the paper transport direction, and the pressure on the paper discharge side roller for the paper transport direction is increased to increase the ink An object of the present invention is to provide a line-type inkjet printer that can prevent the sucked paper from floating.

Another object of the present invention is to:
A line that can prevent the floating of the paper during printing by changing the peripheral speed of the rollers for paper conveyance in the paper conveyance direction and making the peripheral speed of the rollers on the discharge side faster than the paper conveyance direction. Type inkjet printer.

[0008]

In an ink jet printer according to the present invention, an ink head provided with a plurality of ink nozzles for ejecting ink onto a sheet is arranged in a direction substantially orthogonal to the sheet conveying direction. In a line-type ink jet printer having a plurality of the ink heads arranged side by side, a plurality of rollers for conveying the paper are provided between the plurality of ink heads, and each roller is configured to eject the ink ejected onto the paper by the ink heads. It is characterized in that it is arranged at a position avoiding contact with the paper.

The ink jet printer according to the present invention is
Among the plurality of rollers, the plurality of rollers located closest to the paper feed side with respect to the paper transport direction are the ink heads located closest to the paper feed side with respect to the paper transport direction among the plurality of ink heads. It is characterized in that it is arranged at a position where it comes into contact with the intermediate portion of the portion of the paper on which the ink has been ejected.

The ink jet printer according to the present invention is
The plurality of ink heads are further provided with a plurality of rollers for carrying the paper near the paper discharge side with respect to the paper carrying direction, and each of the rollers has the most paper feeding direction among the plurality of ink heads in the paper carrying direction. It is characterized in that it is arranged at a position where it comes into contact with the portion of the paper on which ink has been ejected by the ink head located on the side.

The ink jet printer according to the present invention is
The plurality of ink heads are configured so that the position where ink is ejected to the paper can be changed by changing the position, and the positions of the plurality of ink heads that can print at the highest resolution The position of each roller is determined.

The ink jet printer according to the present invention is
A plurality of ink heads, each of which has a plurality of ink nozzles for ejecting ink onto the paper and are arranged substantially orthogonal to the paper conveyance direction, are arranged side by side in the paper conveyance direction. Further, ink is ejected by the ink heads. In a line-type inkjet printer including a paper support member that supports a paper, the paper conveyance is performed between the plurality of ink heads and closer to the paper ejection side than the plurality of ink heads in the paper conveyance direction. Each of the rollers is pressed against the paper supporting member by an elastic member, and the pressure applied to the paper supporting member varies depending on the position of each roller, and the pressure on the paper discharging side in the paper conveying direction is further increased. It is characterized in that the roller located nearer is pressed against the sheet supporting member with a larger pressure.

The ink jet printer according to the present invention is
The roller located closer to the sheet discharge side with respect to the sheet conveyance direction is characterized in that the elastic force of the elastic member is larger.

The ink jet printer according to the present invention is
Each roller is rotated by the drive source, and the peripheral speed of each roller differs depending on the position of each roller, so that the roller located closer to the paper discharge side in the paper conveyance direction has a higher peripheral speed. Characterize.

The ink jet printer according to the present invention is
The roller located closer to the paper discharge side with respect to the paper transport direction has a higher rotation speed.

The ink jet printer according to the present invention is
The roller located closer to the paper discharge side with respect to the paper transport direction has a larger diameter.

The ink jet printer according to the present invention is
Further, a rotating paper feeding roller is provided closer to the paper feeding side than the plurality of ink heads in the paper feeding direction, and the peripheral speed of the roller located closest to the paper feeding side in the paper feeding direction is the feeding speed. It is characterized by being higher than the peripheral speed of the paper roller.

The inkjet printer according to the present invention is
The peripheral speed of the roller located closest to the paper discharge side in the paper conveyance direction is 1.05 to 1.10 of the peripheral speed of the paper feed roller.
It is characterized by being doubled.

The ink jet printer according to the present invention is
The roller is a star roller.

In the present invention, a plurality of rollers for transporting a sheet using a star roller or the like are provided between a plurality of ink heads arranged in the sheet transport direction, and each roller is on the sheet feeding side rather than each roller. Since the ink is ejected from the ink head nearer to the position where it comes in contact with the paper while avoiding the ink ejected on the paper, it prevents the undried ink from being dragged by the paper transport roller and prevents the deterioration of the image quality. .

Further, in the present invention, a roller for transporting the paper is further provided closer to the paper discharge side than the plurality of ink heads, and the roller is adapted to eject the ink ejected by the ink head closest to the paper feed side. It is placed at the contact position.
Since there is no part for avoiding ink in the paper on which ink is ejected by all the ink heads, by arranging the roller at the position where it comes into contact with the ink that is ejected and dried most, This reduces the drag of the undried ink by the rollers of (1) to prevent the deterioration of the image quality.

Further, in the present invention, the position of the roller is determined so as to prevent the undried ink from being dragged with respect to the position of the ink head for obtaining the highest resolution, so that a high resolution and high quality image is obtained. Can be formed.

Further, in the present invention, the roller for conveying the sheet is pressed against the sheet supporting member by the elastic member, and the roller closer to the sheet discharging side in the sheet conveying direction is pressed with a stronger pressure. With this, the paper being printed is pressed against the paper support member by the roller, and the part of the paper that is more swelling and swelling is pressed against the paper support member more strongly to prevent the swelling of the swelling paper from sucking ink. To prevent deterioration of image quality and damage to ink nozzles.

Further, in the present invention, by increasing the peripheral speed of the roller located on the paper discharge side in the paper conveying direction, the tension of the paper being printed conveyed by the rotation of the roller is always maintained. To prevent the paper from floating and prevent deterioration of the image quality and damage to the ink nozzles. Further, since the peripheral speed is changed by changing the diameter of the roller, the structure is simple.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to the drawings showing the embodiments thereof. FIG. 1 is a perspective view showing the external appearance of the inkjet printer of the present invention. The paper is fed to the paper feed side, conveyed in the paper conveyance direction, printed by the internal printing unit, and ejected from the paper ejection side.

FIG. 2 is a plan view schematically showing a printing section inside the ink jet printer of the present invention, and FIG. 3 is a side view of the same. The ink jet printer of the present invention is a line type printer, and is provided with a plurality of ink nozzles for ejecting ink onto a sheet, which are arranged side by side over the entire width of the sheet in a direction substantially orthogonal to the sheet conveying direction. Head 11
Is equipped with. The first ink head 11 includes an ink tank (not shown), and the ink supplied from the ink tank is ejected from the ink nozzles to form an image on the paper. Further, the second ink head 12, the third ink head 13, and the fourth ink head 14 having the same structure and function are provided side by side in the paper transport direction.

In addition, between the first ink head 11 and the second ink head 12, a thin plate-shaped first roller which is a roller for transporting a sheet, the rotation axis of which is substantially perpendicular to the sheet transport direction.
The star rollers 21, 21, ... Are the same first drive shaft 31.
It is supported and provided by. Further, the second ink head 12 and the third ink head 1 serve as rollers for carrying the paper.
, 3 between the third ink head 13 and the fourth ink head 14, and the fourth ink head 1 and the third star roller 23, 23 ,.
The fourth star rollers 24, 24, ...
Are similarly supported and provided on the second drive shaft 32, the third drive shaft 33, and the fourth drive shaft 34. Further, a plate-shaped sheet supporting member P is provided so as to face the ink head, and each star roller is in contact with the sheet supporting member.
Further, a paper feed roller 4 for feeding the paper to the printing unit is provided near the paper feed side of the first ink head 11, and the paper fed by the paper feed roller 4 is applied to the paper support member P by each star roller. It is transported while being pressed.

FIG. 4 is a schematic view showing the structure of the first star roller 21, and FIG. 4 (a) is a front view and FIG. 4 (b) is a side view. The first star roller 21 is connected to the first drive shaft 3
1, the first drive shaft 31 is connected to a drive source (not shown) via a gear or the like, and is driven by the drive source to rotate the first star roller 21. First drive shaft 31
Penetrates the stay extending from the frame of the ink jet printer, and the stay restrains the movement in the paper transport direction. Further, elastic members 5, 5 are provided between the first drive shaft 31 and the frame on both sides of the first star roller 21.
The first drive shaft 31 is pressed against the paper supporting member P by the elastic force of the elastic members 5 and 5, and the first star roller 21 is also pressed against the paper supporting member P. Since the first drive shaft 31 is not constrained by the stay in the direction of the elastic force of the elastic members 5 and 5,
The sheet can be conveyed by being sandwiched between the star roller 21 and the sheet supporting member P. First star rollers 21,2
.. have the same structure, and are pressed against the sheet supporting member P by the elastic force of the elastic members 5, 5 ,.
Second star roller 22, 22, ..., Third star roller 2
, And the fourth star rollers 24, 24, ... Have the same structure, and are pressed against the sheet supporting member P by the elastic force of the elastic members 5, 5 ,.

The elastic force of the elastic members 5, 5, ..., which press the respective star rollers against the sheet supporting member P, is stronger toward the sheet discharge side, and each star roller has a stronger elastic force. The force applied to P is the first star rollers 21, 21, ... <Second star rollers 22,2.
2, ... <third star rollers 23, 23, ... <fourth star rollers 24, 24 ,. Ink is sequentially ejected from each ink head as the paper is conveyed, and the paper that has absorbed the ink further expands. Since the star roller closer to the paper discharge side is pressed more strongly to the paper support member P, the portion of the paper closer to the paper discharge side is pressed more strongly to the paper support member P. Since the more expanded paper is pressed against the paper support member P more strongly, it is possible to prevent the paper from floating, and prevent the deterioration of the image quality and the damage to the ink nozzle caused by the contact of the floating paper with the ink nozzles. it can.

Further, each of the star rollers is formed such that the diameter of the star roller closer to the sheet discharge side is larger, and the first star rollers 21, 21, ... <Second star roller 2
2, 22, ... <Third star rollers 23, 23, ... <Fourth
The diameter increases in the order of the star rollers 24, 24, .... When the respective star rollers are connected to the same drive source and rotated at the same rotational speed, the peripheral speed of each star roller differs depending on the diameter, and the first star rollers 21, 21 ,.
<Second Star Rollers 22, 22, ... <Third Star Rollers 23, 23, ... <Fourth Star Rollers 24, 24, ... The peripheral speed of the star roller is the speed that pulls the part of the paper that the star roller is in contact with, and the peripheral speed of the star roller that pulls the part of the paper that is closer to the paper discharge side is higher Receives the force of being pulled in the paper transport direction, and prevents the slack of the paper during printing. As a result, it is possible to prevent the deterioration of the image quality and the damage of the ink nozzles caused by the contact of the floating sheet due to the slack with the ink nozzles.

Further, the effect can be further enhanced by increasing the peripheral speed of the first star rollers 21, 21, ... If the difference in peripheral speed is too large, the paper may expand and the quality of the image may deteriorate. Therefore, the peripheral speed of the fourth star rollers 24, 24, ... Is 1.05 to the peripheral speed of the paper feed roller 4. It is desirable to be in the range of 1.10 times. The peripheral speed may be changed by changing the rotation speeds of the star rollers instead of changing the diameters of the star rollers. However, the structure becomes simpler when the peripheral speeds are changed depending on the difference in diameter.

FIG. 5 is a schematic diagram showing the ink ejection positions of the respective ink heads. The inkjet printer of the present invention can change the resolution by changing the relative position of the ink heads. Figure 5
When the respective ink heads are lined up with their ends aligned as shown in (a), the ink nozzles provided in the respective ink heads are aligned, and the ink ejected from the respective ink heads is the same on the paper. It is spit on the position. Figure 5
As shown in (b), when the positions of the third ink head 13 and the fourth ink head 14 are changed by a distance that is half the distance between the inks ejected from the ink nozzles, the third ink head 13 and the fourth ink head 13 When the ink ejected from the ink head 14 is ejected in the middle of the ink ejected by the first ink head 11 and the second ink head 12, the resolution of the image to be formed is shown in FIG. It can be doubled compared to. Further, as shown in FIG. 5C, when the positions of the respective ink heads are changed by displacing the distances of the ink ejected from the ink nozzles by ¼ of each other, the respective ink heads are ejected. The inks are displaced from each other and ejected onto the paper, and the resolution of the image to be formed can be quadrupled as compared with the case shown in FIG. Although FIG. 5 shows the inks with a space between them, the inks are actually ejected without any gap to form an image.

FIG. 6 is a schematic diagram showing the position of each star roller in association with the ink ejection position. As described above, the positions of the respective star rollers are determined in relation to the positions of the respective ink heads from which the inks ejected from the respective ink heads are displaced from each other and ejected so that the highest resolution can be obtained. . First, the first star rollers 21 and 2
As shown in FIG. 6A, 1, ... Are located at positions where the first ink head 11 contacts the intermediate portion of the paper portion on which the ink is ejected, as shown in FIG. 6A. It is equipped. In addition, the second star roller 22,
As shown in FIG. 6B, reference numerals 22, ... Are intermediate portions of the sheet on which the ink is ejected by the first ink head 11 and the second ink head 12, which are portions of the sheet on which the ink is not ejected. It is provided at a position where it contacts the part. Similarly, the third star rollers 23, 23, ...
It is provided at a position where it comes into contact with the intermediate portion of the portion of the paper on which the ink is ejected by the ink head 11, the second ink head 12, and the third ink head 13. The first star rollers 21, 21, ..., The second star rollers 22, 22 ,.
, And the third star rollers 23, 23, ... Contact the paper to avoid the ink ejected on the paper and convey the paper by rotation, so that the star roller does not come into contact with the ink during the conveyance, It is possible to prevent the image quality from being degraded by the roller dragging the ink.

Further, as shown in FIG. 6 (d), the fourth star rollers 24, 24, ... Are provided at positions in contact with the portion of the paper on which the ink is ejected by the first ink head 11. . Since there is no portion of the paper on which ink is not ejected, the fourth star rollers 24, 24, ...
The ink is first ejected by the ink head 11 and comes into contact with the ink that is likely to be already dried, and the paper is conveyed by rotation. As a result, it is possible to reduce drag of the undried ink by the star roller and prevent deterioration of image quality.

As described in detail above, in the line type ink jet printer of the present invention, it is possible to prevent the deterioration of the image quality due to the undried ink being dragged by the roller for transporting the paper, which uses the star roller, and to prevent the ink from being discharged. High-resolution and high-quality images can be formed because it is possible to prevent image quality deterioration and ink nozzle damage that occur when suctioned and swelled paper and loose paper during transport contact the ink nozzles. can do.

In the present embodiment, the paper carrying roller is the star roller, but a roller having another shape such as a spur roller may be used as the paper carrying roller. Further, in the present embodiment, the resolution can be changed by moving the respective ink heads, but a fixed ink head may be provided.

[0037]

According to the present invention, a roller for transporting a sheet using a star roller or the like is provided between a plurality of ink heads lined up in the sheet transport direction, and each roller is on the sheet feeding side rather than each roller. Since the ink is ejected from the ink head nearer to the position where it comes in contact with the paper while avoiding the ink ejected on the paper, it prevents the undried ink from being dragged by the paper transport roller and prevents the deterioration of the image quality. .

Further, in the present invention, a roller for transporting the paper is further provided closer to the paper discharge side than the plurality of ink heads, and the roller is adapted to eject the ink ejected by the ink head closest to the paper feed side. It is placed at the contact position.
By arranging the roller for transporting the sheet at a position where it comes into contact with the ink that is first ejected and dried most, the drag of the undried ink by the roller is reduced and the deterioration of the image quality is prevented.

Further, in the present invention, since the position of the roller is determined so as to prevent the undried ink from being dragged with respect to the position of the ink head for obtaining the highest resolution, a high resolution and high quality image is obtained. Can be formed.

Further, in the present invention, the roller for conveying the sheet is pressed against the sheet supporting member by the elastic member, and the roller closer to the discharge side in the sheet conveying direction is pressed with a stronger pressure. By doing so, the part of the paper that swells more and absorbs ink is pressed against the paper support member more strongly, and the swelling of the paper that absorbs ink is prevented from floating, thus lowering the image quality and damaging the ink nozzles. To prevent.

Further, in the present invention, by increasing the peripheral speed of the roller located on the paper discharge side in the paper conveying direction, the tension of the paper being printed conveyed by the rotation of the roller is always maintained. To prevent the paper from floating and prevent deterioration of the image quality and damage to the ink nozzles. Further, since the peripheral speed is changed by changing the diameter of the roller, the present invention has excellent effects such as a simple structure.

[Brief description of drawings]

FIG. 1 is a perspective view showing the external appearance of an inkjet printer of the present invention.

FIG. 2 is a plan view schematically showing a printing unit inside the inkjet printer of the present invention.

FIG. 3 is a side view schematically showing a printing unit inside the inkjet printer of the present invention.

FIG. 4 is a schematic view showing a structure of a first star roller.

FIG. 5 is a schematic diagram showing ink ejection positions of respective ink heads.

FIG. 6 is a schematic diagram showing the position of each star roller in association with the ink ejection position.

[Explanation of symbols]

11-14 First to fourth ink heads 21-24 First to fourth star rollers 4 paper feed rollers 5 Elastic member P paper support member

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B65H 5/06 B65H 5/06 N B41J 3/04 101Z F term (reference) 2C056 EA16 FA13 HA29 HA33 HA34 2C059 CC03 CC21 3F049 CA03 CA33 DA14 EA13 LA07 LB03

Claims (12)

[Claims] 1. A line type ink jet printer comprising a plurality of ink heads, each of which is provided with a plurality of ink nozzles for ejecting ink onto a sheet arranged in a direction substantially orthogonal to the sheet conveying direction, arranged in the sheet conveying direction. A plurality of rollers for transporting a sheet are provided between the plurality of ink heads, and each roller is arranged at a position where it comes into contact with the sheet while avoiding ink ejected onto the sheet by the ink head. An inkjet printer characterized in that 2. Among the plurality of rollers, the plurality of rollers located closest to the paper feed side with respect to the paper transport direction are the rollers closest to the paper feed side with respect to the paper transport direction of the plurality of ink heads. The ink jet printer according to claim 1, wherein the ink jet printer is arranged at a position where it comes into contact with an intermediate portion of a portion of the paper on which ink is ejected by the ink head located. 3. A plurality of rollers for transporting a sheet are further provided toward the paper discharge side with respect to the sheet transport direction of the plurality of ink heads, and each of the rollers is disposed in the sheet transport direction of the plurality of ink heads. 3. The ink jet printer according to claim 1, wherein the ink jet printer is arranged at a position where it comes into contact with a portion of the paper on which ink is ejected by the ink head located closest to the paper feed side. 4. The plurality of ink heads are configured so that the positions at which ink is ejected onto the paper can be changed by changing the positions, and the plurality of ink heads capable of printing at the highest resolution. 2. The position of each roller is defined with respect to the position of.
4. The inkjet printer according to any one of 3 to 3. 5. A plurality of ink heads, each of which has a plurality of ink nozzles for ejecting ink onto a sheet and are arranged in a direction substantially orthogonal to the sheet conveying direction, are arranged side by side in the sheet conveying direction. In a line-type inkjet printer including a paper support member that supports a paper on which ink is ejected, a paper discharge side in the paper transport direction with respect to each of the plurality of ink heads and the plurality of ink heads. To the side
It is equipped with multiple rollers for paper transport, and each roller is pressed against the paper support member by an elastic member.The pressure applied to the paper support member varies depending on the position of each roller, and is more ejected in the paper transport direction. An ink jet printer characterized in that a roller located closer to the paper is pressed against the paper support member with a larger pressure. 6. The ink jet printer according to claim 5, wherein the roller located closer to the paper discharge side with respect to the paper transport direction has a larger elastic force of the elastic member. 7. Each roller is rotated by a drive source, and the peripheral speed of each roller is different depending on the position of each roller, and the roller located closer to the paper discharge side in the paper conveyance direction has a peripheral speed. The ink jet printer according to claim 5 or 6, characterized in that 8. The ink jet printer according to claim 7, wherein the roller positioned closer to the paper discharge side with respect to the paper transport direction has a higher rotation speed. 9. The ink jet printer according to claim 7, wherein the roller located closer to the paper discharge side with respect to the paper transport direction has a larger diameter. 10. A circumference of a roller located closest to the paper feed side in the paper transport direction, further comprising a paper feed roller that rotates closer to the paper feed side than the plurality of ink heads in the paper transport direction. The inkjet printer according to claim 7, wherein the speed is higher than the peripheral speed of the paper feed roller. 11. The peripheral speed of the roller located closest to the paper discharge side in the paper transport direction is 1.05 to 1.10 times the peripheral speed of the paper feed roller. 1
The inkjet printer described in 0. 12. The ink jet printer according to claim 1, wherein the roller is a star roller.