JPH1058659A - Ink jet head assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve resolution of printing by using a relatively simple assembly constitution. SOLUTION: The ink jet head assembly comprises an ink jet head having an injection nozzle surface having a plurality of injection ports 11a for injecting ink to inject the ink from the ports 11a to a printing surface 12a of a recording sheet 12 fed in a sheet feeding direction, a carriage movable in a main scanning direction perpendicular to the sheet feeding direction while holding the head, a drive motor for moving the carriage in the main scanning direction, and a driver for moving the head to longitudinally move an ink injecting surface to the surface 12a at a predetermined distance. In this case, the injecting direction of the head is inclined at a predetermined angle along the sheet feeding direction to the surface 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of an ink jet head device used for an ink jet type printer or the like.

[0002]

2. Description of the Related Art Conventionally, ink jet printers include:
An ink jet head provided with a plurality of ejection ports moves (main scan) along the platen to print on the recording paper one pass at a time, and further rotates the platen at the end of one pass printing to record. 2. Description of the Related Art An ink jet head device of a type in which a sheet is moved in a paper feed direction (sub-scan) and the next main scan is sequentially performed. A printer including such an ink jet head device has a relatively simple device configuration, and is excellent in terms of manufacturing cost, running cost, and the like.

[0003]

However, according to the above-described conventional ink jet printer using the ink jet head device, the resolution is inferior to that of the laser beam printer or the like.

[0004] Therefore, it is desired to improve the printing resolution also in the ink jet head device. For this purpose, the pitch of the ejection ports provided in the head is reduced, or the ejection ports are formed in a staggered pattern. Multiple columns,
It is necessary to perform the paper feeding with high accuracy, and the configuration of the apparatus becomes complicated and sophisticated, which also leads to an increase in essential manufacturing costs and running costs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an ink jet head device having a relatively simple device configuration and capable of improving printing resolution.

[0006]

According to a first aspect of the present invention, there is provided an ink jet head device having an ink jetting surface provided with a plurality of jetting ports for jetting ink, wherein the ink jetting device is provided in a paper feeding direction. An inkjet head that ejects ink from the ejection ports onto a surface of a sheet to be fed, a carriage that can move in a main scanning direction orthogonal to the paper feeding direction while holding the inkjet head, and moves the carriage in the main scanning direction. Main scanning means for moving, and forward and backward moving means for moving the ink jet head so that the ink jetting surface moves back and forth by a predetermined distance with respect to the surface of the paper, and the jetting direction of the ink jet head is It is characterized by being inclined by a predetermined angle along the paper feeding direction with respect to the surface of the paper.

According to the first aspect of the present invention, the carriage is moved in the main scanning direction by the main scanning means, whereby the ink jet head held by the carriage is moved in the main scanning direction. In parallel with this movement, ink is ejected from a plurality of ejection ports provided on the ink ejection surface to the surface of the sheet by the inkjet head, and main scanning (that is, printing for one pass) is performed. In the case of a normal inkjet head device, the paper is moved in the paper feed direction by one pass at this point (sub-scan).
After that, the next main scan is performed.
When the (n: natural number) main scanning is completed, the (n + 1) th main scanning is performed after the ink ejecting surface is moved by a predetermined distance before or after the sheet surface by the front / rear moving means. Here, since the ejection direction of the inkjet head is inclined by a predetermined angle along the paper feeding direction with respect to the surface of the sheet, the sheet is interposed between the n-th main scanning and the (n + 1) -th main scanning. Even if it does not move in the paper feed direction,
In contrast to the first main scan, the (n + 1) th main scan can be advanced on the paper in the paper feed direction by a length corresponding to the predetermined angle. That is, by moving the ink jetting surface back and forth by the back and forth moving means, the same operation as that of paper feeding can be obtained without paper feeding (sub-scanning).

According to a second aspect of the present invention, there is provided an ink jet head device having an ink ejection surface in which a plurality of ejection ports for ejecting ink are arranged along a predetermined direction, and the ink ejection surface is orthogonal to the predetermined direction. A line head type inkjet head for ejecting ink from the ejection port to a surface of a sheet fed in a paper feed direction; and the inkjet so that the ink ejection surface moves a predetermined distance back and forth with respect to the surface of the sheet. And a back-and-forth moving means for moving the head, wherein the jetting direction of the ink jet head is inclined at a predetermined angle with respect to the surface of the paper along the paper feeding direction.

According to the second aspect of the present invention, the ink is ejected onto the surface of the paper from the plurality of ejection ports arranged in a predetermined direction on the ink ejection surface by the line head type inkjet head. Then, line printing for one line along the predetermined direction is performed. In the case of a normal line head type ink jet head device, at this point, the paper is moved by one line in the paper feed direction, and then the next line printing is performed. In the case of the present invention, the n-th (n : Natural number) After finishing the second line printing,
After the ink ejecting surface is moved by a predetermined distance before or after the surface of the sheet by the front-rear moving means, the (n + 1) th line printing is performed. Here, since the ejection direction of the inkjet head is inclined by a predetermined angle along the paper feed direction with respect to the surface of the paper, the paper is ejected between the n-th line printing and the (n + 1) -th line printing. Even without moving in the feed direction, the (n + 1) th line print can be advanced on the paper by the length corresponding to the predetermined angle in the paper feed direction with respect to the n-th line print. That is, by moving the ink jetting surface back and forth by the front and rear moving means, the same operation as the paper feeding can be obtained without paper feeding.

According to a third aspect of the present invention, in the ink jet head device according to the first or second aspect, the plurality of ejection ports are inclined with respect to the ink ejection surface along the paper feeding direction. It is characterized by being provided.

According to the third aspect of the present invention, since the plurality of ejection ports are provided to be inclined with respect to the ink ejection surface in the paper feeding direction, the n-th and n + 1-th ejection ports are provided. Even if the paper is not moved in the paper feed direction during the period, the (n + 1) th main scan or line print can be advanced on the paper in the paper feed direction with respect to the nth main scan or line print.

According to a fourth aspect of the present invention, in the inkjet head device according to the first aspect, the carriage holds the inkjet head at an angle in the paper feeding direction. .

According to the ink jet head device of the fourth aspect, the carriage holds the ink jet head inclined in the paper feed direction, so that the n-th and n-th ink jet heads can be held.
Even if the paper is not moved in the paper feed direction between the + 1st and the + 1st, the (n + 1) th main scan can be advanced on the paper in the paper feed direction with respect to the nth main scan.

According to a fifth aspect of the present invention, in the ink jet head device according to the first or fourth aspect, the forward / backward moving means controls the ink jet head each time the main scanning means performs a main scan once. Each time the main scanning unit performs main scanning a predetermined number of times,
The paper is fed in the paper feed direction.

According to the ink jet head device of the fifth aspect, when the n-th main scanning is completed by the main scanning means, the ink ejecting surface is moved forward or rearward with respect to the surface of the sheet by the front-rear moving means. Moved by a predetermined distance, and
The first main scan is performed. When the (n + 1) th main scanning is completed by the main scanning unit, the ink ejection surface is moved forward or backward by a predetermined distance with respect to the surface of the sheet by the front / rear moving unit, and the (n + 2) th main scanning is performed. Will be As described above, the main scanning is performed m times by moving the ink ejecting surface back and forth by the back and forth moving means by m (m: natural number) times without feeding the paper. When the m main scans have been completed, the paper is fed in the paper feed direction by the back and forth moving means, and the next main scan is continued.

According to a sixth aspect of the present invention, in the ink jet head device of the first, fourth or fifth aspect, the front-rear moving means is separated from the ink jetting surface and has a predetermined position along the main scanning direction. The ink jet head is moved back and forth by rotating the ink jet head about the eccentric axis of (i).

According to the ink jet head device of the sixth aspect, when the n-th main scanning is completed, the ink jet head is rotated around a predetermined eccentric axis by the back and forth moving means, and the ink jetting surface is moved back and forth. Moved to Thereafter, the (n + 1) th main scan is performed.

According to a seventh aspect of the present invention, in the ink jet head device according to any one of the first to sixth aspects, the plurality of ejection ports have a predetermined dot pitch in the paper feed direction. A plurality of arrays are arranged at a predetermined head pitch along the paper feed direction so that an array can be simultaneously formed on the surface of the paper, and between dot pitches formed on the surface of the paper before one back and forth movement. The predetermined distance and the predetermined angle are defined so that a dot is formed after the one forward-backward movement.

According to the ink jet head device of the seventh aspect, in the n-th main scan, a plurality of ejection ports arranged at a predetermined head pitch along the paper feed direction are used to form a sheet in the paper feed direction. A dot array having a predetermined dot pitch is simultaneously formed on the surface of the sheet. And this n-th
After the end of the main scanning, the ink jetting surface is moved forward or backward by a predetermined distance with respect to the surface of the sheet by the front-rear moving means. Next, in the (n + 1) th main scan, the nth
The dot array is formed on the surface of the sheet so that dots are formed between the dot pitches formed on the surface of the sheet in the second main scan.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a schematic configuration of an ink jet printer 1 according to the present embodiment.
As shown in FIG. 1, an inkjet printer 1 according to the present embodiment includes a cylindrical platen 2 extending in an axial direction.
The platen 2 is attached to the frame 3 via a shaft (not shown) so as to be rotatable in the arrow H direction.

The ink jet head 4 is mounted on a carriage 5 so as to face the platen 2, and the carriage 5 is slidably supported by a guide rod 6 provided parallel to the axis of the platen 2. With a pair of pulleys 7,
8 is engaged with a timing belt 9 wound around the belt. Therefore, one pulley 7 is used for the carriage drive motor 1.
0, the carriage 5 is moved in the direction of arrow K along the platen 2 by feeding the timing belt 9. Thus, in the present embodiment, the pulley 7
And 8, the timing belt 9 and the drive motor 10 constitute an example of a main scanning unit.

The ink ejecting head 4 reciprocated within a predetermined printing range at the time of printing by such a mechanism has a plurality of ink flow paths and a plurality of ink flow paths provided corresponding to the ink flow paths. Spray nozzle 11 with spout
It has.

Here, the configuration of the ink jet head 4 will be described in detail with reference to FIGS. FIG. 2 is a cross-sectional view of the ink jet head 4 as viewed from the axial direction of the guide rod 6, and FIGS. 3 and 4 are enlarged cross-sectional views of a portion surrounded by C in FIG. 3 shows the state of the ejection and the ink droplets in the first pass, and FIG. 4 shows the state of the ejection and the ink droplets in the subsequent second pass.

In FIG. 2, the ink flow path of the ejection nozzle 11 is fixed to the frame 3 or
Ink is supplied from an ink supply device mounted on the printer, and when a diaphragm forming a wall of the ink flow path is deformed by a drive circuit (not shown) based on a command from a control device (not shown). The ink is ejected from the ejection port of the ejection nozzle 11 toward the printing surface 12a of the recording paper 12 by a pressure change caused by the deformation. Carriage 5
The main scanning is performed by ejecting ink in accordance with the movement of the paper, that is, an image is formed for each pass, and each time the image formation for each pass is completed, the paper 12 is fed in the paper feed direction (sub-scan). It is configured to:

As shown in FIG. 3 and FIG. 4 in an enlarged manner, the ejection direction of the plurality of ejection ports 11 a of the ejection nozzle 11 is in a paper feed direction indicated by an arrow T with respect to the printing surface 12 a of the recording paper 12. Is tilted by a predetermined angle. The plurality of ejection ports 11a are arranged at a predetermined head pitch along the paper feed direction so that a dot array having a predetermined dot pitch in the paper feed direction can be simultaneously formed on the printing surface 12a. When the head gap is small as shown in FIG.
The ink droplet 101 formed in the first pass is formed on the printing surface 12 and then the ink formed in the second pass after the ejection nozzle surface moves backward as shown in FIG. 4, that is, when the head gap is increased. The moving distance of the ejection nozzle surface to the printing surface 12a and the inclination angle of the ejection direction are such that the droplets 102 are located between the ink droplets 101 formed in the first pass, respectively.
Stipulated. Such a moving distance and an inclination angle are:
It may be obtained experimentally, may be obtained by computer simulation, or may be obtained by manual calculation or chart.

Referring again to FIG. 1, one end of the guide rod 6 is rotatably attached to the frame 3 by a bearing 6a. At the other end, a pulley 30 for rotating the guide rod 6 and this pulley Drive device 4 for driving 30
0 is provided. The pulley 30 is attached to the frame 3 so as to be rotatable in the direction of arrow E. Pulley 30
Is driven by the driving device 40, the guide rod 6 rotates, whereby the angle of the carriage 5 changes, and the distance from the ejection nozzle surface of the ink ejection head 4 to the platen 2 (that is, the printing surface 12a). Are configured to change by a predetermined distance. As described above, in the present embodiment, an example of the back-and-forth moving unit is configured by the guide rod 6, the pulley 30, and the driving device 40.

In this case, as shown in FIG. 5, if the guide rod 6 is mounted on an eccentric shaft eccentric from the rotation center shaft 30a of the pulley 30, the pulley 30
0, the guide roller 6 has an arrow F
By the movement described above, the ejection nozzle surface can be moved back and forth with respect to the printing surface 12a.

As shown in FIG. 6, a linear moving pulse motor 51 is provided on the carriage 5, and the ink jet head 4 is mounted on a slide table 52 which is moved forward and backward by the motor. Alternatively, as shown in FIG. 7, a stepping motor 53
And the ink jet head 4 may be placed on the slide table 54 which is moved forward and backward by this. The mechanism for moving the ink jet head 4 back and forth with respect to the printing surface 12a can be configured by applying various known techniques.

In FIG. 1, the recording paper 12 is supplied in a direction indicated by an arrow L from a paper supply opening (not shown) behind the frame 3, is sent in a direction indicated by an arrow M by rotation of the platen 2, and is discharged from a paper discharge opening (not shown). Is done.

When the recording operation is completed, the ink jet head 4
Is retracted to a non-recording position, and a recovery device 13 is provided at a position facing the ink jet head 4 in the non-recording position. The recovery device 13 is provided on a side of the platen 2 and has a cap member 14 made of rubber. The cap member 14 has a rectangular recess corresponding to the injection nozzle 11. When the carriage 5 moves to the position of the recovery device 13 when the printing operation is stopped, the cam 15 and the drive thereof are driven. The cap member 14 is moved in the P direction by using a mechanism, and is fitted to the ejection nozzle 11 of the ink ejection head 4 in a liquid-tight state.

The concave portion of the cap member 14 is connected via a tube to a pump 16 operated by a cam 15, so that the thickened ink in the ink jet head 4 is in the fitted state as described above. The suctioned ink is sucked through the concave portion of the member 14, and the sucked ink is discharged to the outlet 16a.
From the waste liquid form 18.

A wiper device is provided adjacent to the recovery device 13. The wiper blade 19 made of rubber is moved forward or backward in the N direction in accordance with the rotation of the cam 15, and is sucked as described above. It has the function of wiping the ink remaining on the tip end surface of the later ejection nozzle 11.

The operation of the ink jet head 4 of the present embodiment as described above will be described with reference to FIGS. As shown in FIG. 3, first, the recording paper 12 is fed and positioned at a position where the first pass is to be printed. Then, pulley 7
And 8, the timing belt 9 and the drive motor 10 move the carriage 5 in the main scanning direction (the direction perpendicular to the plane of FIG. 3), and thereby move the ink jet head 4 held by the carriage 5 in the main scanning direction. Is done. In parallel with this movement, ink is ejected from the plurality of ejection ports 11a provided on the ejection nozzle surface by the ejection nozzle 11 onto the printing surface 12a, and main scanning (that is, printing for one pass) is performed. When the n-th (n: natural number) main scanning is completed, the guide roller 6, the pulley 30, and the driving device 40 move the ejection nozzle surface behind the printing surface 12a by a predetermined distance. As shown in (1), the (n + 1) th main scan is performed. Here, since the ejection direction of the ejection nozzle 11 is inclined by a predetermined angle along the paper feed direction with respect to the printing surface 12a, the ejection direction is between the plurality of ink droplets 101 formed by the n-th main scan. The plurality of ink droplets 102 are respectively formed by the (n + 1) th main scan. That is, even if the recording paper 12 is not moved in the paper feed direction, the (n + 1) -th main scan is performed on the printing surface 12 by a length corresponding to a predetermined angle at which the ejection is inclined with respect to the n-th main scan.
a in the paper feed direction.

As described above, according to the present embodiment, by moving the ejection nozzle 11 back and forth with respect to the printing surface 12a, the same operation as when the recording paper 12 is fed without paper feeding is performed. Can be obtained. Therefore, even if the pitch of the ejection ports 11a of the ejection nozzles 11 is relatively large, a dot pitch corresponding to an ejection port pitch that is equal to or less than half of the ejection port pitch can be obtained on the printing surface 12a.

In this embodiment, as shown in FIGS. 3 and 4, the plurality of ejection ports 11a are provided to be inclined with respect to the ejection nozzle surface along the paper feed direction. The ejection head 4 may be configured to be inclined and held along the paper feeding direction. With this configuration,
Even if the recording paper 12 is not moved in the paper feed direction between the nth and n + 1th times, the (n + 1) th main scan is performed on the printing surface 12a in the paper feed direction with respect to the nth main scan. You can proceed to.

In this embodiment, the recording paper 12 is fed each time two main scans are performed (ie, FIG. 4).
In this case, the ink droplets 102 formed in the second pass are replaced with the ink droplets 10 formed in the paper feeding direction formed in the first pass.
, But the recording paper 12 is fed every three or more main scans (that is, the ink droplets formed in the second pass, the third pass,. Between the ink droplets formed in the eyes). Even with such a configuration, the main scanning can be performed m times by moving the ink ejecting surface back and forth by the back and forth moving means by m (m: natural number) times without paper feeding. At the end of the main scan,
What is necessary is just to feed the recording paper 12 in the paper feed direction and shift to the next main scanning.

Further, in the present embodiment, the injection port 11a
Although FIG. 3 and FIG. 4 are tilted downward, they may be tilted upward. In this case, the injection surface may be moved forward after one pass.

In the above-described embodiment, the case where the present invention is applied to a mono-color ink jet head device having a jet head having only one row of jet nozzles has been described. However, the present invention is not limited to this. Instead, the present invention is also applicable to a color inkjet head device having a plurality of ejection nozzle rows. In this case, a plurality of ink jet heads may be mounted on the carriage 5 moved by the front-rear moving means in a state of being arranged along the platen 2. In this case, the recovery device 13 may be provided with a cap member having the above-described suction function as many as the number of the ejection nozzles, or may be provided with one cap member having the suction function and replace each ejection nozzle with this cap member. , The suction operation may be performed, and a plurality of cap members having no suction function for preventing the ejection nozzle from drying or the like may be prepared according to the number of ejection nozzles.

Further, in the above-described embodiment, instead of the scanning type ink jet head 4 for main scanning by the carriage 5, an ink jetting surface on which a plurality of jetting ports for jetting ink are arranged along the main scanning direction. May be adopted. In this case, FIG.
The ejecting nozzle surface is moved back and forth by a predetermined distance with respect to the printing surface of the recording paper by means of forward and backward moving means such as the guide rod 6, the pulley 30, and the driving device 40. What is necessary is just to comprise so that it may incline by the predetermined angle along the paper feed direction with respect to the printing surface of a recording paper. With this configuration, as in the case of the above-described embodiment, by moving the ejection nozzle surface back and forth by the front and rear moving means, the same operation as that of paper feeding can be obtained without paper feeding. Can be.

[0040]

As described in detail above, according to the ink jet head device of the first aspect, the ink ejecting surface is moved forward or backward by a predetermined distance with respect to the surface of the paper by the back and forth moving means, Since the ejection direction of the inkjet head is inclined by a predetermined angle with respect to the surface of the paper along the paper feed direction, the paper is fed in the paper feed direction between the nth main scan and the (n + 1) th main scan. , The (n + 1) th main scan can be advanced in the paper feed direction by a length corresponding to the predetermined angle on the paper, compared to the nth main scan. However, even if the pitch of the ejection ports is relatively large, it is possible to obtain high-resolution printing quality in the paper feeding direction.

According to the ink jet head device of the present invention, the ink jetting surface is moved by a predetermined distance before or after the sheet surface by the back and forth moving means by the line head type ink jet head. Is inclined at a predetermined angle along the paper feed direction with respect to the surface of the paper, so that the paper is moved in the paper feed direction between the n-th line printing and the (n + 1) -th line printing. Even if the line printing is not performed, the (n + 1) th line printing can be advanced in the paper feeding direction on the paper by a length corresponding to the predetermined angle with respect to the nth line printing. Even if the pitch is relatively large, it is possible to obtain high-quality print quality in the paper feeding direction.

According to the third aspect of the present invention, since the plurality of ejection ports are provided to be inclined with respect to the ink ejection surface in the paper feeding direction, the pitch of the ejection ports in the paper feeding direction is provided. Is relatively large, it is possible to obtain high-resolution print quality in the paper feeding direction.

According to the ink jet head device of the fourth aspect, the carriage holds the ink jet head at an angle in the paper feeding direction, so that even if the pitch of the ejection ports in the paper feeding direction is relatively large, the carriage can hold the ink jet head. It is possible to obtain high-quality print quality in the feed direction.

According to the fifth aspect of the present invention, the pitch of the ejection ports is relatively small in the paper feeding direction by moving the ink jetting surface back and forth by the front / rear moving means only m times without feeding the paper. Even if it is large, it is possible to obtain a printing quality with a resolution of about m times the pitch of the ejection port in the paper feeding direction.

According to the ink jet head device of the present invention, the ink jetting surface can be moved back and forth by the back and forth moving means having a relatively simple structure, and high resolution printing quality can be obtained.

According to the ink jet head device of the present invention, a plurality of ejection ports arranged at a predetermined head pitch form a dot array of a predetermined dot pitch in the paper feed direction, and provide a high resolution. Printing quality can be obtained.

As a result, according to the present invention, an ink jet head device capable of obtaining high-resolution print quality using a relatively simple device configuration even if the pitch of the ejection ports on the ink ejection surface is relatively large. realizable.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of an ink jet printer according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an ink jet head in the ink jet printer of FIG.

FIG. 3 is an enlarged cross-sectional view of a portion surrounded by C in FIG. 2, showing a state of ejection and ink droplets in a first pass.

FIG. 4 is an enlarged cross-sectional view of a portion surrounded by C in FIG. 2, showing a state of ejection and ink droplets in a second pass.

FIG. 5 is a conceptual diagram showing a state in which a guide roller moves back and forth in the ink jet printer of FIG.

FIG. 6 is a side view of an ink jet head device showing another embodiment for moving an ink jet head back and forth.

FIG. 7 is a side view of an ink jet head device showing still another embodiment for moving an ink jet head back and forth.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ink-jet printer 2 ... Platen 3 ... Frame 4 ... Ink ejection head 5 ... Carriage 6 ... Guide rod 7 ... Pulley 8 ... Pulley 9 ... Timing belt 10 ... Drive motor 11 ... Injection nozzle 11a ... Injection port 12 ... Recording paper 12a ... Printing surface 13 ... Recovery device 14 ... Cap member 15 ... Cam 16 ... Pump 17 ... Tube 18 ... Waste liquid foam 19 ... Wiper blade 30 ... Pulley 40 ... Drive device 51 ... Linear moving pulse motor 52 ... Slide plate 53 ... Stepping motor 54 ... Slide plate 101 ... Ink drop 102 ... Ink drop

Claims (7)

[Claims] 1. An ink jet head having an ink jetting surface provided with a plurality of jetting ports for jetting ink, jetting ink from the jetting port onto a surface of a sheet fed in a paper feed direction, and A carriage movable in a main scanning direction orthogonal to the paper feeding direction while holding the main scanning means; a main scanning means for moving the carriage in the main scanning direction; Forward and backward moving means for moving the inkjet head so as to move by a distance, wherein the ejection direction of the inkjet head is inclined by a predetermined angle with respect to the surface of the paper along the paper feeding direction. An inkjet head device characterized by the above-mentioned. 2. A plurality of ejection ports for ejecting ink have an ink ejection surface arranged along a predetermined direction, and the ink is ejected from the ejection ports onto a surface of a sheet fed in a paper feed direction orthogonal to the predetermined direction. A line head type ink jet head for jetting the ink jet head, and a front / rear moving means for moving the ink jet head so that the ink jetting surface moves back and forth by a predetermined distance with respect to the surface of the paper, The ink jet head device is characterized in that the ejection direction is inclined at a predetermined angle with respect to the surface of the paper along the paper feeding direction. 3. The ink jet head device according to claim 1, wherein the plurality of ejection ports are provided so as to be inclined with respect to the ink ejection surface along the paper feeding direction. 4. The ink jet head device according to claim 1, wherein the carriage holds the ink jet head inclined along the paper feeding direction. 5. The back-and-forth moving means moves the ink-jet head each time the main scanning means performs main scanning once, and every time the main scanning means performs main scanning a predetermined number of times, the paper is moved. The ink jet head device according to claim 1, wherein the ink is fed in the paper feeding direction. 6. The forward / backward moving means moves the ink jetting surface back and forth by rotating the ink jet head around a predetermined eccentric axis along the main scanning direction, which is off the ink jetting surface. The ink jet head device according to claim 1, 4 or 5, wherein 7. The plurality of ejection ports are arranged at a predetermined head pitch along the paper feeding direction so that a dot array having a predetermined dot pitch in the paper feeding direction can be simultaneously formed on the surface of the paper. The predetermined distance and the predetermined angle are defined so that dots are formed after the one front-back movement between dot pitches formed on the surface of the sheet before one front-back movement. The inkjet head device according to any one of claims 1 to 6, wherein: