JPH02143862A - Ink-jet head - Google Patents

Abstract

PURPOSE:To easily remove air bubbles from a head arranged at any position without detaching said head from a unit, by providing two ports in a nozzle forming face of said head at the top and bottom of an inner chamber to remove the air bubbles. CONSTITUTION:Outlets 312, 312' of passages 311, 311' communicating with the outside of an inner chamber 3 are formed on a surface where an air discharge nozzle 7 is formed. The outlets 312, 312' are freely opened and closed by respective cocks 7-221, 1'-221'. Inlets 1-310, 1'-310' are provided at the top and the bottom of the inner chamber 3 to remove the air bubbles in the chamber 3, which are connected by passages 1-311, 1-311'. For removing the air of the chamber 3, two outlets are provided, one being connected to a pipe to supply a filling liquid such as ink, ink solvent or water. The filling liquid is injected with pressure from the one outlet and discharged out from the other outlet. Accordingly, a strong flow is generated in the upper part of the inner chamber 3, whereby the air bubbles adhered to the top or the other wall surfaces of the chamber 3 are scraped and quickly removed. Thus, even when the head is inclined, maintenance work can be done easily from the front face of the unit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an inkjet head that performs drop-on-demand bubble removal having a two-chamber structure in an inkjet recording device used in color printers, copying machines, etc. It is related to.

2. Description of the Related Art Conventionally, in a drop-on-demand head having a two-chamber structure, air bubbles existing inside the ink chambers are vented by providing a passage leading to the outside at the top of each ink chamber. For example, a configuration described in Japanese Patent Application Laid-Open No. 51-21439 is known.

A brief explanation will be given below with reference to the drawings.

As shown in FIG. 7, in the inkjet head 1, passages 21 and 31 that communicate with the outside of the head 1 are formed in the outer chamber 2 and the inner chamber 3, respectively, and the respective passages are connected by plugs 22 and 32. It can be closed.

And whatever the cause, outer chamber 2 and inner chamber 3
If air bubbles are present in the head, the performance of the head will be significantly reduced. For this reason, air bubbles in the ink chamber must be removed. In this case, air bubbles tend to rise due to buoyancy and move to the top of each chamber, so when pressure is applied to the ink in the ink reservoir (not shown) and the plug 22 or 32 is removed or loosened, the pressure is increased. Ink flows in from the ink supply pipe 6, and some ink flows out from the ink discharge nozzle 4, but most of the ink passes through the outer chamber 2 and enters the passage 21.
It overflows to the outside with more air bubbles. Then, when the passage 21 is closed, the ink flows into the inner chamber ≠ of the coupling passage 5, and the air bubbles existing at the top of the inner chamber 3 overflow from the passage 31 together with the ink, so that the plug 32 is returned to its original state. The function of the head is restored by returning the head to normal.

Next, FIG. 8 shows a device in which an air nozzle 7 having an opening is provided opposite to the ink discharge port 4, so that ink droplets are accelerated by an air flow. A passage 81 leading to the outside is formed in the air chamber 8, and the passage 81 is closed by a stopper 82. This passage 81 is for cleaning the inside of the air chamber 8.

Problems to be Solved by the Invention However, in conventional inkjet heads, it is necessary to dispose of overflowing ink, and for color printing, an inkjet unit in which heads 1011 to 1034 are arranged in a matrix as shown in FIG. With the 100, the spacing between the heads is small, so if you need to remove air bubbles or clean the air chamber, each stopper cannot be removed as it is, so you have to remove the relevant head, and the installation requires readjusting the nozzle position later. maintenance work is extremely difficult. On the other hand, the uppermost head 1031-1 allows air bubbles to be removed without removing the head from the unit.
034 as well, the nozzle surface faces diagonally downward due to its positional relationship with the recording drum, and naturally, as shown in Figure io, the air bubbles 1
2 moves to a blind spot of ink flow. In this state, since the amount of ink flowing in from the minute coupling passage 4 is small, it is not possible to obtain enough ink flow to move the air bubbles accumulated in the dead area, and it is difficult to remove the air bubbles. There was a problem.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to make it possible to easily remove air bubbles from any position of the head without removing the head from the unit.

Means for Solving the Problems To achieve the above object, the technical means of the present invention is to provide passages at the top and bottom of the inner chamber, and at the same time provide the passage outlet on the nozzle forming surface. .

Function The present invention provides two outlets for the air vent passage of the inner chamber on the nozzle surface side of the head which is always exposed in an inkjet unit, and a reservoir for injecting ink, ink solvent, or filling liquid such as water into one outlet. By connecting the above pipe and injecting the filling liquid under pressure and flowing out from the other outlet, a strong flow is generated in the upper part of the inner chamber, and air bubbles attached to the top of the inner chamber or other wall surfaces are generated. can be removed and quickly removed. This allows maintenance work to be easily performed from the front of the unit even if the head is tilted.

EXAMPLES The present invention will be described below with reference to the drawings. 1 is a front view of an inkjet head according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing a cross section taken along line AB in FIG. 1, FIG. 3 is a partial perspective view of the chamber inside the head, and FIG. 5 is a front view of an inkjet unit using the same head, and FIG. 6 is a side view of the same.

In FIGS. 1 and 2, if air bubbles exist in the outer chamber 2, air pressure is applied only to the ink reservoir (not shown).
Pressurized ink is supplied from the ink supply pipe 6. Further, a passage 200 leading to the upper part of the outer chamber 2 is connected to a flexible tube via a bubble removal pipe 201. This flexible tube is provided with an opening/closing cock (not shown), the tip of which is led to the outside of the head unit. Then, by opening the cock, the air bubbles in the outer chamber 2 are suppressed by the ink because the pressurized ink flows into the outer chamber 2, and the air bubbles are suppressed by the ink, and the air bubbles are suppressed by the ink. be excluded from the outside.

Next, bubble removal when bubbles are present in the inner chamber 3 will be explained.

The passage outlets 312, 312 of the two passages 311, 311 communicating with the outside of the inner chamber 3 are provided on the surface where the air discharge nozzle 7 is formed, and the passage outlets 312, 312 are each connected to the plug-12.
21, it can be opened and closed with the stopper 1221.

Next, as shown in FIGS. 2 and 3, a passage inlet 1310 and a passage inlet 13 for removing air bubbles from the inner chamber 3.
10 are provided at the top and bottom of the inner chamber 3, respectively, with passages -
1311 and passage -1311.

Therefore, if air bubbles are present in the inner chamber 3, first apply air pressure only to the ink reservoir (not shown), as in the case of removing air bubbles from the outer chamber 2, and from the ink discharge nozzle 4. Let the ink flow out. Then, while maintaining this state, as shown in FIG.
is removed, and with the ink overflowing from the passage outlet 312, the tube end of the filling liquid container (bag) 50 is connected to the passage outlet 312 via the connecting tube 60. Next, the plug 221 of the passage outlet 312 is removed, the cock 70 of the filling liquid container 50 is opened, and the ink in the filling liquid container is pressurized (for example, by grasping it by hand) to fill the inner chamber 3. Inject the liquid vigorously. As a result, the air bubbles accumulated at the top of the inner chamber 3 are pulled off from the wall surface by the strong flow of the filling liquid and are expelled to the outside from the passage outlet 312 together with the filling liquid. Then, by returning the plugs 221 and 221 to their original positions in this order, air bubbles can be completely removed.

After this work is completed, supply of pressurized air to the air chamber 8 of the head 1 is started, thereby returning the head to a recordable state.

Note that FIG. 5 shows heads 1011 to 1034 according to the present invention.
are arranged in a 3×4 matrix, and the head 1011
The head 1011-10 is covered with a rad guide plate 9 to the extent that the nozzle surface protrudes by 1 to 2 mm other than ~1034, and a cleaning liquid for washing away mist ink generated during recording and mist ink that adheres after recording (not shown) is applied to the head 1011-10.
FIG. 6 is a front view of the inkjet UNISO 100 which is designed to prevent ink from adhering to locations other than 34, and FIG. 6 is a side view thereof. In this inkjet unit 100, instead of the difficult maintenance work (head attachment/detachment, nozzle position adjustment, etc.) that was performed with conventional types of inkjet heads, maintenance is performed from the front of the unit 100 through the dull surface and head guide plate 9. A gutter 1 is provided along the entire path along which the head unit 100 moves.
0 and collected in a waste liquid tank (not shown) together with cleaning waste liquid from a head cleaning device (not shown).

Effects of the Invention As described above, the present invention provides two air bubble vent passage openings at the top and bottom of the inner chamber on the nozzle forming surface of the head, thereby making it possible to easily perform maintenance without removing the head from the inkjet unit. In addition, there is no need to consider the treatment of unnecessary ink or filling liquid that flows out during maintenance, and the initial filling of the same head can be easily performed, which has great effects.

[Brief explanation of the drawing]

FIG. 1 is a front view of an inkjet head according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the AB cross section in FIG. 1, FIG. 3 is a partial perspective view of the chamber inside the head, and FIG. 4 5 is a front view of an inkjet unit using a plurality of the same heads, FIG. 6 is a side view of the same, FIG. 7 is a sectional view of a conventional inkjet head, and FIG. The figure is a cross-sectional view of a conventional inkjet head with an air discharge nozzle added, FIG. 9 is a front view of an inkjet unit using multiple of the same head, and FIG.
The figure is a sectional view showing the bubble positions when the head is arranged diagonally. 2 - Outer chamber, 3... Inner chamber, 4... Ink discharge nozzle, 5... Connection passage, 310, 310'...
Passage entrance, name of agent Patent attorney Shigetaka Awano and one other person Figure 10O':, 1 Figure Otsu ↑ NK No.! Figure NK

Claims (1)

[Claims] an inner chamber having a pressure increasing means, an outer chamber communicating with the inner chamber through a coupling passage provided in the inner chamber, and an ink ejection nozzle disposed in the outer chamber in line with the coupling passage; , an air nozzle having an opening facing the ink ejection nozzle, and an inlet and an outlet of a passage leading to the outside provided in the inner chamber of the inkjet head that ejects and stops minute ink droplets in response to an electric signal. an inkjet head provided with a plurality of inkjet heads, the inkjet head comprising: an inkjet head provided with a plurality of inkjet heads, wherein the passage entrances leading to the outside of the inner chamber are provided at two locations, a top and a bottom of the inner chamber.