JPH08132639A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE: To provide an ink jet recording apparatus preventing the emission inferiority of an ink liquid droplet and reduced in cross talk. CONSTITUTION: A pit groove 4 and a bypass groove 5 are formed to a heater substrate 1 corresponding to each of main passages 3. Grooves 11 for atmosphere communication holes and the atmosphere communication holes 10 corresponding to the main passages 3 are formed to a channel substrate 1 along with a plurality of the main passages 3, communication passages 7 and ink reservoirs 6. A part of the pressure energy of an air bubble generated on a heater 8 propagates to each of the communication passages 7 but the propagated pressure energy is absorbed by the movement of the meniscus of ink formed to each of the atmosphere communication holes 10. Therefore, The pressure energy is prevented from propagating to an adjacent nozzle through each of the communication passages 7 and cross talk can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a plurality of main flow paths each having an energy generating means, and energy is applied to ink in the main flow paths by an energy generating device so that ink is discharged from a nozzle provided at one end of the main flow path. The present invention relates to an inkjet recording device that is ejected as droplets and printed on a recording medium such as paper.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording apparatus has been developed in which energy generating means is provided in a plurality of main flow paths having nozzles at one end, and the other end of each main flow path communicates with a common ink tank reservoir. ing. Examples of the energy generating means include one that converts ink into high-pressure gas by heating the heater to generate energy, and one that energizes the piezoelectric element to deform the piezoelectric element to increase ink pressure in the pressure chamber and generate energy. is there.

In such an ink jet recording apparatus,
The main channel is made as a very fine ink channel.
The ink in the main flow path is held by the capillary force of the meniscus near the nozzle. In addition, even after the droplets fly, the main channel is filled with the ink due to the capillary force. However, since the main channel is minute, dust and bubbles in the ink are likely to be clogged in the main channel, and ink droplets cannot be ejected from the nozzle communicating with the main channel in which dust and bubbles are clogged. There was a failure.

In order to avoid such obstacles, for example,
In Japanese Patent Application No. 5-269899 and the like, a communication flow passage that connects each main flow passage is provided between the energy generating means of the main flow passage and the ink reservoir, and dust or the like is clogged in the communication portion between the main flow passage and the ink reservoir. However, the ink is supplied from the communication flow path to the main flow path to prevent ejection failure.
However, in such a method, the energy generating means provided in the adjacent main flow paths communicate with each other through the communication flow path at a shorter distance than in the past, and the adjacent main flow paths generate energy with each other. There is a phenomenon called crosstalk in which the pressure interferes and the droplet ejection becomes unstable.

Therefore, in Japanese Patent Application No. 5-353106 and the like, a communication flow passage is provided in a bent flow passage portion between the energy generating means and the ink reservoir, and the pressure energy is reflected and interfered to reduce the pressure energy. . FIG. 9 is a sectional view showing an example of a conventional ink jet recording apparatus, FIG.
Similarly, 0 is a plan view. In the figure, 1 is a channel substrate,
Reference numeral 2 is a heater substrate, 3 is a main flow path, 4 is a pit groove, 5 is a bypass groove, 6 is an ink reservoir, 7 is a communication flow path, 8 is a heater, and 9 is a nozzle. The ink jet recording apparatus shown in FIGS. 9 and 10 is configured by bonding the channel substrate 1 and the heater substrate 2 together. The channel substrate 1 is composed of, for example, a silicon wafer, and has a plurality of main flow paths 3,
The communication channel 7 and the ink reservoir 6 that are commonly provided in the main channel 3 are formed by anisotropic etching. The heater substrate 2 is also made of a silicon wafer, and the heater 8 provided corresponding to the plurality of main channels 3 and a heater driving circuit (not shown), wiring, etc. are formed by an LSI process, and a pit is formed by a synthetic resin layer thereon. The groove 4 and the bypass groove 5 that connects the ink reservoir 6 and the communication channel 7 are formed.

In this ink jet recording apparatus, the ink flows like the ink reservoir 6, the bypass groove 5, the communication channel 7, the pit groove 4, and the main channel 3. Bypass groove 5
The depth is shallow, and dust and the like are likely to be clogged at the entrance of the bypass groove 5. However, since the communication channel 7 common to the plurality of main channels is provided, even if dust in the ink of the ink reservoir 6 is clogged in the bypass groove 5, the ink is supplied from the communication channel 7 to the main channel 3, Ink droplets are never jetted out.

Further, when recording, recording is performed by energizing the heater 8 to generate bubbles, and the energy in the bubbles ejects the ink in the main flow path 3 from the nozzles 9. The pit groove 4 has a structure that narrows the flow path behind the heater 8 and efficiently directs the pressure of bubbles formed on the heater 8 toward the nozzle 9. Further, the rear side thereof has a substantially semicircular shape to absorb the pressure wave from the bubbles.

However, the pressure energy of the bubbles generated in the heater 8 propagates to the communication passage 7 and reaches the adjacent main passage via the communication passage 7. Therefore, in the adjacent main flow path, the pressure energy from the heater provided in the main flow path and the pressure wave propagating through the communication flow path 7 interfere with each other, and the ejection becomes unstable. That is, crosstalk will occur. As described above, even with the configurations shown in FIGS. 9 and 10, crosstalk cannot be completely prevented.

Further, in Japanese Patent Application Laid-Open No. 58-136451, the nozzles are divided into a plurality of blocks, and the nozzles in the blocks are sequentially driven so that the time intervals at which the adjacent nozzles in each block are driven become long. By doing so, crosstalk is prevented. However, since the nozzles in the block are sequentially driven, there is a problem that unless the drive timing is adjusted, the dot position varies in the direction perpendicular to the nozzle row, and the deterioration of image quality becomes noticeable.

In addition, the XEROX DISCLOSUR
E JOURNAL, Vol. 16, No. 4, p. Two
According to Nos. 21 to 225, an air chamber in which air bubbles are trapped is provided in the flow path, the heater is driven with a long drive pulse or a high drive voltage or a fast drive frequency, and air bubbles are trapped in the air chamber. Using bubbles as dampers,
It is trying to help prevent crosstalk and promote ink supply. However, the print head shown in this document does not have a communication passage for avoiding clogging of the nozzle due to dust or the like.

Further, for example, Japanese Patent Laid-Open No. 55-128465.
In Japanese Patent Laid-Open No. 59-138461, etc., an air communication hole other than a nozzle is provided in the flow passage to remove bubbles in the flow passage. These techniques are not techniques for suppressing crosstalk, and a configuration for avoiding nozzle clogging due to dust or the like is not shown.

[0012] For example, in Japanese Patent Laid-Open No. 62-111756, through holes are provided on both sides of the nozzle in parallel with the nozzle to communicate with the atmosphere to prevent acoustic influence between the nozzles, and to vibrate meniscus after the droplet ejection. Is rapidly decaying. In this technique, since it is necessary to provide through holes between the nozzles, it is not possible to increase the nozzle array density,
It is not possible to cope with the recent increase in density. Further, since the pressure at the time of ejecting the ink directly acts on the through hole, the generated pressure cannot be effectively used, and there is a problem that energy efficiency is poor. Further, this document also does not describe a configuration for avoiding clogging of the nozzle due to dust or the like.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and prevents defective ejection of ink droplets due to dust in the ink clogging the main flow path and reduces crosstalk. It is an object of the present invention to provide an inkjet recording device.

[0014]

According to a first aspect of the present invention, there is provided a plurality of main flow passages each having a nozzle at one end, and energy generating means arranged corresponding to each main flow passage. In an ink jet recording apparatus having a common ink reservoir that communicates with each of the main channels, a communication channel for communicating the main channels is provided between the energy generating unit and the ink reservoir, and the communication channel further includes an atmosphere. It is characterized in that a communication hole opened to the inside is provided.

In the invention described in claim 2,
An ink jet recording apparatus having a plurality of main flow paths having nozzles at one end, energy generating means arranged corresponding to the respective main flow paths, and a common ink reservoir communicating with the respective main flow paths, the energy generating means A communication channel for communicating the main channels, a sealed air chamber, and a communication hole connecting the communication channel and the air chamber are provided between the ink reservoir and the ink reservoir.

The communication hole can be provided corresponding to each of the main flow paths as in the invention according to the third aspect.
Alternatively, as in the invention described in claim 4, the main flow path can be divided into several blocks, and the communication holes can be provided corresponding to each block.

[0017]

The energy generated by the energy generating means in the main flow path is propagated in the nozzle direction and is used for ejecting ink droplets, and the energy is propagated in the communication flow path direction and is divided into components causing crosstalk. . According to the present invention, the pressure energy propagating in the direction of the communication channel that causes crosstalk is communicated with the communication hole or the air chamber that communicates with the atmosphere before propagating to the adjacent main channel via the communication channel. It is consumed by the vibration of the ink meniscus in the holes. As a result, the energy propagating to the adjacent nozzles can be suppressed, the crosstalk phenomenon can be reduced, and the liquid droplets can be ejected more stably, and high image quality and high speed of the inkjet recording apparatus can be realized. it can. When the communication hole communicates with the closed air chamber and is shielded from the atmosphere, the ink can be prevented from evaporating from the communication hole.

By providing the communication hole corresponding to each main flow path as in the invention described in claim 3, it is possible to absorb the pressure energy generated in any of the main flow paths.
The influence on other nozzles can be reduced. Further, when the nozzles are divided into blocks and each block is sequentially driven, as in the invention according to claim 4, by providing a communication hole corresponding to each block, it is generated in each block that is sequentially driven. It is possible to absorb the pressure energy that occurs and reduce the influence on different blocks.

[0019]

1 is a sectional view showing a first embodiment of an ink jet recording apparatus of the present invention, and FIG. 2 is a plan view of the same. In the figure, parts similar to those in FIGS. 9 and 10 are designated by the same reference numerals, and description thereof will be omitted. Reference numeral 10 is an atmosphere communication hole, and 11 is a groove for the atmosphere communication hole. In FIG. 2, the hatched portion to the right indicates the unetched portion of the channel substrate 1. The pit groove 4 and the bypass groove 5 provided on the heater substrate 1 are indicated by broken lines.

The channel substrate 1 is composed of a silicon wafer, and is provided with a main flow path 3, a communication flow path 7, an ink reservoir 6, an air communication hole groove 11, and an atmosphere communication hole 10 corresponding to the main flow path 3. ing. Atmosphere communication hole groove 11
Is provided in parallel with the communication channel 7, and is formed by anisotropic etching from the back surface with respect to the surface on which the main channel 3 and the like are formed. After forming the groove 11 for the atmosphere communication hole, the atmosphere communication hole 10 is formed by the ion beam method or the like to form the channel substrate 1. The heater substrate 1 has the same structure as the conventional structure shown in FIGS. 9 and 10, and the heater 8 and common electrodes, individual electrodes, drive circuits and the like (not shown) are formed on a silicon wafer by an LSI process, and a synthetic resin is formed thereon. The layer forms a pit groove 4 and a bypass groove 5 that connects the ink reservoir 6 and the communication channel 7. These pit groove 4 and bypass groove 5 are provided corresponding to each main flow path 3.

The ink is supplied from the ink reservoir 6 to the main flow path 3 through the bypass groove 5, the communication flow path 7 and the pit groove 4. Since the bypass groove 5 formed in the synthetic resin layer is shallow, dust or the like that has entered the ink reservoir 6 is collected at the entrance portion of the bypass groove 5. Further, dust and the like that have passed therethrough can be collected at the connecting portion between the bypass groove 5 and the communication channel 7. The dust or the like that has passed through this portion is discharged from the nozzle 9 as the ink is ejected, so that the image quality failure due to the nozzle clogging does not occur. When dust or the like is collected at the inlet or the outlet of the bypass groove 5, the ink flow in the bypass groove 5 becomes poor, or the ink does not flow. However, the bypass groove 5 is full of dust
The ink introduced from the other bypass groove is supplied to the main flow path 3 corresponding to (1) through the communication flow path 7. for that reason,
No ejection failure occurs and image quality failure is avoided.

During recording, the heater 8 generates heat and bubbles are generated on the heater 8. Then, due to the pressure when the bubbles expand, the ink in the main flow path 3 is ejected from the nozzles 9 and landed on the recording medium, and recording is performed. The expansion of the bubbles is controlled by the side surface of the pit groove 4 on the nozzle 9 side, the two side surfaces of the main flow path 3 in the arrangement direction, and the constricted portion on the communication flow path 7 side. Moreover, the propagation of pressure in the direction of the nozzle 9 is promoted by the inclined surface at the inner part of the main flow path 3. However, the pressure energy of the bubbles is
After passing through the constricted portion, it further propagates in the direction of the communication flow path 7. A portion of the pit groove 4 collides with the side wall of the connection portion with the communication flow path 7. Since the connection portion of the pit groove 4 with the communication channel 7 is formed in a substantially semicircular shape, the pressure energy is diffusely reflected and attenuated in this portion. In addition, a part of the pressure energy propagates to the communication flow path 7. The pressure energy propagated to the communication passage 7 is mainly from the pit groove 4 to the communication passage 7.
Has a directional component to, and propagates to the atmosphere communication hole 10 by going straight as it is. An ink meniscus is formed in the atmosphere communication hole 10, and the pressure energy is attenuated as the ink meniscus moves in the atmosphere communication hole 10. In this way, the pressure energy propagated in the communication flow path 7 is transferred to the atmosphere communication hole 10
Can be attenuated and the propagation to other main flow paths can be reduced. This can prevent crosstalk.

FIG. 3 is an explanatory diagram of an example of a driving method in the first embodiment of the ink jet recording apparatus of the present invention. In the figure, 3 is a main flow path, 12 is an ink droplet, and 13 is a block. In the driving method shown in FIG. 3, a plurality of nozzles adjacent to each other are set as a block 13, and the nozzles in the block are driven at the same time to eject ink droplets 12 for recording. Further, each block is sequentially driven from one end. For example, 12
Eight nozzles arranged in a row are divided into blocks 13 for every four adjacent nozzles. Then, each block 13
The four nozzles included in (1) are driven simultaneously, and one block is driven sequentially from the end block. The drive time difference between adjacent blocks can be set to, for example, about 3.25 μsec.

When such a driving method is used, the nozzle adjacent to the block boundary, that is, the nozzle indicated by the arrow in FIG. 3, is most susceptible to the crosstalk.
When the pressure energy generated by the drive of the immediately preceding block propagates to the adjacent nozzle immediately before the drive, the state of the meniscus of the nozzle changes, and the ejection of ink droplets tends to become unstable. In the conventional ink jet recording apparatus, an image quality defect appears in the image recorded on the recording medium due to the influence of crosstalk. In the present invention, such propagation of pressure energy to the adjacent nozzles is absorbed by the atmosphere communication hole 10 to prevent the influence of crosstalk.

FIG. 4 is an explanatory diagram of a comparison result between the ink jet recording apparatus of the present invention and the conventional ink jet recording apparatus. Here, as the inkjet recording apparatus of the present invention, three types of inkjet recording apparatuses having different flow path resistances of the atmosphere communication holes 10 were used for the experiment. Atmosphere communication hole 10
Is too large, it becomes impossible to retain the ink due to the capillary force. On the other hand, if it is too small, the flow path resistance increases, and the pressure energy cannot be attenuated at this portion, and the pressure energy propagates to the adjacent nozzle. Therefore, it is necessary to pay attention to the cross-sectional area and length of the atmosphere communication hole. Here, when the ratio of the flow path resistance of the atmosphere communication hole to the flow path resistance of the other main flow path is 5: 4, 1: 1 and 3: 4.
The case was tested.

In the experiment, a solid image was printed by ejecting all the nozzles, and the highest driving frequency at which an image having no image quality defect could be printed was obtained. As a result, the maximum driving frequency could be increased in any case with the inkjet recording apparatus of the present invention as compared with the conventional inkjet recording apparatus. As described above, in the ink jet recording apparatus of the present invention, the crosstalk can be reduced by the atmosphere communication hole, so that an image having no image quality defect can be obtained even if the driving frequency is increased. Also, the maximum driving frequency is higher when the flow path resistance of the atmosphere communication hole is smaller.
The smaller the flow path resistance of the atmosphere communication hole, the higher the ability to absorb the pressure energy, and further the crosstalk can be reduced. As a result, it is possible to obtain an image having no image quality defect even at a high driving frequency, and it is possible to achieve high speed and high image quality of the inkjet recording apparatus.

Further, the illumination was made to emit light in synchronization with the frequency of ejecting ink droplets, the ink jet recording apparatus was driven at a high driving frequency, and the shape of flying droplets was observed.
According to the observation, in the conventional inkjet recording apparatus, the ejection was unstable, whereas in the inkjet recording apparatus using the embodiment of the present invention, the ejection was stable, and as a result, the image quality defect was eliminated. Was confirmed.

FIG. 5 is a plan view showing a second embodiment of the ink jet recording apparatus of the present invention. Reference numerals in the figure are the same as those in FIGS. Reference numerals 14 and 15 are blocks.
In this embodiment, an example is shown in which the atmosphere communication hole 10 is provided corresponding to each of the blocks 14 and 15 when the block drive is performed as shown in FIG. As described above, the nozzle adjacent to the previously driven block, for example, the nozzle indicated by the arrow in FIG. 3, is most susceptible to the crosstalk. From this, it is effective to provide the atmosphere communication hole corresponding to the nozzle adjacent to the block to be driven next that is most likely to be affected by crosstalk. In the example shown in FIG. 3, four nozzles are used as one block. Therefore, in order to reduce the pressure propagation from the nozzle driven first in the 4n + 1th main flow channel, the 4nth main flow channel is supported. An atmosphere communication hole may be provided. Here, n is a natural number. In FIG. 5, block 14 is driven first,
The upper block 15 is then driven. Block 1
An atmosphere communication hole 10 is provided corresponding to the nozzle adjacent to the block 15 in the nozzle 4. Also in the block 15, the atmosphere communication hole 10 is provided at the same position. By providing the atmosphere communication hole 10 at such a position, it is possible to stabilize the injection in the main flow path most susceptible to the crosstalk. Further, in such a configuration, since the number of atmosphere communication holes is the number of blocks, it is possible to reduce the number of processing steps for manufacturing the atmosphere communication holes.

FIG. 6 is a plan view showing a third embodiment of the ink jet recording apparatus of the present invention. Reference numerals in the drawings are the same as those in FIGS. 1, 2 and 5. In this embodiment, the atmosphere communication hole 10 is formed in a slit shape. Even with such a slit-shaped atmosphere communication hole 10, a meniscus due to the capillary force of ink can be formed in the slit by adjusting the width of the slit, and the pressure energy is reduced by the movement of this meniscus. It is possible. In FIG. 6, a slit-shaped air communication hole 10 is provided for each block. Besides this, all the main flow paths 3
Various modifications are possible such as common to all the blocks or only to a part of the block.

FIG. 7 is a sectional view showing a fourth embodiment of the ink jet recording apparatus of the present invention, and FIG. 8 is a plan view of the same. In the figure, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 21 is an air chamber, and 22 is an ink tank. In FIG. 8, the joint surface between the channel substrate 1 and the ink tank is hatched. Further, the flow paths formed in the heater substrate 2 are shown by broken lines.

In this embodiment, an example is shown in which the air communication hole groove 11 shown in FIG. 1 is sealed to form an air chamber 21 which is isolated from the atmosphere. As a result, the atmosphere communication hole 10 communicates with the air chamber 21 that is closed. Here, the pressure in the air chamber 21 may be approximately the same as the atmospheric pressure. In the configuration shown in each of the above-described embodiments, one end of the atmosphere communication hole 10 is open to the atmosphere, so that the ink evaporates from the atmosphere communication hole 10. In this embodiment, the atmosphere communication hole 1
By connecting 0 to the air chamber 21 that is shielded from the atmosphere, the ink can be prevented from evaporating in the atmosphere. Figure 7
In the example shown in, the ink chamber 22 arranged on the channel substrate 1 constitutes the air chamber 21 that is hermetically sealed. Of course, the structure for forming the air chamber 21 is arbitrary. The ink tank 22 holds ink and supplies the ink to the ink reservoir 6.

Also in the fourth embodiment, it is possible to carry out the block drive as described in FIG. 3 and provide the atmosphere communication hole 10 for each block as shown in FIG. 5 and FIG. .

[0033]

As is apparent from the above description, according to the present invention, by providing the communication passage and the atmosphere communication hole corresponding to the main passage or the drive block in the communication passage, dust is generated. There is an effect that the ejection failure of the nozzle can be eliminated, the instability of the ink droplet due to the crosstalk can be suppressed, and the high image quality and the high speed can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an inkjet recording apparatus of the present invention.

FIG. 2 is a plan view showing a first embodiment of the inkjet recording apparatus of the present invention.

FIG. 3 is an explanatory diagram showing an example of a driving method in the first embodiment of the inkjet recording apparatus of the present invention.

FIG. 4 is an explanatory diagram of a comparison result between the inkjet recording apparatus of the present invention and a conventional inkjet recording apparatus.

FIG. 5 is a plan view showing a second embodiment of the inkjet recording apparatus of the present invention.

FIG. 6 is a plan view showing a third embodiment of the inkjet recording apparatus of the present invention.

FIG. 7 is a cross-sectional view showing a fourth embodiment of the inkjet recording apparatus of the present invention.

FIG. 8 is a plan view showing a fourth embodiment of the inkjet recording apparatus of the present invention.

FIG. 9 is a sectional view showing an example of a conventional inkjet recording apparatus.

FIG. 10 is a plan view showing an example of a conventional inkjet recording apparatus.

[Explanation of symbols]

1 ... Channel substrate, 2 ... Heater substrate, 3 ... Main channel, 4 ...
Pit groove, 5 ... Bypass groove, 6 ... Ink reservoir, 7 ...
Communication channel, 8 ... Heater, 9 ... Nozzle, 10 ... Atmosphere communication hole, 11 ... Atmosphere communication hole groove, 12 ... Ink droplet, 13 to 1
5 ... Block, 21 ... Air chamber, 22 ... Ink tank.

Claims (4)

[Claims] 1. A plurality of main channels having a nozzle at one end,
In an ink jet recording apparatus having an energy generating unit arranged corresponding to each main flow channel and a common ink reservoir communicating with each main flow channel, each main flow channel is provided between the energy generating unit and the ink reservoir. An ink jet recording apparatus, characterized in that a communication flow path for communication is provided, and further a communication hole open to the atmosphere is provided in the communication flow path. 2. A plurality of main channels having a nozzle at one end,
In an ink jet recording apparatus having an energy generating unit arranged corresponding to each main flow channel and a common ink reservoir communicating with each main flow channel, each main flow channel is provided between the energy generating unit and the ink reservoir. An ink jet recording apparatus, comprising: a communication channel for communication, a sealed air chamber, and a communication hole connecting the communication channel and the air chamber. 3. The ink jet recording apparatus according to claim 1, wherein the communication hole is provided corresponding to each of the main flow paths. 4. The ink jet recording apparatus according to claim 1, wherein the main flow path is divided into some blocks, and the communication holes are provided corresponding to each block.