JP2002292859A - Recording head and ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording head elongated by arranging a plurality of heads in which the nozzle pitch error of seam can be minimized even if respective heads are not aligned with high accuracy, and an ink jet printer utilizing that recording head. SOLUTION: In a recording head comprising a plurality of basic heads each having a plurality of recording elements arranged in one direction, the basic head has one or more recording element arranged at a pitch narrower than a prescribed pitch at the end part thereof. Adjacent basic elements are disposed at different positions in the direction orthogonal to the arranging direction where the recording element arrays are not spaced apart more than the prescribed pitch. Furthermore, each basic head drives only such recording elements as the interval does not exceed the prescribed pitch at the end part where adjacent basic heads are present and are selected to approximate the prescribed pitch most.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of recording heads used for various printers, and more particularly, to a recording head formed by arranging a plurality of recording heads (basic heads) to be long. The present invention relates to a recording head capable of recording a high-quality image and having good productivity and utilization efficiency of each basic head, and an ink jet printer using the recording head.

[0002]

2. Description of the Related Art Various types of printers employ a thermal ink jet system in which a portion of ink is rapidly vaporized by heating with a heater, and ink droplets are ejected from nozzles by the expansion force or the like (Japanese Patent Laid-Open No. 48-48). No. 9622, 5
No. 4-51837). Also, static electricity,
There is also known a printer using an ink jet in which a vibration plate is vibrated by driving means such as a piezo element and the like, and ink droplets are ejected from nozzles by the energy of the vibration plate (Japanese Patent Laid-Open Publication No. Hei 1 (1994)).
Nos. 1-207956 and 11-309850, etc.).

[0003] Various printers using a so-called print head, such as an ink jet printer, a thermal printer and a dot impact printer, use a small print head having a short array of print elements and use a print medium such as an image receiving paper. A so-called serial type printer which performs image recording by combining intermittent conveyance with scanning of a recording head in which a large number of recording elements are arranged is mainly used.

[0004] On the other hand, there is also known a printer using a so-called line head in which recording elements are arranged corresponding to the whole area of one side of a recording medium. If a line head is used, image recording can be performed on the entire surface of the recording medium simply by relatively moving (scanning) the recording medium and the line head in a direction (scanning direction) orthogonal to the arrangement direction of the recording elements. Can be. Therefore, according to the printer using the line head, image recording can be performed quickly and with a simple operation without moving the recording head or intermittent conveyance of the recording medium. On the other hand, line heads have disadvantages such as higher cost, lower yield, and lower reliability than recording heads used in serial type printers. Further, even if a part of the recording element is damaged, it is necessary to replace the entire expensive line head, and there is a disadvantage that the cost for repair is high.

In order to solve such a problem of the line head, a small print head as a base (hereinafter, referred to as a short head for convenience) is provided with a staggered print head in which the ends of the print element rows are overlapped in the scanning direction. Arranged in the direction of the recording element row
One line head is configured (see Japanese Patent Publication No. 4-38589). According to such a line head, the line head can be configured while taking advantage of the small and short head such as cost, yield, and reliability. Moreover, if some recording elements are damaged, only the short head of that part needs to be replaced,
It is also very advantageous in terms of costs for repairs and the like.

[0006]

Here, in the line head in which the short heads are arranged as described above, the seam between the adjacent short heads (the driving recording element of the adjacent short head in the recording element row direction). It is necessary to accurately position and arrange each short head so that the recording elements at the (switching position) match the specified pitch. If the seam is displaced, the recording position (in the case of an ink jet, the ink landing position on the image receiving paper) is also displaced due to the dislocation. In severe cases, streak-like white spots occur. However, the pitch of the recording elements is, for example, 6
About 42 μm at 00 dpi, about 84 μm even at 300 dpi
And very narrow. Therefore, it is substantially very difficult to accurately position a large number of short heads to form a line head having a joint at a specified pitch.

To cope with this, various methods have been proposed for adjusting the joints of the short heads without performing high-precision alignment of each short head. For example, Japanese Patent Application Laid-Open No. 6-255175 discloses that in a line head in which short heads are arranged, by randomly changing the driving of the recording element at the seam, it is possible to make the image quality deterioration at the seam substantially invisible. A recording device is disclosed. However, in this method, since the driving of the recording element at the seam is changed at random for each line, the recording control of the line head becomes very complicated.

Japanese Patent Application Laid-Open No. 2000-190484 discloses that, in a line head in which short heads are arranged, the pitch of the recording elements (preferably, only the overlapping portion) of one of the short heads adjacent to each other is changed. There is disclosed a line head which is so different that it cannot be visually recognized.
According to this line head, the recording element rows of adjacent shortened heads are overlapped by a predetermined length or more, and there is a recording element whose position matches in the arrangement direction due to the difference in the pitch. Thereby, the gap between the joints can be eliminated. However, in order to manufacture this line head, it is necessary to manufacture two types of short heads having different recording element pitches, which is disadvantageous in cost. In addition, in order to ensure that one of the recording elements coincides between adjacent short heads, it is necessary to overlap the recording element rows by an amount corresponding to the difference in pitch between the heads. Disadvantageous.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and a plurality of base recording heads (short heads) are arranged, preferably in a zigzag pattern, to make them longer. In the recording head, high-quality image recording can be performed while minimizing image quality deterioration at the joints without performing high-precision alignment of each short head. An object of the present invention is to provide a recording head having good head use efficiency and an ink jet printer using the recording head.

[0010]

In order to achieve the above object, a recording head according to the present invention comprises a plurality of basic heads having a plurality of recording elements arranged in one direction arranged in the arrangement direction of the recording elements. A recording head, wherein the basic head has at least one or more recording elements arranged at a pitch smaller than a specified pitch at at least an end on the side where the adjacent basic head exists, and the adjacent basic head is Different in the direction orthogonal to the arrangement direction, and in the arrangement direction, the recording element rows are arranged at positions not separated from each other by the specified pitch, and further, each base head is located at an end where an adjacent base head exists. And a recording head for driving only a recording element selected so that an interval does not exceed the specified pitch and is closest to the specified pitch.

In such a recording head of the present invention,
Adjacent basic heads are preferably arranged such that their recording element rows overlap in the arrangement direction, and a pitch narrower than the specified pitch is a pitch obtained by dividing the specified pitch by an integer. Preferably, furthermore, in the basic head, only the endmost recording elements on the side where the adjacent basic head is present are arranged at a pitch of half the specified pitch, and each basic head is arranged in the arrangement direction. , The endmost recording elements are arranged so as to be located between the second and third recording elements from the end of the adjacent basic head, and the adjacent basic heads are located at the extreme ends of each other. According to the distance from the third recording element from the end, if this distance is smaller than half the specified pitch, one of the basic heads is the second from the end and the other is the shortest. Department only, it It is not driving the recording element, on the contrary, if larger than half the spacing of said specified pitch on both basal head both preferably does not drive only the second recording element from the end.

Further, an ink jet printer of the present invention provides an ink jet printer using the recording head of the present invention.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a recording head and an ink jet printer according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings. In addition, the present invention
Not limited to inkjet printers, such as dot impact printers, thermal printers, sublimation printers, etc.
The present invention can be suitably used for various recording heads (image recording apparatuses) using a recording head in which recording elements are arranged in one direction.

FIG. 1 shows an example of the ink jet printer of the present invention using the recording head of the present invention. In FIG. 1, (A) is a front view (view from the main scanning direction) conceptually showing the configuration of the ink jet printer.
(B) is a conceptual diagram of the ink jet printer viewed from an oblique direction.

The ink jet printer 10 (hereinafter referred to as the printer 10) includes an ink jet recording head 50.
As a recording head 50 (hereinafter, referred to as a recording head 50), a so-called line head in which nozzles 52 (recording elements) that eject ink exceed the length of at least one side of the corresponding maximum size image receiving paper P is used. Used. This printer 1
Numeral 0 is a known inkjet printer basically except that the recording head 50 is the recording head of the present invention.

Here, the present invention is not limited to a line head (a printer using a line head) as shown in the figure, but rather intermittently transports the image receiving paper P (recording medium) and moves the recording head by the carriage. Scanning is combined with the receiving paper P
During the stop, the recording head is scanned in the direction orthogonal to the arrangement direction of the recording elements to perform image recording, and after one scan, the image receiving paper P is conveyed by a predetermined length in the direction orthogonal to the scanning direction. By repeating scanning by the recording head, an image may be recorded on the entire surface of the image receiving paper P, that is, a so-called serial type may be used.

The printer 10 shown in FIG. 1 includes a recording unit 12 for recording an image by a recording head 50 and a supply unit 1.
4, preheating section 16, and discharge section 18 (FIG. 1 (B)
Is omitted). In addition, the printer 10 is installed in various ink jet printers such as a maintenance unit for cleaning the recording head 50 and a cap for the recording head 50 for preventing the nozzle 52 from drying and clogging. It is a matter of course that various known members and units may be provided.

The supply unit 14 includes a pair of transport rollers 20 and 2
2 and guides 24 and 26, and conveys the image receiving paper P such as recording paper upward from the horizontal direction and supplies it to the preheating unit 16.

The preheating section 16 includes a conveyor 28 including three rollers and an endless belt, and a conveyor 2.
8, a pressure roller 30 pressed against the endless belt from outside, a heater 32 pressed from inside the conveyor 28 via the endless belt via the endless belt, the housing 16a covering these, and the inside of the housing 16a is exhausted. And an exhaust fan 34 that operates. Such a preheating unit 16 is for heating (receiving) the image receiving paper P before image recording by ink jet, thereby promoting drying (fixing) of the ink that has landed on the image receiving paper P. Specifically, the image receiving paper P transported from the supply unit 14 is heated from the recording surface side by the heater 32 and transported to the recording unit 12 while being nipped and transported by the conveyor 28 and the pressure roller 30.

The recording section 12 includes a recording head 50 according to the present invention.
, A recording control unit 56, and a recording medium conveying unit 58. The recording head 50 includes
An ink tank (not shown) is loaded.

As described above, the recording head 50 is a so-called line head in which the nozzles 52 for ejecting ink are arranged over a length exceeding one side of the image receiving paper P. The direction is defined as an arrow x direction in FIG. 1 (in FIG. 1A, a direction perpendicular to the paper surface). Accordingly, the illustrated printer 10 records an image on the entire surface of the image receiving paper P by scanning the recording head 50 and the image receiving paper P once in a direction orthogonal to the nozzle row direction (hereinafter, referred to as a scanning direction). it can. In the illustrated example, image recording is performed by transporting the image receiving paper P in the scanning direction indicated by the arrow y in the figure.

Here, the recording head 50 according to the present invention
A line head is constructed by arranging a plurality of small print heads (short heads 54) as bases in the nozzle row direction instead of one long print head. FIG. 2A shows a recording head 5 used in the present invention.
FIG. 2 conceptually shows a plane 0 (viewed from the nozzle 52 side).

In the illustrated example, a recording head 50 (short head 54) having an arrangement of one nozzle 52 (nozzle row) and corresponding to monochrome image recording is illustrated in order to clarify the configuration and operation. I do. However,
The recording head of the present invention is not limited to this, and various configurations can be used. For example, the short head may be a center-feed type top shooter type recording head having two nozzle arrays (nozzle rows) that eject ink of the same color. Alternatively, K (black) ink, M (magenta) ink, C (cyan) ink, and Y (yellow) ink, or further, a color image having a nozzle row for ejecting inks such as light C and light M, respectively. It may be a recording head. The printer 10
Alternatively, a color image may be recorded by arranging a plurality of recording heads 50 as shown in FIG. 2A in the scanning direction.

As will be described later, the recording head of the present invention can adjust the position of each short head without particularly high precision.
It is possible to minimize streak-like density unevenness and white spots due to seam position shift, and the effect is particularly remarkable when a color image is recorded. Therefore, the recording head of the present invention preferably has one short head (chip) having a nozzle row corresponding to a plurality of colors, preferably a nozzle row of four or more colors.

As shown in FIG. 2A, the recording head 50 has five short heads 54 (54a
To 54e) to form a line head. In the recording head 50 of the present invention, the adjacent short heads 54 are located at different positions in the scanning direction and in the nozzle row direction (that is, when viewed from the scanning direction). The nozzle rows are preferably arranged so as to overlap each other so as not to be separated from the prescribed pitch. Further, in the illustrated example, as a preferred embodiment, the short heads 54 are alternately arranged in the scanning direction, that is, arranged in a staggered manner (staggered). Thereby, the positional deviation of the nozzle row of each short head 54 in the scanning direction can be minimized.
The positional deviation in the scanning direction can be easily corrected by adjusting the ejection timing of the ink from each short head 54.

The short head 54 includes a nozzle 52, a heater serving as an ink discharge unit arranged corresponding to each nozzle 52, an ink flow path for supplying ink to each heater (nozzle 52), and a heater driving unit (for example, a driving unit). (LSI) and the like. The short head 54 may be of a so-called top shooter type (face inkjet) or a side shooter type (edge inkjet). Further, the method is not limited to a so-called thermal inkjet that discharges ink by heating with a heater, and the ink is discharged by vibrating a diaphragm in an ink chamber using a piezo element or electrostatic force. May be.

As described above, in a line head (recording head) in which such short heads are arranged, in order to record a high-quality image without stripe-like density unevenness or white spots, a nozzle is required. Seam (in the nozzle row direction,
It is necessary to arrange the short heads in such a manner that the nozzle pitch at the drive nozzle switching position in the adjacent short head) is accurately adjusted, and the nozzle pitch is, for example, 600d.
Since it is as fine as about 42 μm in pi, it is practically difficult to exactly match this.

On the other hand, in the recording head 50 of the present invention, at the end of the short head 54 in the nozzle row direction (hereinafter, the nozzle row direction is omitted), the pitch of at least one or more nozzles 52 is set to a specified pitch. The following, and
At the end, only the recording element selected so that the interval between nozzles does not exceed the specified pitch and is closest to the specified pitch is driven to be a seam. As a result, it is possible to minimize image quality deterioration such as streak-like density unevenness at the seam without performing high-precision positioning of the short head 54.

As a method of selecting a recording element serving as a seam, for example, a method of analyzing and determining the state of the recording element using an SEM or the like, a method of selecting a nozzle so that the least square sum of the pitch is minimized, Various methods are available, such as a method of actually recording and reading an image with a scanner or the like and performing image analysis or the like, and an appropriate method can be selected according to the performance and characteristics of the recording head 50. I just need.

In the present invention, the nozzle pitch may be set to the specified pitch or less only at the end on the side where the adjacent short head is located. Therefore, in the illustrated example, in the short heads 54a and 54e, the nozzles 52 at both ends may have a specified pitch or less, or only the inner end in the nozzle row direction may have a specified pitch or less.

A preferred example will be described below with reference to FIGS. 2B and 2C, which are schematic views near the joint between the short heads 54a and 54b.

In the illustrated example, two nozzles 5 at the ends are provided.
2 are arranged at a half pitch (P / 2) of the specified pitch P. For example, the recording head 50 (short head 54)
If recording is performed at 600 dpi, the specified pitch P is about 42 μm, and the nozzles 52a-C and 52
Only BB and 52b-D and 52b-E are arranged at a pitch of about 21 μm. Under the above conditions, both short heads 54 are arranged such that the shortest nozzle 54 is located between the second and third nozzles 54 from the other end in the nozzle row direction (arrow x direction). Be placed. That is, in the nozzle row direction, the short head 54
b of the nozzle 5b of the short head 54a.
So as to be located between 2a-A and the nozzles 52a-B,
Both short heads 54 are arranged. It should be noted that this level of alignment can be performed relatively easily.

Therefore, in the illustrated example, the short head 5
Three nozzles 52a-A, nozzle 52a on the end side of 4a
-B and the nozzles 52a-C, the three nozzles 52b-D on the end side of the short head 54b, the nozzles 52b-E and the nozzles 52b-F (hereinafter, when referring to individual nozzles, simply refer to the nozzles A to F To form a seam. Specifically, according to the distance W between the nozzle 52 at the end of one short head 54 and the third nozzle 52 from the end of the other short head 54, for example, the distance W between the nozzle A and the nozzle D Then, the nozzle 52 to be driven is selected to form a joint. In other words, the third from the other short head side (the number of nozzles 52 with a narrow pitch plus one)
The distance between the nozzle A and the nozzle F is pitch P × 2
Is selected, the nozzle 52 to be driven is selected, and a seam is formed.

For example, when the distance W between the nozzles A and D is smaller than P / 2 [W <P / 2], that is, when the distance between the nozzles A and F is less than 2P, FIG.
As shown in (B), the nozzles B (or E), C and D are not driven (the nozzles 52 that are not driven are shown in white), that is, the image is formed by using (selecting) other nozzles 52. Make a record. Therefore, in this case,
At the joint, only the pitch between nozzles A and E is (P-
(W + P / 2)). Conversely, when the distance W between the nozzles A and D is larger than P / 2 [W> P /
2] That is, when the interval between the nozzles A and F exceeds 2P, image recording is performed without driving the nozzles B and E, as shown in FIG. 2C. That is, in this case, at the joint, the pitch between the nozzles A and D and the pitch between the nozzles C and F becomes an error of (P−W), and the nozzle C
And D have an error of ((3P / 2) -W).
If W = P / 2 (nozzles B and E match), if the image is recorded without driving the nozzles B (or E) C and D, the nozzle pitch at the seam is regulated. The pitch is P.

As is clear from the above description, according to the present invention, in any case, the nozzle pitch at the seam is between P / 2 and P, for example, at 600 dpi, the nozzle pitch at the seam is 21 μm-42 μm.
Can be. That is, even if the positioning of the short head 54 is not performed with high accuracy, the nozzle pitch does not exceed the specified pitch P at the seam, and the error of the nozzle pitch is minimized, and the streak shape corresponding thereto is reduced. Image quality deterioration such as density unevenness can be minimized. In addition, according to the present invention, the same short head 54 can be used for all of the recording heads 50, and the number of nozzles 52 that overlap between adjacent short heads 54 can be minimized. That is, the recording head 50 of the present invention is excellent in production cost and design cost, and efficiently utilizes the nozzle array of each short head 54, for example, by using a minimum number of short heads 54 as a line head (long head). ) Can be formed.

In the illustrated printer 10, the driving of the recording head 50 is controlled by a recording control unit 56.
The recording control unit 56 supplies a driving signal corresponding to the supplied image data to a heater driving unit (driving LS) of the recording head 50.
I) to drive the recording head 50. here,
The recording control unit 56 records data of the non-driven nozzles 52 selected according to the interval W. The recording control unit 56 controls the recording head 50 so as to perform image recording without using the data. Control the drive.

The nozzle 52 that is not driven is, for example,
Inspection may be performed in advance at the time of assembling, factory shipment, or the like to find the interval W, the nozzle 52 not to be driven may be selected, and input to the recording control unit 56 as calibration data. Alternatively, the printer 10 records a calibration chart or the like, reads the calibration chart, reads the interval W according to the result, and determines whether or not the recording control unit 56 (a separately provided selection unit can be used) is not driven. 52 may be selected. At this time, the chart reading means may be built in the printer 10 or the recording control unit 56 may receive data from an external reading device. Further, the data of the nozzles 52 that are not driven are input to the control unit of the printer 10, from which a control instruction is transmitted.
6 may be output.

Here, in the recording head 50 of the present invention, although at a minimum, there is an error in the nozzle pitch at the seam, and the image quality is reduced accordingly. Therefore, in the present invention, it is preferable to correct image quality deterioration caused by an error in the nozzle pitch at the seam by image processing.

The correction method is not particularly limited, and various known methods can be used. For example, a method of setting and correcting a correction coefficient of image data, a method of controlling by controlling an amount of ink ejected from each nozzle (for example, by controlling a heater driving time or the like), a method of correcting the same, and a Japanese Patent Application No. 2000-2568 by the present applicant.
No. 94 is exemplified. In addition,
The method of controlling the correction coefficient and the ink amount may be set as appropriate, for example, by recording an image having a uniform density and according to the obtained image. Note that the correction may be performed by the recording control unit 56 or may be performed by the image processing unit installed in the printer 10.

As described above, the recording head 50 of the present invention
In the method, the error of the nozzle pitch at the seam is minimized. Therefore, according to the recording head 50 of the present invention, even when performing image processing for correcting the nozzle pitch error of the seam, the image correction amount (the amount of change in image data from the original) is small, and the effect of correction is small. Therefore, high-quality image recording can be performed.

As described above, such a recording head 50
In the recording section 12 having the recording control means 56, a recording medium transport means 58 is disposed. Recording medium transport means 58
Is a conveyor 66 composed of rollers 60a and 60b, a suction roller 62, and a porous endless belt 64.
And a nip roller 68 pressed by a roller 60a via a porous endless belt 64 (omitted in FIG. 1B).
And a suction box 70 arranged in the conveyor 66.

The recording head 50 is arranged with the nozzle 52 facing the suction roller 62. Also, the recording medium conveying means 5
Numeral 8 conveys the image receiving paper P continuously at a predetermined speed in a scanning direction (arrow y direction) orthogonal to the nozzle row direction (arrow x direction). Therefore, the image receiving paper P supplied from the preheating unit 16 is scanned over the entire surface by the recording head 50, and an image is recorded by ink ejected from each nozzle 52. The conveyor 66 is provided with a perforated endless belt 64.
, And has a suction roller 62 and a suction box 70. Therefore, the image receiving paper P is conveyed while being attracted to the perforated endless belt 64, and an image is recorded on the recording head 50 in a state where it is appropriately kept at a predetermined position.

The image receiving paper P on which the image has been recorded is delivered to a discharge unit 18.
And is conveyed by a pair of conveying rollers 72 and a discharge roller 74, and is discharged to, for example, a discharge tray (not shown).

In the above example, the short head 54 constituting the recording head 50 is configured such that the two nozzles at the end portions have the specified pitch P
The nozzle pitch at the joint is set to be equal to or less than the specified pitch and the error is minimized as described above. However, the present invention is not limited to this. For example, the pitch of the three nozzles at the end may be reduced to 1/3 pitch, or the pitch of the four nozzles at the end may be reduced to 1/4 pitch. The error may be minimized by selecting the nozzles that are not driven according to the positional relationship of the nozzles at the end of.

FIG. 3 shows that the pitch of the three nozzles at the end is 1
A conceptual diagram of an example in which the pitch is set to / 3 is shown. As shown in FIG. 3A, when the interval between the fourth nozzles (the number of nozzles with a narrow pitch plus one) from the other side (the other short head side) is less than the pitch P × 2, the hatched area As shown by, the upper short head drives the fourth nozzle from the other side, and the lower short head drives the third and fourth nozzles from the other side to form a seam. On the other hand, when the fourth nozzle interval from the other side exceeds the pitch P × 2, the distance between the third nozzle from the other side, ie, the interval p between the third nozzles from the other side, is small. The nozzle to be driven is selected accordingly.

As shown in FIG. 3B, when the interval p is less than 1/3 of the pitch P [p <P / 3], the upper short head is connected to the other side, as indicated by oblique lines. The third, fourth and lower short heads from the side drive the fourth nozzle from the other side to form a seam.
In addition, as shown in FIG.
Is greater than 1/3 and less than 2/3 [P / 3
<P <P2 / 3] illustrates an example of a method in which both the upper short head and the lower short head drive the first and fourth nozzles from the other side to form a seam, as indicated by oblique lines. Is done.

Here, in the example shown in FIG. 3B, a portion between the nozzles exceeding the pitch P occurs at the joint. However, when the pitch is 1/3 or less, the error is small because the distance between nozzles is very narrow.
Sufficient correction can be made by dot control (for example, adjustment of ink ejection amount by heater driving time, image data correction, etc.). However, the pitch P
Depending on the size of the print head and the characteristics of the recording head, the target image quality may not be obtained by the dot control correction. At that time, for example, the upper short head drives only the fourth nozzle from the other side, and the lower short head is
The first, third, and fourth nozzles from the other side may be driven to form a seam, and the distance between the nozzles at the seam may not exceed the pitch P. Which one to choose depends on the image quality and performance required for the printhead (printer),
What is necessary is just to select suitably according to the characteristics etc. of a recording head.

FIG. 4 shows that the pitch of the four nozzles at the end is 1
A conceptual diagram of an example in which the pitch is / 4 is shown. As shown in FIG. 4A, similar to the example shown in FIG.
When the interval between the nozzles (same as above) is less than the pitch P × 2, the upper short head is the fifth from the other side, and the lower short head is the fourth from the other side, as indicated by oblique lines. A method of driving the fifth nozzle to form a seam is exemplified. On the other hand, when the fifth nozzle interval from the other side exceeds the pitch P × 2, similarly to the example shown in FIG. 3, the last nozzle of the narrow pitch nozzle in the short head, that is, from the other side The nozzle to be driven is selected according to the interval p between the fourth nozzles.

For example, as shown in FIG. 4B, when the interval p is less than 1/4 of the pitch P [p <P / 4]
The upper short head is the fourth and fifth from the other side, and the lower short head is 5
A method of driving the second nozzle to form a seam is illustrated. Also, as shown in FIG. 4C, when the interval p is more than 1/4 of the pitch P and less than 2/4, [P / 4 <p <P2 / 4] is hatched. As shown, both upper and lower short heads drive the second and fifth nozzles from the other side to form a seam. Further, as shown in FIG. 4D, the interval p exceeds 2/4 of the pitch P, and
In the case of [P2 / 4 <p <P3 / 4], both the upper short head and the lower short head drive the first and fifth nozzles from the other side, as indicated by oblique lines. Then, a method of forming a seam is exemplified.

Here, in the example shown in FIG. 4 (B), similarly to the example shown in FIG. 3 (B), there occurs a portion where the interval between nozzles exceeds the pitch P at the seam. This is the same as in the previous example. Correction may be performed by dot control according to the characteristics of the recording head, or if correction is not possible, for example, the upper short head may be 5 mm from the other side.
It is sufficient to drive only the No. 1 nozzle and the lower short head drives the second, fourth and fifth nozzles from the other side to form a seam.

Although the recording head and the ink jet printer of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the gist of the present invention. Of course, you can do it.

[0052]

As described above in detail, according to the present invention, in a recording head in which the basic recording heads are arranged in a zigzag manner and lengthened, the positioning of each short head is improved. Even without precision, high-quality image recording can be performed while minimizing the error of the nozzle pitch at the seam.
Further, it is possible to realize a recording head and an ink jet printer in which the utilization efficiency of each basic head is good.

[Brief description of the drawings]

FIG. 1 is an example of an inkjet printer using the present invention, in which (A) shows a schematic front view and (B) shows a partial schematic perspective view.

FIGS. 2A, 2B and 2C are schematic plan views for explaining a recording head used in the ink jet printer shown in FIG.

FIGS. 3A, 3B, and 3C are conceptual diagrams for explaining another example of the recording head of the present invention.

FIGS. 4A, 4B, 4C, and 4D are conceptual diagrams for explaining another example of the recording head of the present invention.

[Explanation of symbols]

 Reference Signs List 10 (inkjet) printer 12 recording unit 14 supply unit 16 preheating unit 18 discharge unit 20, 22, 72 transport roller pair 24, 26 guide 28, 66 conveyor 30 pressure roller 32 heater 34 exhaust fan 50 recording head 52 nozzle 54 short head 56 Recording control unit 58 Recording medium conveying means 60a, 60b Roller 62 Suction roller 64 Porous endless belt 68 Nip roller 70 Suction box 74 Discharge roller pair

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA08 EA24 FA13 HA07 HA22

Claims (5)

[Claims] 1. A recording head in which a plurality of basic heads having a plurality of recording elements arranged in one direction are arranged in an arrangement direction of the recording elements, wherein the basic heads are arranged at a pitch smaller than a specified pitch. At least one or more recording elements at an end on the side where the adjacent basic heads are present. The adjacent basic heads are different from each other in a direction perpendicular to the arrangement direction, and are mutually different in the arrangement direction. The rows are arranged at positions not spaced apart from the specified pitch.Furthermore, at the end where the adjacent base heads are present, the spacing does not exceed the specified pitch and is closest to the specified pitch. A print head that drives only the print element selected in (1). 2. The recording head according to claim 1, wherein adjacent basic heads are arranged such that the recording element rows overlap each other in the arrangement direction. 3. The recording head according to claim 1, wherein the pitch smaller than the specified pitch is a pitch obtained by dividing the specified pitch by an integer. 4. The basic head according to claim 1, wherein only the endmost recording elements on the side where the adjacent basic heads are located are arranged at a pitch of half the prescribed pitch. In the direction, the endmost recording elements are arranged so as to be located between the second and third recording elements from the end of the adjacent base head, and the adjacent base heads are located at the endmost positions of each other. When the distance is smaller than half of the specified pitch according to the distance between the recording element and the third recording element from the end, one of the basic heads is up to the second from the end, and the other is Only the shortest portion does not drive the recording element, and conversely, if the interval is wider than half of the specified pitch, both basic heads do not drive only the second recording element from the end. The recording head according to any one of claims 1 to 3. 5. An ink jet printer using the recording head according to claim 1.