JP3418986B2 - Ink jet recording head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type ink jet recording head that forms an ink reservoir on a recording medium such as recording paper by ejecting ink droplets according to a print signal, and more specifically, The present invention relates to the arrangement of nozzles for ejecting ink drops and the shape of ink chambers.

2. Description of the Related Art In recent years, while an ink jet type recording apparatus capable of outputting a high density recorded image is required, an ink jet type recording head which realizes a recording density higher than a linear array density of nozzles is disclosed in JP-A-60-147348. There is. In the ink jet type recording head for recording in this publication, a recording head having nozzles arranged in a straight line is obliquely arranged with respect to the main scanning direction to increase the recording density. However, in the structure of this recording head, there is a problem that the print quality is greatly affected, such as the possibility of unevenness in the pitch of the recording pixels due to dimensional errors such as mounting dimensions on the carriage.

On the other hand, in the ink jet recording head described in JP-A-4-312859, the nozzles are arranged in a zigzag pattern on a plurality of diagonal straight lines as shown in FIG. The print quality has been improved.

However, in order to realize high-density recording with the ink jet recording head described in Japanese Patent Laid-Open No. 4-312859, it is necessary to narrow the pitch between the nozzles, that is, to reduce the angle α. In order to prevent the occurrence of crosstalk due to the interference between the ink chambers, the angle is substantially restricted. In addition, because of the configuration having a plurality of bent portions, the depth of ink penetration is different between the recorded image at the bent portion and the recorded image at the peripheral portion, resulting in a plurality of unevenness in the entire recorded image as shown in FIG. It happened.

Therefore, an object of the present invention is to provide a highly integrated ink jet recording head that can realize high recording density and high printing quality.

DISCLOSURE OF THE INVENTION An inkjet head according to the present invention is an inkjet recording head having a plurality of nozzles for ejecting ink droplets and a plurality of ink chambers communicating with the nozzles, wherein the plurality of nozzles move the recording head. Are arranged at regular intervals along the first line segment and the second line segment, which are line segments inclined in directions opposite to the main scanning direction, which is above the first line segment. Forming a substantially V-shaped nozzle array with the first nozzle array located on the second line segment and the second nozzle array located on the second line segment, and the first nozzle array and the second nozzle array The nozzles in a row are arranged at a constant pitch in the sub-scanning direction, the ink chambers are arranged outside the V-shaped nozzle row, and the first nozzles are arranged adjacent to the second nozzle row in the previous period. For the nozzles at the end of the nozzle row, The nozzle positions of the end portions of the second nozzle row, which are close to the first nozzle row, are arranged so as to be offset in the main scanning direction so as not to overlap in the sub scanning direction, and
Recording is performed using the first nozzle row and the second nozzle row.

Further, the ink chamber is formed by a multi-step curved surface such that the radius in the vicinity of the nozzle is smaller than that of other portions.

Further, it has a rhombus-shaped nozzle row in which two substantially V-shaped nozzle rows are combined, and after thinning printing is performed by one of the V-shaped nozzle rows, the other V-shaped nozzle row is used to fill the gap. It is characterized in that it is configured to be recordable.

Further, it is characterized in that the flow passage ports formed by stacking the flow passages from the ink chambers to the nozzles are gradually shifted.

The shift amount in the main scanning direction is such that the nozzles of the second nozzle row are arranged between the nozzles of the first nozzle row.

From the nozzles at the ends of the first nozzle row that are close to the second nozzle row and the nozzles at the ends of the second nozzle row that are close to the first nozzle row, the plurality of nozzles Nozzles at the ends of the first nozzle row, which are arranged along the first or second line segment and are spaced apart from each other by a distance wider than a constant distance, and are close to the second nozzle row, and It is characterized in that the nozzles are arranged so that the pitches in the sub-scanning direction are the same as those of the nozzles at the end portions of the second nozzle row that are close to the first nozzle row.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of nozzle arrangement and ink chamber arrangement of an ink jet recording head of the present invention.

FIG. 2 is a diagram showing a printing state of the first embodiment of the present invention.

FIG. 3 is an enlarged view of a part of the nozzles of the first embodiment of the present invention.

FIG. 4 is a graph showing the positional deviation of pixels according to the first embodiment of the present invention.

FIG. 5 is a perspective view illustrating a mounting state of the ink jet recording head of the present invention.

FIG. 6 is a perspective view showing a carrying mechanism of the ink jet recording head of the present invention.

FIG. 7 is a diagram showing a print pattern of the first embodiment of the present invention.

FIG. 8 is a diagram showing an ink jet recording head of another embodiment of the present invention.

FIG. 9 is a diagram showing an ink jet recording head of another embodiment of the present invention.

FIG. 10 is a diagram showing an ink jet recording head of another embodiment of the present invention.

FIG. 11 is a diagram for explaining the ink jet recording head of the present invention.

FIG. 12 is a diagram for explaining the nozzle arrangement and the ink chamber arrangement in the conventional technique.

  FIG. 13 is a diagram illustrating a printing state of a conventional technique.

BEST MODE FOR CARRYING OUT THE INVENTION In order to describe the present invention in more detail, it will be described with reference to the accompanying drawings.

FIG. 1 is an illustration of the arrangement of nozzles and ink chambers of an ink jet recording head according to an embodiment of the present invention. First
In the figure, the recording head of the present embodiment includes nozzles 190 to 197 for ejecting ink droplets and an ink chamber communicating with them.
It has 170 to 177. Although not shown in the drawing, some ink chambers communicate with 32 nozzles in a row and 64 nozzles in total. In the figure, the nozzles are arranged at regular intervals along line segments L1 and L2 that are straight lines inclined in directions opposite to the x direction, which is the main scanning direction (movement direction when the carriage is mounted). This line segment is inclined with an inclination α such that the pitch p1 of each nozzle in the sub-scanning direction is 1/360 inch, and the line segment L1 and the line segment L2 are formed in a substantially V shape.

The ink chamber is arranged outside the V-shape formed by the line segments L1 and L2, and the width d4 of each ink chamber is 450 μm.
It is formed wide so that a sufficient ink ejection amount can be obtained, and the depth is formed to be 150 μm and deep so as to secure ink flow characteristics.

The pressurizing means for pressurizing the ink chamber configured as described above is formed by bonding a piezoelectric element to a vibrating plate forming the wall surface of the ink chamber or printing the piezoelectric element on the vibrating plate and firing it. Can be used.

The overall size of the nozzle of this embodiment is w = d1 × 24 = 13.55 m
m and h = p1 × 47 = 3.32 mm.

According to the recording head of the present invention, since the nozzles are arranged in a V-shape, there is a problem that a plurality of shading unevenness occurs in the recording head disclosed in Japanese Patent Laid-Open No. 4-312859 which is a conventional technique. As shown in FIG. 2, the area where the print density becomes high is limited to only the vicinity of the nozzle 192 in the central portion,
In the vicinity of 90, the density can be made uniform, and the unevenness of the density can be suppressed to a minimum at one place in the entire printing width b. As a result, even when a bit image such as a graphic is recorded using the recording head of the present embodiment, high quality output can be achieved without losing the texture.

Further, in this embodiment, as shown in FIG. 1, among the nozzles along the diagonal line segments L1 and L2 adjacent to each other, the diagonal line segment L2
The nozzles (nozzles 191, 195, 196, 197 in the figure) are displaced from the position of the nozzle 192 in the main scanning direction (-x direction in the figure) by d2 = d1 × 2.5 = p1 × 20, and the line segment L1 and line segment The distance p2 in the sub-scanning direction between the nozzle 192 and the nozzle 191 corresponding to the end of L2 was arranged to be the same pitch as p1. Further, the nozzles 194 and 191 were arranged so that the pitch was p1 × 3. FIG. 3 shows a partially enlarged view of the bent portion in which the nozzles are displaced. In the present embodiment, as shown in the figure, the nozzle row along the line segment L2 is displaced by 2.5 nozzles in the −x direction from the nozzle row along the line segment L1 and is between the nozzle 193 and the nozzle 194 of the line segment L1. A nozzle 191 along L2 is arranged at the position of d1 / 2. Thus, the shift amount d2 = d1 × 2.5 =
By arranging them with a shift of p1 × 20, it is possible to secure a sufficient printing density and to increase the shortest distance between the closest nozzles 191 and 194 to obtain sufficient rigidity of the wall between the ink chambers 171 and 174. Therefore, adverse effects such as crosstalk on ink ejection can be eliminated.

The shift amount d2 is set to d2 = d1 x 2.5 = p1 x 20 and an integer multiple of the print pitch p1, and the print timing of the nozzles (nozzles 191, 195, 196, 197 in the figure) shifted in the main scan direction is set to the basic timing (main In the embodiment, the basic timing interval corresponds to the pitch p1)
Is calculated by counting 20 nozzles for each nozzle 192). The basic timing in the main scanning direction can be directly obtained from the linear encoder output arranged in the same direction or the pulse number of the stepping motor for driving the recording head. In this embodiment, with such a configuration, without adding a special timing generation mechanism,
Pixels were accurately formed from the nozzle groups that were shifted in the main scanning direction, and high print quality was achieved.

Further, in this embodiment, the shape of the ink chamber in the vicinity of the nozzles is not a simple curved surface of R but a curved surface of smaller R in the vicinity of the nozzles, so that the distance between the adjacent nozzles can be made wider and the cross Interference such as talk can be eliminated more reliably, and curved surface R near the nozzle can be eliminated.
Shows a superior effect on the bubble discharge property as well.

In the present embodiment, the shortest distance d5 = 352.8 μm is the nozzle 191
Distance r1 = 100 μm from the center to the outer shape of the ink chamber 171, and distance r1 = 100 from the center of the nozzle 194 to the outer shape of the ink chamber 174.
The sum of μm is larger than d6 = r1 + r2 = 200μm, and r3 is 100μ
It can be made wider than m, and the rigidity of the wall between the ink chambers is kept extremely high.

The recording head of the present invention is less likely to cause deterioration in printing quality due to mounting errors or the like. The details will be described below.

Since the printing pitch p1 in this embodiment is 1/360 inch = 70.6 μm, it is desirable that the diameter of one pixel on the recording medium 1 is about 100 to 120 μm in consideration of completely covering the recording medium. . In this pixel size, the displacement of the pixel of 20 to 30 μm is visually perceived, which causes deterioration of print quality. In this embodiment, the nozzle 19 with the angle θ is used.
The displacement of 5 is expressed as Δx = h × π × θ / 180 in the x direction and Δy = d3 × π × θ / 180 in the y direction (h = p1 × 47 = 3.32m
m, d3 = d1 × 2.5 = 1.41 mm), and the actual displacement is as shown in FIG. 4 with respect to the angle θ. Generally, the angle θ is about 0.1 degrees including backlash and accuracy of parts, and the positional deviation is Δ
Since x is as small as 6 μm and Δy is 2.5 μm, it is possible to apply it while ensuring sufficient printing quality.

The recording head of the present invention can be easily mounted on an ink jet recording apparatus having a configuration in which the user can easily replace the recording head for the above reasons without causing a problem in mounting accuracy to the carriage.

As such a recording device, even a recording device having a simple supporting mechanism such as an arm 360 and a pin 361 as shown in FIG. 5 can be easily mounted. In this recording apparatus, the recording head 9 is moved in the main scanning direction (x direction in the drawing) relative to the recording medium while ejecting the ink droplets 50 from the nozzles 190 and the like to form pixels on the recording medium 1. To do. After the formation of pixels in the main scanning direction is completed in this way, the recording medium 1 is conveyed in the sub-scanning direction (y direction in the drawing) perpendicular to the main scanning direction, and then, in the margin portion of the recording medium 1 again in the main scanning direction (in the drawing Recording proceeds in the process of forming pixels in the (-x direction). The conveyance of the recording head is performed by driving the belt 6 with the stepping motor 10 via the pulley 5 as shown in FIG. Even if an error occurs in the feed amount in the main scanning direction due to the eccentricity of the pulley 5, the vibration of the belt 6, or the expansion and contraction due to the external environment, the printing using the recording head of the present embodiment is performed smoothly as shown in FIG. Since the pattern is a continuous pattern, there is an advantage that it is possible to provide high-quality printing without the visual disturbance of vertical lines and the like being noticeable.

FIG. 8 shows another embodiment of the present invention. In this embodiment, a part of the nozzle along the diagonal line segment L1 (nozzle 192 in the figure)
Is shifted in the main scanning direction (x direction in the figure). In this way, by displacing the nozzle 192 by a larger amount (d7 = d1 × 3) than the nozzle 191 which ejects the next ink, the ink droplets are ejected from the nozzle 192 to the recording medium at an early stage, and the pixels are dried, so that the pixels are quickly formed. Even if the next ink droplet from the nozzle 191 is formed and overlaps with the image formed by the ink droplet from the nozzle 192, the image formed by the nozzle 192 is dry, and therefore a partial collection of the ink droplets is generated. It is possible to prevent the density unevenness at the center of the print and further suppress it. In this embodiment, only the nozzle 192 is displaced, but if a plurality of nozzles are displaced, the effect of uneven density is further enhanced.

FIG. 9 shows another embodiment of the present invention. In this embodiment,
Nozzle arrays are arranged along a plurality of line segments L1, L2, L3, L4, and as examples, different colors are assigned such as black for L1, cyan for L2, magenta for L3, and yellow for L4.
Further, L1 and L2, L3 and L4 are separated in the main scanning direction (x direction),
By separating the nozzles 190 and 191, and the nozzles 192 and 193 from each other, different color inks flow into the nozzles 190, 191, 192, and 193 to prevent color mixture and turbidity.

FIG. 10 shows another embodiment of the present invention. This recording head is formed in a rhombus shape by combining two V-shaped nozzle arrangements. According to this nozzle arrangement, it is possible to perform thinning-out printing by one V-shaped nozzle at the time of recording in the main scanning direction and then perform recording by another V-shaped nozzle so as to fill the gap between them, which causes problems such as ink bleeding. Can be solved.

The configuration of the inkjet recording head for realizing the inkjet recording head of the present invention is as follows:
A laminated type ink jet recording head as shown in the figure is preferably used. According to this recording head, the ink chamber
Since it is possible to gradually shift the flow passage port in which the flow passage from 17 to the nozzle 2 is stacked, the position of the nozzle 2 can be shifted to the outside of the ink chamber rather than the end of the ink chamber 17. The position of the ink chamber can be reduced compared to the position of the nozzle. When such a configuration is adopted in the nozzle arrangement having the bent portion as in the embodiment of the present invention,
A sufficient distance can be secured between adjacent ink chambers, crosstalk can be sufficiently prevented, the distance between nozzles can be reduced, and nozzles can be arranged at high density. In FIG. 11, the ink is
The ink is supplied from the common ink chamber 11 to the ink chamber 17,
The piezoelectric element 20 pressurizes the vibrating plate 19 laminated on top of the vibrating plate 19 so that the vibrating plate 19 is ejected from the nozzle 2 through the flow path.

As described above, according to the present invention, it is possible to provide a highly integrated ink jet recording head capable of recording at a high recording density, suppressing printing unevenness, and not affecting recording quality due to mounting error.

INDUSTRIAL APPLICABILITY As described above, the inkjet recording head of the present invention is suitable for use in a recording device such as a printer, a facsimile and a copying machine.

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055

Claims (6)

(57) [Claims] 1. An ink jet recording head having a plurality of nozzles for ejecting ink droplets and a plurality of ink chambers communicating with the nozzles, wherein the plurality of nozzles is a main scanning direction which is a moving direction of the recording head. A first line segment that is inclined in directions opposite to each other
Line segment and a second line segment are arranged at regular intervals, and a first nozzle row located on the first line segment and a first nozzle row located on the second line segment. The two nozzle rows form a substantially V-shaped nozzle row, and the nozzles of the first nozzle row and the second nozzle row are arranged at a constant pitch in the sub-scanning direction, and the ink chamber is The nozzles that are arranged outside the V-shaped nozzle row and that are adjacent to the first nozzle row with respect to the nozzles at the end of the first nozzle row that are adjacent to the second nozzle row The nozzle positions at the ends of the second nozzle row are arranged so as to be offset in the main scanning direction so as not to overlap in the sub-scanning direction, and recording is performed using the first nozzle row and the second nozzle row. Inkjet recording head. 2. The ink jet recording head according to claim 1, wherein the ink chamber is formed by a multi-step curved surface whose radius in the vicinity of the nozzle is smaller than that of other portions. 3. A rhombus-shaped nozzle row that is a combination of two substantially V-shaped nozzle rows, wherein after thinning printing by one of the V-shaped nozzle rows,
The ink jet recording head according to claim 1, wherein the other V-shaped nozzle row is configured to be capable of recording so as to fill the space between them. 4. The ink jet recording head according to claim 1, wherein the flow passage ports formed by stacking the flow passages from the ink chambers to the nozzles are gradually shifted. 5. The ink jet recording according to claim 1, wherein the shift amount in the main scanning direction is such that the nozzles of the second nozzle row are arranged between the nozzles of the first nozzle row. head. 6. The nozzles at the end portions of the first nozzle row proximate to the second nozzle row and from the nozzles at the end portions of the second nozzle row proximate to the first nozzle row, A plurality of nozzles are arranged along the first or second line segment and are spaced apart from each other by a distance wider than a constant distance, and an end of the first nozzle row that is close to the second nozzle row. And a nozzle arranged so that the pitch in the sub-scanning direction is the same as that of the nozzle of the first nozzle row and the nozzle of the end portion of the second nozzle row that is adjacent to the first nozzle row. The inkjet recording head according to item 1.