JPS61195850A - Clogging prevention device for ink jet recording head - Google Patents

Abstract

PURPOSE:To prevent clogging of an ink jet recording head by adhering a continuous gas-permeable porous member impregnated with low volatility solvent on the outer side of a small aperture for spraying ink droplets and sealing them together. CONSTITUTION:If a recording head 10 stops facing a capping head 30, a small aperture in a plate-like member 14 located at the tip of the recording head 10 adheres to a projection 32a of a porous member 32 exposed from a case 31 of the capping head 30 and is hermetically sealed by the porous member 32 and low volatility solvent impregnated in the porous member 32. That is, the evaporation of liquid ink 11 in the recording head 10 through the small aperture 17 is prevented by the blocking of the small aperture 17 by adhering porous member 32 impregnated with low volatility solvent. Thus the clogging of the small aperture with ink can be prevented because ink evaporation is prevented during the non-recording by an ink jet recording head.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a clogging prevention device for an inkjet recording head, and more specifically, to a clogging prevention device for an inkjet recording head, and more specifically, a device for preventing clogging of an inkjet recording head, in which a small opening of a nozzle or the like that forms ink droplets of an inkjet recording head is used to prevent clogging of the ink. This invention relates to a device for preventing clogging.

(Prior Art) Inkjet printers that record on recording paper by ejecting ink droplets from small openings such as small-diameter nozzles or orifices are well known. In inkjet printers, solid components of liquid ink tend to stick to small openings and cause clogging. As a device for preventing nozzle clogging, there is a well-known marking device in which the tip of a marking ink nozzle is sealed with a sealing liquid, as shown in FIG. .・6) No. 77). That is, in the marking device shown in FIG. 5, when the marking liquid 2 is force-fed into the nozzle container l from the direction of arrow a.

The marking liquid 2 is ejected from the nozzle la to mark a member to be marked (not shown).

After the marking is completed, the sealing liquid 4 is introduced from the direction indicated by the arrow into the supply path 3a formed in the outer case 3, and the sealing liquid 4 filling the liquid reservoir 3b around the nozzle 1a is applied to the tip of the nozzle 1a by capillary action. It fills the cylindrical portion 3c. Since the sealing liquid 4 is compatible with the marking liquid 2 and has low volatility, the tip of the nozzle 1a is stably sealed for a long period of time. When reusing, the sealing liquid 4 is removed by jetting out the marking liquid 2 and marking is performed.

However, the above-mentioned marking device is designed to mark relatively large members such as steel materials, and is large in size and targets four nozzles.
Therefore, processing is complicated and difficult to implement in a recording head such as an inkjet printer's recording head, which is small and delicate and is desired to be multi-purpose. Furthermore, there are various configurations of inkjet recording heads, and the method of guiding the sealing liquid to the nozzle tips as described above is not necessarily applicable in general.

(Objective) In view of the above-mentioned points, an object of the present invention is to provide a wide range of application, a simple structure, excellent maintainability, and reliable visibility without affecting the structure of an inkjet recording head. To provide a clogging prevention device for an inkjet recording head that can prevent clogging.

(Summary) The clogging prevention device for an inkjet recording head of the present invention uses a continuous air permeable flexible porous member impregnated with a low-volatile solvent to fly ink droplets from the inkjet recording head at a non-recording position. The small opening is sealed from the outside by being brought into close contact with the small opening.

(Example) Hereinafter, the present invention will be explained with reference to illustrated embodiments.

An embodiment of an inkjet printer to which the clogging prevention device of the present invention is applied is constructed as shown in FIG. xi, 2. In the inkjet printer shown in both figures, an inkjet recording head 1o is constructed by holding a heating element head 13 and a plate-like member 14, which is a small opening forming member, in a housing 12 that accommodates liquid ink 11. There is. That is, the front part of the recording head 10u and the heat generating head 13 are inserted through the housing 12 and accommodated in the lower ink chamber 15, and the heat generating part 16 (the first On the other hand, a plate-like member 14' having a small opening 17 (see Fig. 3) facing the open front surface of the housing 12, The plate member 14 is arranged to face the heat generating part 16 through a minute gap 18 (see FIG. 3) of, for example, 0 to 100 microns.

A lower ink chamber 15 and an upper ink chamber 19 of the housing 12 are filled with liquid ink 11. For this reason,
The small opening 17 and the gap 18 are filled with liquid ink 11. Note that the small opening 17 may not be filled with the liquid ink 11 all the time. Lower ink chamber 1
The upper plate of the housing 12 forming an upper ink chamber 19 having a larger volume than that of the ink chamber 5 is provided with air for introducing air corresponding to the amount of ink 11 consumed to maintain the pressure inside the ink chamber at atmospheric pressure. A small hole 20 is formed. The rear part of the heating element head 13 passes through the housing 12 and projects out of the ink chamber 15 in order to apply a recording signal.

Note that the heat generating section 16 of the heat generating head 13 may be configured to correspond to only one pixel area, but may correspond to several pixel areas in a direction perpendicular to the scanning direction of the recording head 10. A multi-pixel configuration is possible. In addition, one small aperture 17 facing one heat generating part 16 is provided in one pixel area.
Basically, the small apertures 17 are arranged to face each other, but as shown in FIG. 3, a plurality of small apertures 17 may be arranged to face each other in one pixel area.

The recording head 10 has a rail z disposed on a stationary member.
The housing 1 is mounted on a movable scanning table 22 that is movable along iVc.
2 is fixed, and its movement is controlled by an operating wire 23 connected to a movable scanning table 22. A shaft 26 of a transport roller 25 for transporting the recording paper 24 is disposed parallel to the rail 21, that is, parallel to the scanning direction of the recording head lo. At the end of 2G, it is rotatably supported by a support stand 27 fixed to an immovable member.

The support stand 2 supported by one end of the shaft 26 of the conveyance roller 25
7 is provided with a capping head 30 which is a device for preventing clogging of the recording head 100.

That is, a case 31 of the capping head 30 is fixed to the side of the support base 27 facing the rail 21, and inside the case 31 there is a flexible porous material having continuous air permeability, as shown in FIG. A member 32 is housed. This porous member 32 has a cutout window 31a of the case 31 formed on the side facing the recording head 10 running on the rail 21.
(See FIG. 4) A portion 32a is exposed and protrudes. As is clear from FIGS. 3 and 3, this protrusion 32a has an arcuate shape when viewed from above. The porous member 32 is
For example, it is made by mixing a foaming agent into a soft raw material such as rubber or plastic and performing a molding process, and this porous member 32 is impregnated with a low-volatile solvent. As low volatility solvents, hydrophilic solvents include
For example, polyethylene glycol MW200-600.
Glycerin, triethanolamine, etc. are used, and as an oily solvent, for example, silicone oil of various viscosities can be used. A small hole 33 is formed in the upper plate of the case 31 to communicate the pressure inside the case 31 with the outside air, and when the pressure inside the case 31 increases due to changes in temperature or atmospheric pressure, it is held by the porous member 32. This prevents low-volatile solvents from flowing away.

Next, the operation of the inkjet recording head and the effect of the clogging prevention device will be explained.

When the recording head 10 performs the recording operation, the recording head 10 moves the recording paper 24 supported by the conveying roller 25.
It exists on the rail 21 at a position facing the. In the recording head 10, the heating element 16 generates heat when a recording signal is applied to the heating element head 13, whereby the liquid ink 11 evaporates and expands to generate bubbles, and the pressure of the bubble causes the ink to decrease. The droplet flies toward the recording paper 24 through the small opening 17. At this time, if the small opening 17 is filled with ink, the ink in the small opening 17 will fly, but if the small opening 17 is not filled with ink, the ink in the gap 18 will fly. It will fly through the small opening 17. In either case, since the gap 18 is minute, the pressure of the bubble formed by the heat generation effect of the heat generating part 16 diffuses and becomes weaker, and before it diffuses to the adjacent pixel area, the pressure of the bubble becomes strong enough to cause the ink to fly. It will be converted.

The recording head 1O records one line on the recording paper 24 by reciprocating the movable scanning table 22 on the slider 21, and when the recording for one line is finished, the conveying roller 25 rotates. The recording paper 24 is fed by one line in a direction perpendicular to the scanning of the recording head 10.

During the recording operation, the recording head 10 moves along the recording width corresponding to the recording width, does not stop at the same position, but moves over the recording width that has been reciprocated above on the conveyor roller 25. When it reaches a position facing the capping head 3o present at one end of the shaft 26, it comes to a stopped state. That is, when the recording head 10 is not in use, the ink filling the small opening 17 or the gap 18 gradually evaporates through the small opening 17, and as a result, solid components of the ink are deposited on the opening wall of the small opening 17. In this embodiment, when the print head 10 is in a non-printing state, the capping head 3011C is always attached to the capping head 3011C. It reaches the opposite position and stops. The recording width by the recording head 1° does not necessarily cover the entire width of the recording paper 24 to which it is applied. Preferably, the capping heads are opposed by 3°.

When the recording head 10 stops facing the capping head 3CHC, the plate-like member 14 at the tip of the recording head 1o
The small opening 17 formed in the capping head 3
Projection 3 of porous member 32 exposed from case 31 of o
2a and is sealed by the porous member 32 and the low-volatile solvent impregnated into the porous member 2a. That is, the small opening 17 is tightly closed by the porous member 32 impregnated with a low-volatile solvent, thereby preventing the liquid ink 11 of the recording head 10 from being vaporized through the small opening 17. Since the small opening 17 is formed in the thin plate-like member 14 with a planar spread, the porous member 32 is in close contact with the plate-like member 14 over a wide area, and the porous member 32 has high flexibility. In addition, since the sealing is performed using a low-volatility solvent, its sealing action is extremely effective. In addition, porous member 3
For No. 2, it is only necessary to emphasize the function of holding a low-volatile solvent, so a material with sufficiently increased flexibility can be applied.

The plate-like member 14Ili is made of a thin metal such as stainless steel or nickel with a thickness of about 10 to 100 microns by etching or electroforming.
7 is preferably formed, and in order to maintain the flatness of such a thin plate-like member 14 and to form a minute gap 18, the plate-like member 14 has a curved shape. Although it cannot be said that the porous member 32 has sufficient strength against external forces, the porous member 32 has high flexibility, so even if the porous member 32 is closely attached to the plate member 14, the plate member 14
The force exerted on the plate member 14 is extremely weak, and there is no possibility that the plate member 14 will be extremely deformed.

Note that the porous member 32 needs to have continuous air permeability and have a structure with communicating voids, but it does not necessarily have to be a foam, and it can be made of a felt-like material or other material with entangled fibers. It may be a structure. In addition, the porous member 32
The low-volatile solvent impregnated with the
The solvents described in No. 7 can also be applied.

Since the small opening 17 has a small diameter, even if the porous member 32 impregnated with the low-volatility solvent of 17-karat gold is tightly sealed and sealed, the liquid ink 11 and the low-volatility solvent for this sealing It almost never mixes with solvents.

Therefore, it does not matter whether the low-volatility solvent is soluble or insoluble in the liquid ink 11. Furthermore, even if the low-volatile solvent is mixed into the small opening 17, it will not cause any problem during recording because it will be easily removed during the printing process of the recording head.

A low-volatile solvent is a solvent with low volatility, as the word suggests, but it is not completely non-volatile, and
Repeated contact and separation from the plate-like member 14 may cause it to adhere to the plate-like member 14 and decrease. Therefore, if the low-volatile solvent held in the porous member 32 decreases to an amount that is unfavorable to the sealing effect, the capping head 30 must be replaced with each case 31, or
By replenishing the case 31 with a low-volatile solvent to restore its function, the case 31 can be used again, and maintenance is simple.

In the above embodiment, the recording head 10 is moved to the position of the fixedly installed capping head 30 to seal the small opening 17, but the present invention has such a configuration. However, the capping head 30 may be moved to the stop position of the recording head 10 to seal the small opening 17.

Further, the inkjet recording head to which the clogging prevention device of the present invention is applied is not limited to the recording head 1O as in the embodiment described above in which the small opening 17 is formed in the plate-like member 14, but also the inkjet recording head to which the clogging prevention device of the present invention is applied. It has a small opening such as an orifice or nozzle in the shape of a It can be applied to any type of inkjet recording head to prevent the small openings from being clogged with ink.

(Effects of the Invention) As described above, according to the present invention, the small openings are sealed to prevent ink from vaporizing when the inkjet recording head is not recording, thereby preventing clogging of the small openings with ink. In addition, since the effect of sealing small openings such as orifices and nozzles of the recording head is mainly performed by a low-volatile solvent, the sealing effect is reliable. Since a sufficiently flexible material can be used to hold the small opening forming member, there is no risk of deforming the small opening forming member by sufficiently reducing the pressure applied to the small opening forming member, and furthermore, the above solvent can be used. Since the held porous member is brought into close contact with the recording head from the outside, it does not affect the recording head by complicating its structure in any way, and has excellent effects such as easy maintenance. demonstrate.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an inkjet printer to which a clogging prevention device according to an embodiment of the present invention is applied. FIG. 2 is a partially cutaway front view of the inkjet printer shown in FIG. 1 above. 3 is an enlarged sectional view of the main part in FIG. 1, and FIG. 4 is a sectional view of the clogging prevention device in FIG. 2. FIG. 5 is a sectional view showing an example of a conventional clogging prevention device. 10-#-・Inkjet recording head 11・・・Liquid ink 14・・・Plate member (small opening forming member) 17・・■ Small opening 18・・Gap part 21III 111・Rail 22・・・・24 movable scanning tables --- Recording paper 30 --- Capping head (clogging prevention device) 3
1...Case 32...Flexible porous member with continuous air permeability impregnated with a low-volatility solvent Figure 3 Case 47

Claims (1)

[Scope of Claims] One of small openings such as orifices and nozzles formed in the small opening forming member is made to face the recording medium, and the other is communicated with the ink chamber, and ink droplets are directed onto the recording medium through the small opening. In an inkjet printer having an inkjet recording head that performs recording by moving the small opening forming member and the recording medium relative to each other, when the inkjet recording head is in a non-recording position, the same position The recording head is characterized in that a flexible porous member impregnated with a low-volatile solvent and having continuous air permeability is brought into close contact with one surface of the small opening of the recording head to seal the small opening. A clogging prevention device for inkjet recording heads.