JPH0557894A - Ink jet recording head and restoration of clogging thereof - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to a mechanism for recovering from clogging of an inkjet recording head, which is capable of eliminating a completely clogged state of a nozzle hole due to solidification and deposition of an ink solute such as a dye. The purpose is to provide a mechanism for recovering from clogging. The inkjet recording head 10 includes an ink flow path 1 to which ink is supplied, and nozzles 2 ₁ to 2 ₄ communicating with the ink flow path 1 and opening in a nozzle surface 4. The nozzles 2 ₁ to 2 Recording is performed by ejecting or drawing the ink from ₄ to the recording medium. The recording head 10 includes a dummy nozzle 3 larger opening than the nozzle 2 ₁ to 2 ₄ to the nozzle surface 4, and the ink flow path 5 for the dummy nozzles communicating to the dummy nozzle 3 is provided. In the clogging recovery, decomposed with ink discharged from the dummy nozzles 3, covers the nozzle 2 ₁ to 2 ₂ clogged, solidification causing the clogging, precipitates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head clogging recovery mechanism.

The ink jet recording system has a high quietness and has been attracting attention especially in recent years. However, there is a problem that when the ink solvent evaporates, the dye precipitates and solidifies to clog the nozzle holes. That is, in the ink jet recording head, since minute nozzles are used, precipitation and solidification at the nozzle portion are remarkable, which is the biggest problem that hinders improvement in reliability of the apparatus.

[0003]

2. Description of the Related Art In a conventional ink jet recording head clogging recovery mechanism, there is a method of pressurizing or sucking ink, and removing the deposited and solidified dye clogging the nozzle with the flow of ink by this pressure. Was used. According to this method, when the nozzle hole is partially clogged, the ink is discharged from the non-clogging portion of the nozzle opening due to pressurization or suction, and thus, It is possible to remove the solidified and precipitated dyes that cause the clogging.

[0004]

However, in this method, when the nozzle hole is completely clogged, it may be difficult to flow the ink from the nozzle even if the nozzle hole is pressed or sucked with a considerably high pressure. In many cases, it was not possible to restore the printable state.

The present invention is directed to solidifying ink solutes such as dyes,
An object of the present invention is to provide a mechanism for recovering the clogging of an ink jet recording head, which can eliminate a completely clogged state of a nozzle hole due to deposition.

[0006]

In order to achieve the above-mentioned object, in the present invention, an ink flow path for receiving ink supply,
An ink jet recording head, comprising: a nozzle communicating with the ink flow path and having an opening on a nozzle surface, for performing recording by ejecting or drawing ink from the nozzle to a recording medium, and a dummy having an opening larger than the nozzle on the nozzle surface. In addition to forming the nozzles, a dummy nozzle ink flow path communicating with the dummy nozzles is provided (first configuration).

Further, in the ink jet recording head according to the first aspect, when the maximum dye dissolution amount of the ink solvent is A, an ink satisfying the dye amount a <A is used for recording (second aspect). Configuration).

Further, in the ink jet recording head according to the first aspect, the nozzles clogged with the ink discharged from the dummy nozzles are covered, and the solidification and deposits causing the clogging are decomposed to restore the printable state. The configuration (third configuration) is characterized in that

[0009]

The clogging due to solidification and precipitation is less likely to occur as the nozzle opening area is larger, and the solidification and precipitation is easily decomposed when in contact with ink. In view of this, the present invention provides the nozzle surface with a dummy nozzle that does not contribute to printing of an opening larger than the nozzle that contributes to printing. Since the ink in the dummy nozzle has a large opening, the ink in other minute nozzles for printing solidifies and does not solidify even if clogging occurs. Therefore, the ink can be discharged from the dummy nozzle by sucking the ink from the nozzle surface or pressurizing the ink from the ink supply port. Then, the ink discharged from the dummy nozzle covers the nozzle surface, so that the deposits and solidified substances that have clogged the printing minute nozzles come into contact with the ink and decompose. As a result, ink can be discharged from the printing minute nozzles by ink suction from the nozzle surface and pressurization of ink from the ink supply port, thereby eliminating clogging and restoring the printable state.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an ink jet recording head 1 of this example.
In the figure, 1 is a plurality of (for example, 4
Ink flow paths 2 ₁ , 2 ₂ , 2 ₃ and 2 ₄ branching into (main) nozzles having minute openings that contribute to printing (ink is ejected or drawn out based on print data),
Reference numeral 3 is a dummy nozzle having a large opening that does not contribute to printing.

The ink flow path 1 is supplied with ink from an ink cassette (not shown) through an ink supply port 6. Each of the nozzles 2 ₁ , 2 ₂ , 2 ₃ and 2 ₄ has an ink channel 1 at one end.
Communicates with each branch portion of the nozzle and the other end is open to the nozzle surface 4. The dummy nozzle 3 has a larger diameter than the nozzles 2 ₁ to _{2 2} .
The ink flow path 1 has one end through the ink flow path 5 for the dummy nozzle.
Communicating with the other end is largely opened from the nozzle _{21 to 24} to the nozzle surface 4.

As described above, the dummy nozzle 3 is connected to the nozzle 2 ₁
Because it has an opening area larger than 21 to _24, deposition of a dye such as ink solute content than these nozzles 2 ₁ to 2 _4,
Clogging due to solidification is less likely to occur (the larger the nozzle opening area, the less likely clogging occurs). Therefore,
Nozzles 2 ₁ to 2 ₄ are deposited, be completely clogged by solidification, the dummy nozzle 3 not fully clogged,
The ink can be easily discharged.

Therefore, the ink can be discharged from the dummy nozzle 3 by sucking the ink from the nozzle surface or pressurizing the ink from the ink supply port 6. Then, the ink ejected from the dummy nozzles 3 covers the nozzle surface 4 so that the nozzles 2 ₁ to 2 ₄
The deposits and solidified substances that had clogged the ink come into contact with the ink and decompose. Thus, the pressure of the ink from the suction and the ink supply port 6 of the ink from the nozzle surface 4, the nozzles 2 ₁ to
2 ink is ejected clogging is eliminated from _4, it can be restored to a printable state.

FIG. 2 shows the relationship between the nozzle opening area and the clogging time due to complete precipitation and solidification. In this case, the composition of the ink is 5% by weight of dye, 10% by weight of diethylene glycol and 85% by weight of water, and the environment is an air temperature of 23 to 25 ° C. and a relative humidity of 40 to 60%.

In the above description, the ink discharged from the dummy nozzle leaks and spreads over the nozzle surface, so that the nozzle surface is covered with ink. However, when the nozzle surface is difficult to leak with ink, it becomes difficult to cover it. Therefore, when the nozzle surface is not perpendicular to the moving direction, the dummy nozzle is provided on the upper part. As a result, the ink discharged from the dummy nozzles flows on the nozzle surface, and the clogging nozzle openings located below can be brought into contact with the ink. This operation will be specifically described with reference to FIG.

FIG. 3 shows the operation when the nozzle surface is parallel to the direction of gravity (clogging recovery process).
3 (A) is a clogging of the nozzles 2 ₁ to 2 _4, 3
3B shows the discharge state of the ink from the dummy nozzle 3, FIG. 3C shows the state of precipitation and decomposition of the solidified matter, and FIG. 3D shows the state of recovery. As is clear from FIG. 3C, the decomposed precipitates and solidified substances are removed from the nozzle surface 4 by riding on the ink flow.

By the way, the ink jet recording head is
The types of clogging include not only the cause of the present invention, which is the precipitation and solidification of the ink solute by evaporation of the ink solvent, but also the presence of air bubbles in the ink flow path. If bubbles exist in the flow path, the bubbles absorb the energy that ejects ink from the nozzles, and recording cannot be performed.

The bubbles in the ink flow path are discharged to the outside together with the ink flow when the ink is discharged from the nozzles. In the head having the dummy nozzle of the present invention, the ink is discharged from the dummy nozzles. It is effective to discharge air bubbles by reducing the amount of ink discharged from the nozzle that contributes to printing, and there is an advantage that ink consumption is small. To reduce the ink discharge, it is possible to increase the resistance of the ink flow path.

Therefore, the fluid resistance R of the ink flow path for the dummy nozzle may be set so as to satisfy R ≧ r with respect to the fluid resistance r of the ink flow path of the nozzle that contributes to printing. In order to realize this, it is effective to provide a diaphragm in the middle of the ink flow path for the dummy nozzle or increase the flow path length. FIG. 4 shows the relationship between the fluid resistance ratio R / r and the bubble discharge rate (restorability). The upper curve is the discharge operation time 30s
And the lower curve shows the case where the discharge operation time is 5 s.

To increase the fluid resistance of the ink flow path,
As described above, it is effective to provide a diaphragm in the ink flow path or increase the flow path length. However, if the flow path near the nozzle hole is provided with a throttle or the like to increase the resistance, the ink concentrated by evaporation in the vicinity of the nozzle hole becomes difficult to disperse, and precipitation and solidification are likely to occur. Therefore, it is suitable to provide a diaphragm or the like to increase the resistance, as far as possible from the nozzle hole.

Therefore, as shown in FIG. 5, the narrowed portion 5 is located at the farthest position from the nozzle hole of the ink passage for the dummy nozzle.
It is desirable to provide a.

Further, according to the present invention, it is necessary to bring the ink discharged from the dummy nozzle into contact with the deposited or solidified material of the clogged nozzle. As a result, the precipitate and solidified substance are decomposed. Usually, the time required for the decomposition is about several seconds, but the longer the contact time is, the more the decomposition is promoted and the larger the effect is. In order to keep the contact time long, it is necessary for the ink to be easily retained on the nozzle surface.

Therefore, FIG. 6 (FIG. 6A is a plan view of the recording head, FIG. 6B is a view taken in the direction of arrow A in FIG. 6A), and FIG.
6C, it is effective to form the concave portion 7 in the nozzle row portion of the nozzle surface, as shown in the arrow B view of FIG. 6A. This makes it easier for ink to accumulate in the recess 7,
It is possible to keep the contact time long.

Further, the precipitation and the solidified matter are brought into contact with the ink and decomposed by the dissolving action. Therefore, the more the ink has the ability to dissolve the dye, the more the decomposition is promoted. Almost all dyes precipitate and solidify by evaporation (there are also trace impurities such as inorganic salts). Therefore, the dye dissolution amount a of ink
However, the smaller the maximum dye dissolution amount A of the ink, the faster the precipitation and decomposition of the solidified matter, and the faster the recovery to the printable state. FIG. 7 shows the relationship between a / A and the number of ink discharge operations until recovery.

As described above, it is necessary to hold the ink discharged from the dummy nozzles on the nozzle surface, but after the deposition and the solidified material are decomposed, the ink held on the nozzle surface is ejected or ejected. It must be removed so that it does not interfere with the drawer. This enables stable printing operation. An example of specific means for this will be described with reference to FIG.

The ink discharged from the dummy nozzle 3 is
As shown in FIG. 8A, the nozzle surface 4 is covered and held in that state. Thereafter precipitation nozzles 2 ₁ to 2 ₄ were clog eyes, when the solidified product was decomposed, FIG from the position shown in FIG. 8 (A) as the absorber 8 contacts the lower portion of the nozzle surface 4 1 (B ) Comes to the position. As a result, the ink held on the nozzle surface 4 is absorbed by the absorber 8 and removed from the nozzle surface 4 as shown in FIG. 8C. The absorber 8 then returns to a position away from the nozzle surface 4.

FIG. 8 shows an example in which the absorber 8 moves to a lower portion of the nozzle surface 4, but the absorber is fixed and the head is moved toward the absorber to absorb the nozzle surface. You may make it contact with the body. Further, for removing ink, instead of the absorber, a method may be adopted in which a suction port is provided close to the lower portion of the nozzle surface to suck the ink, a method in which an air nozzle is provided to blow the ink away, and the like.

[0029]

As described above, according to the present invention, it is possible to eliminate the complete clogging of the nozzle holes due to the solidification and precipitation of the ink solute such as dye, and it is possible to improve the reliability. become.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating the structure of an inkjet recording head according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating the relationship between the nozzle opening area and the clogging time according to the embodiment of this invention.

FIG. 3 is an explanatory diagram of a clogging recovery process according to an embodiment of the present invention.
3A shows a clogging state, FIG. 3B shows a state of discharging ink from a dummy nozzle, FIG. 3C shows a state of precipitation and decomposition of solidified matter, and FIG. 3D shows a state of recovery. , Respectively.

FIG. 4 is a diagram illustrating a relationship between a flow path resistance ratio and a bubble discharging property according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of the shape of the ink flow path for the dummy nozzle according to the embodiment of the present invention.

6A and 6B are explanatory views showing an example of the shape of a nozzle surface of an ink jet recording head according to an embodiment of the present invention, FIG. 6A is a plan view of the recording head, and FIG. 6B is a view taken along an arrow A in FIG. 6A. Figure, Figure 6
6C is a view on arrow B of FIG.

FIG. 7 is a diagram illustrating the relationship between dye solubility and recoverability of the ink according to the embodiment of the present invention.

8A and 8B are explanatory views of a procedure for holding and removing ink on a nozzle surface according to an embodiment of the present invention. FIG. 8A shows a state of discharging and holding ink, and FIG. 8B shows a state of precipitation and decomposition of solidified matter. FIG. 8C shows the state of movement of the absorber, and the state of ink suction and removal.

[Explanation of symbols]

1 Ink flow path 2 ₁ , 2 ₂ , 2 ₃ , 2 ₄ nozzle 3 Dummy nozzle 4 Nozzle surface 5 Ink flow path for dummy nozzle 10 Inkjet recording head

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B41J 2/175 2/135 8703-2C B41J 3/04 102 Z 9012-2C 103 N

Claims (3)

[Claims] 1. An ink flow path (1) for receiving ink supply
When, and a nozzle (21 _{to 24)} which opens in communication with the nozzle surface (4) in the ink flow path (1), the nozzle (2 ₁ -
Formed in 2 ₄₎ an ink jet recording head for recording by the ink jet or be drawn into the recording medium than in the nozzle surface (4), a dummy nozzle (3) for larger opening than said nozzle _{(21 to 24)} In addition, the ink jet recording head is characterized in that an ink flow path (5) for a dummy nozzle is provided so as to communicate with the dummy nozzle (3). 2. The ink jet recording head according to claim 1, wherein an ink satisfying a dye amount a <A is used for recording, where A is the maximum dye dissolution amount of the ink solvent. 3. The ink jet recording head according to claim 1, wherein the nozzles (2 ₁ to 2 ₄ ) clogged with the ink discharged from the dummy nozzle (3) are covered, and solidification and deposition that cause the clogging. A method for recovering from clogging of an ink jet recording head, which is characterized by disassembling an object to recover a printable state.