JPH07214796A - Ink jet print head - Google Patents

Abstract

PURPOSE:To dispose nozzles on the straight line which eject a phurality of kinds of inks each having different color and prevent the mixing of colors. CONSTITUTION:On a head tip 1, nozzles for different colors are disposed and dummy nozzles 4 are disposed therebetween. Dummy nozzle passages 5 are provided to the dummy nozzles 4. A waste ink-discharging communication passage 10 communicating with the dummy nozzle passages 5 is provided to a heat radiation plate 9. A waste ink suction body 11 is provided on a face of the heat radiation plate 9 opposite side of the head tip 1. When an ink gathered on a nozzle face reach the dummy nozzle 4, the ink is sucked to the dummy nozzle 4 by a capillary force to be sucked to the waste ink suction body 11 through the dummy nozzle passage 5. Thereby, the mixed ink on the nozzle face is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet print head used for a color printer.

[0002]

2. Description of the Related Art Conventionally, ink jet color printers require ink jet print heads corresponding to the number of ink color types used, and ink jet print heads for each color are known. In such an inkjet color printer, four colors are generally used, and therefore, it is necessary to use four heads. As described above, when a plurality of inkjet print heads are used, there is a problem that a carriage for mounting the inkjet print heads becomes large and a device also becomes large.
This problem is particularly noticeable in the disposable print head in which the inkjet print head and the ink tank are integrally formed. Further, in the disposable print head, since the print head is a consumable item, the user needs to always have four heads as spares, which forces an extra inventory.

In order to improve this, for example, Japanese Patent Laid-Open No.
As described in JP-A-3-87242, an integrated color inkjet printhead in which a plurality of colors are formed in one cartridge body has been proposed. This inkjet printhead has a structure in which nozzles are two-dimensionally arranged on a heating element substrate so that nozzles of different colors are not adjacent to each other. Therefore, it is necessary to correct the ejection timing of each nozzle by the amount of positional deviation, which complicates drive control of the print head.

On the other hand, for example, Japanese Patent Laid-Open No. 3-189
The third embodiment of Japanese Patent No. 167 and the technology described in Japanese Patent Laid-Open No. 2-235642 propose an inkjet printhead in which nozzles of different colors are arranged on a straight line. In an inkjet printhead in which nozzles of different colors are arranged on a straight line, nozzles of different colors are arranged relatively close to each other. Therefore, color mixing, in which inks adhering to the nozzle surface are mixed, is a serious problem. This color mixing occurs due to the scattering of ink droplets during normal printing and the withdrawal and diffusion of ink during priming. Further, a method of removing the ink adhering to the head surface with a wiper blade to prevent the occurrence of defective ejection of ink has been considered, but when ink of a different color adheres to the head surface, The ink is mixed. The color mixture causes the image quality defect in the subsequent print recording.

Further, for example, Japanese Patent Laid-Open No. 3-236965.
Japanese Unexamined Patent Publication No. 3-240551 and Japanese Unexamined Patent Publication No.
It is known that a waste ink absorber is provided on the side surface of the head as seen in Japanese Patent Application Laid-Open No. 37566 and Japanese Patent Application Laid-Open No. 4-126259. In the inkjet print head having such a structure, since the ink collected by the wiper blade provided for removing the ink adhering to the head surface is absorbed by the waste ink absorber,
Secondary obstacles such as accelerated wiper blade contamination,
Alternatively, the ink generated by the wiper blade does not repel. However, with this method alone, in an inkjet printhead in which nozzles for ejecting ink of different colors are provided on a straight line, the ink scraped by a wiper blade mixes the colors, and the mixed ink is pushed into the nozzle again. Sometimes. Therefore, it is not possible to prevent color mixing of the inkjet print head in which the nozzles for ejecting inks of a plurality of colors are arranged on a straight line.

Further, for example, Japanese Patent Publication No. 2-4429 discloses an ink jet recording apparatus in which an ink return hole is arranged together with a nozzle, the return hole is communicated with an ink storage section, and ink is sucked by a negative pressure. Has been done. However, when a plurality of colors of ink are used in this device, there is a risk that the inks will be mixed in color before reaching the return hole. Therefore, the openings of the nozzles arranged below are exposed to the mixed color ink. Further, although the ink that has reached the return hole is returned to the ink storage unit, it is impossible to reuse the mixed ink. Thus, it cannot be said that it is an effective means for an inkjet print head in which nozzles for ejecting ink of different colors are arranged on a straight line.

Further, in Japanese Patent Application No. 5-195198,
A technique is described in which dummy nozzles that do not eject ink are provided between nozzles of different colors. According to this technique, since the mixed color ink is sucked by the capillary force of the dummy nozzle, the problem of color mixture can be avoided.
However, the unnecessary ink sucked by the capillary force of the dummy nozzle needs to be collected again by vacuum or the like, and the operation causes the ink to be mixed again.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an inkjet printhead in which a plurality of nozzles for ejecting inks of different colors are arranged in a straight line does not cause color mixture. It is intended to provide a printhead.

[0009]

SUMMARY OF THE INVENTION According to the present invention, in an ink jet print head in which nozzles for ejecting a plurality of different color inks are arranged in a straight line, nozzles for ejecting a plurality of different color inks are formed. A head chip in which a predetermined number of capillaries are arranged between the nozzles for ejecting ink, a heat radiating plate having an ink discharging opening arranged in contact with the head chip, and the heat radiating plate on the opposite side of the head chip. A discharge ink absorber provided so as to be in contact with the heat dissipation plate, wherein the capillary communicates with the ink discharge opening provided on the heat dissipation plate, and further communicates with the waste ink absorber. It is a feature.

[0010]

According to the present invention, in an ink jet print head in which a plurality of nozzles for ejecting inks of different colors are arranged in a straight line, a capillary tube is provided between nozzle groups of different colors, and color mixture occurs on the surface of the head chip. Ink is absorbed by capillary force. Further, the capillary tube communicates with the waste ink absorber through the ink discharge opening provided in the heat dissipation plate, and allows the waste ink absorber to absorb the mixed color ink absorbed in the capillary tube. As a result, mixed color ink can be eliminated, color mixing does not occur during printing, and good image quality can be maintained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of an embodiment of an ink jet print head of the present invention, FIG. 2 is a sectional view of a nozzle portion, and FIG. 3 is a sectional view of a dummy nozzle portion. In the figure, 1 is a head chip, 2, 2a, 2b, 2
c is a nozzle, 3, 3a, 3b, 3c are ink flow paths, 4,
4a, 4b are dummy nozzles, 5, 5a, 5b are dummy nozzle openings, 6a, 6b, 6c are ink tanks, 7a, 7
Reference numerals b and 7c are air communication holes, 8a, 8b and 8c are joints, 9 is a heat dissipation plate, 10 is a communication passage for discharging waste ink, and 11 is a waste ink absorber.

The head chip 1 is arranged in contact with the heat dissipation plate 9. Further, a waste ink absorber 11 is provided on the surface of the heat dissipation plate 9 opposite to the head chip 1.

The head chip 1 has three openings, is connected to the ink flow paths 3a, 3b, 3c, and receives supply of ink of each color. For example, the ink flow path 3a
Supplies cyan ink, the ink flow path 3b supplies magenta ink, and the ink flow path 3c supplies yellow ink. In addition to this, we also supply black ink,
It can be four colors. Of course, the colors are not limited to three colors and four colors, and the ink colors are not limited to the above-mentioned examples.

The head chip 1 is, for example, 300 spi.
The nozzles 2a, 2b, 2c are arranged at a density of (300 DPI), and the above-mentioned three openings are connected to the nozzles 2a, 2b, 2c, respectively. Nozzles 2a, 2
For example, 32 b and 2c can be provided. Between nozzle 2a and nozzle 2b and between nozzle 2b and nozzle 2c
Dummy nozzles 4a and 4b are arranged between them. For example, each of the dummy nozzles 4a and 4b can be provided with 10 nozzles. Dummy nozzles 4a, 4
Dummy nozzle openings 5a and 5b are provided in b. Each figure is illustrated with a number different from the number of nozzles described above for the sake of clarity. However, it goes without saying that the numbers of nozzles and dummy nozzles connected to each opening are not limited to the above-mentioned values, and can be set appropriately.

The three openings provided in the head chip 1 are all separated, so that ink will not mix inside the head chip. The ink flow paths 3a, 3b, 3c are
Ink tank 6 through joints 8a, 8b, 8c
It is connected to a, 6b, and 6c. For example, the ink tank 6a contains cyan, the ink tank 6b contains magenta, and the ink tank 6c contains yellow. In each ink tank, an ink holding material that absorbs and holds ink,
For example, urethane foam, polyester felt, or the like is stored and absorbs and holds each ink.
Further, the ink tanks 6a, 6b, 6c are provided with atmosphere communication holes 7a, 7b, 7c so that the inside of the ink tank does not become a large negative pressure state. Joints 8a, 8
A filter having a particle size of 20 microns, for example, is fused to the tips of b and 8c to remove dust, but it is not shown.

In this embodiment, the number of dummy nozzles 4a and 4b is 10, respectively, and the nozzle 2 for ejecting ink is used.
It is created in the same process as a, 2b, and 2c. Therefore,
Although it also has a heater for generating bubbles, it is not connected to a drive circuit, does not eject ink, and serves as a dummy nozzle. No heater may be provided, and the nozzle 2 that ejects ink
It may be formed with a size different from that of a, 2b, and 2c. Therefore, it does not need to be formed as a dummy nozzle, but it is necessary to be formed as a capillary tube. Dummy nozzle channels 5a and 5b are provided on the opposite sides of the nozzle surfaces of the dummy nozzles 4a and 4b, respectively.
The nozzles 2a, 2b, and 2c are opened on the side of the heat dissipation plate 9 opposite to the side thereof. The dummy nozzle channels 5a and 5b can be formed by anisotropic etching. The anisotropic etching is performed from the surface side of the head chip 1 in contact with the heat dissipation plate 9 so as to spread from the dummy nozzle side toward the heat dissipation plate 9. The dummy nozzle channels 5a and 5b are formed by the same step as the step of forming the nozzle 2 and forming the opening for supplying the ink from the ink channel 3 to the nozzle 2.

The heat dissipation plate 9 has a dummy nozzle channel 5
A communication flow path 10 for discharging waste ink passing through the same position as
Are provided and are connected to the dummy nozzle channel 5. The communication passage 10 for discharging the discharged ink can be formed at the same time when the heat dissipation plate 9 is punched out in the thickness direction by a machine, or can be formed by a drilling process such as a drill.

The waste ink absorber 11 provided on the surface of the heat dissipation plate 9 can be inserted into the communication passage 10 for discharging the waste ink. In addition, the dummy nozzle channel 5
It is also possible to insert the waste ink absorber 11 inside. With such a configuration, the capillary force of the dummy nozzle 4 can be increased, and the ability to suck up the discharged ink mixed on the head surface can be increased. Further, the capillary force of the dummy nozzle 4 can be generated regardless of the size of the dummy nozzle flow path 5 and the communication path 10 for discharging the discharged ink. Further, the waste ink absorber 1 is placed in the dummy nozzle channel 5.
When 1 is inserted, since the dummy nozzle channel 5 is tapered in the direction toward the dummy nozzle 4, the tip of the waste ink absorber 11 is compressed, and the density of the waste ink absorber 11 becomes higher. Therefore, the capillary force can be increased. As a whole, the suction force of the dummy nozzle can be increased.

The waste ink absorber provided in the communication passage 10 for discharging the waste ink and the dummy nozzle flow passage 5 is a heat dissipation plate 9.
It does not have to be integrally formed with the waste ink absorber 11 provided on the surface, and if one surface is in contact with each other, the transfer of the waste ink can be performed smoothly and the function is not impaired. However, the contact surface is compressed,
The higher the density of the discharged ink absorber of the other portion, the better the transferability of the discharged ink.

With this configuration, the nozzles 2a, 2 of different colors are ejected by printing discharge or suction during priming.
The inks discharged from b and 2c and mixed on the head surface are sucked by the dummy nozzle 4 having a capillary force,
It reaches the waste ink absorber 11 through the dummy nozzle flow path 5 and is absorbed. Mixed color ink is dummy nozzle 4
Even when a large amount of ink is generated at one time, which is larger than the capacity of the unnecessary ink or the capacity of the unnecessary ink reservoir, it is absorbed by the waste ink absorber 11 having a capillary force, so that the mixed color ink does not remain on the head surface. It does not affect subsequent printing.

Since the unnecessary ink absorbed by the waste ink absorber 11 is in contact with the atmosphere, the water is evaporated and the waste ink absorber 11 does not always lose its capillary force. Further, since the waste ink absorber 11 is incorporated as a part of the head, it is replaced with the life of the head. Therefore, if the size of the waste ink absorber 11 is set in consideration of the amount of color-mixed ink generated in one head, there is no problem of losing its function due to aging.

Among the mixed color ink sucked up in the dummy nozzle 4 by the capillary force, which remains without being absorbed by the waste ink absorber 11, the dummy nozzle is used when performing the vacuum operation at the time of maintenance. Also, a negative pressure of a vacuum pump (not shown) can be applied and eliminated.

FIG. 4 is an explanatory diagram showing a state during wiping. In the figure, the same parts as those in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted. 12 is a wiper blade,
13a and 13b are ink drops. In this figure, some of the nozzles and dummy nozzles are shown. As described above, unnecessary ink may remain on the head surface when ejecting ink from the nozzle 2 that performs print ejection or when sucking ink from the nozzle 2 by the vacuum operation during priming. If left unattended, the inks will be mixed when the inks of a plurality of colors are used in parallel, which will adversely affect the subsequent print recording.

The wiper blade 12 moves in a direction orthogonal to the nozzle array direction. The wiper blade 12 removes most of the ink droplets 13a and 13b attached to the portions away from the dummy nozzles 4a and 4b, but the nozzles 2a and 2b.
Also spreads in the direction of arrangement. Between the nozzles 2a and 2b of different colors, when the spread ink drops 13a and 13b move to the dummy nozzle 4a, the ink on the nozzle surface is drawn therein by the capillary force of the dummy nozzle 4a. Therefore, the inks of different colors do not touch the nozzles that eject different colors, and the occurrence of color mixture is prevented.

Further, by arranging the end surface of the waste ink absorber 11 attached to the surface of the heat dissipation plate 9 so as to extend to the same surface as the head surface as shown in FIG. The unnecessary ink wiped from the surface of the head is drained by the waste ink absorber 11 at the end of the head.
Therefore, the unnecessary ink adhering to the wiper blade 12 can be removed.

FIG. 5 is an explanatory diagram showing a state during priming. In the figure, the same parts as those in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 14 is a cap, 15 is a suction port, 16a and 16b are drawn inks, and 17 is a mixed color ink. Also in this figure, some of the nozzles and the dummy nozzles are shown. In the priming operation, in order to clear the clogging of the nozzle, the nozzle front face is integrated with the cap 1
4, the suction port 15 of the cap 14 and the dummy nozzle 4
A negative pressure is applied to a. The inks 16a and 16b drawn into the cap from the nozzles 2a and 2b by suction from the suction port 15 of the cap 14 are highly likely to be mixed and mixed.
Is sucked by the dummy nozzle 4a and the suction port 15 and does not remain on the nozzle surface. In particular, since the ink in the intermediate portion of different colors that is most likely to be mixed is quickly sucked and removed from the dummy nozzle 4a, the nozzle 2a or 2b
As a result, no color mixture occurs in the nozzle.

As a comparative example, when the head of the above-described embodiment was used and suction from the dummy nozzle was not performed, color mixing was observed during the priming operation. Furthermore, when a head without dummy nozzles was prototyped and evaluated, color mixing occurred during wiping and color mixing was observed even during normal printing, although it was rare.

[0028]

As is apparent from the above description, according to the present invention, it is possible to provide an integrated type color ink jet print head which effectively prevents color mixture.

Since the nozzles can be arranged on a straight line,
It is not necessary to consider the timing deviation, and printing control is easy. In the case of the logic head, the print data can be controlled by one data line, and the number of connections of the print head can be reduced. Further, since color printing is performed in different print areas for each color, there is also an effect that color bleeding is less likely to occur due to a time lag in color overlapping.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an inkjet printhead of the present invention.

FIG. 2 is a cross-sectional view of a nozzle portion in an embodiment of the inkjet print head of the present invention.

FIG. 3 is a sectional view of a dummy nozzle portion in an embodiment of the inkjet print head of the present invention.

FIG. 4 is an explanatory diagram showing a state during wiping.

FIG. 5 is an explanatory diagram showing a state during priming.

[Explanation of symbols]

1 ... Head chip, 2, 2a, 2b, 2c ... Nozzle,
3, 3a, 3b, 3c ... Ink flow paths, 4, 4a, 4b ...
Dummy nozzle, 5, 5a, 5b ... Dummy nozzle opening, 6
a, 6b, 6c ... Ink tank, 7a, 7b, 7c ... Atmosphere communication hole, 8a, 8b, 8c ... Joint, 9 ... Heat dissipation plate, 10 ... Waste ink discharge communication flow path, 11 ... Waste ink absorber, 12 … Wiper blades, 13a, 13b…
Ink drop, 14 ... Cap, 15 ... Suction port, 16a, 1
6b ... drawn out ink, 17 ... mixed color ink.

Claims (1)

[Claims] 1. In an inkjet printhead in which nozzles for ejecting a plurality of different color inks are arranged in a straight line, nozzles for ejecting a plurality of different color inks are formed, and between the nozzles for ejecting the different color inks. A head chip in which a predetermined number of capillaries are arranged, a heat radiating plate arranged in contact with the head chip and having an ink discharging opening, and provided on the side of the heat radiating plate opposite to the head chip so as to contact the heat radiating plate. An ink jet print head, comprising: a waste ink absorber, wherein the capillary communicates with the ink discharge opening provided in the heat dissipation plate, and further communicates with the waste ink absorber.