JPH01306257A - Ink jet head - Google Patents

Abstract

PURPOSE:To smoothly supply ink by discharging bubbles of the side of an ink cassette disturbed by an ink filtering filter extended to an ink supply port, stored in an upper part by rising in a second ink chamber through the passage of a bubble discharging nozzle. CONSTITUTION:Bubbles 23 from the side of an ink cassette 13 is kept from invasion into a common ink chamber 24 by a filter 28 extended to an ink supply port 25, and rises in a second ink chamber 26 to be stored in an upper part. Thus, the bubbles are stored in the front face of the filter 28 extended to the inlet of the ink to the chamber 24, do not block it, and do not disturb the flow of the ink supplied to the chamber 24. The bubbles 23 stored in the upper part of the chamber 26 are discharged by discharging means such as pressurization, suction, etc. through the filter 28 and a passage 29 to a bubble discharging nozzle 27. Accordingly, the bubbles mixed at the time of connecting the cassette do not stop supplying the ink and the ink can be smoothly supplied.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of drop, on-demand, and demand type inkjet heads, the purpose is to prevent air bubbles in the supplied ink from being trapped in the ink filtration filter section and blocking the ink flow. A nozzle array with a plurality of nozzles arranged in a row, a common ink chamber that supplies ink to each nozzle, an ink supply port that supplies ink to the common ink chamber, and an ink supply port that is separated from the common ink chamber by the ink supply port. bubble discharge nozzles arranged in parallel at the upper part of the nozzle row for discharging bubbles in the supplied ink through the second ink chamber, the ink supply port and the common ink chamber, and the ink supply port and the second ink chamber. It consists of an ink filtration filter that covers the boundary surface.

[Industrial application field]

The present invention relates to the structure of a drop, on-demand, inkjet head.

Recently, various serial printers have been used as input/output terminals of data processing devices, word processors, and the like.

Among them, serial dot printers print characters etc. composed of dots, so there is an extremely wide variety of characters etc. (Office Automation (OA)
It is increasingly being used as a terminal device in mobile applications.

In particular, inkjet printers eject ink droplets from nozzles to record, so they do not generate noise, can record at high speed and with high image quality, are easy to print in color, and can use inexpensive plain paper. It is attracting attention due to its many advantages such as low running cost (no need for development and fixing).

[Conventional technology]

As shown in the plan view of FIG. 2, the drop-on-demand printer to which the present invention is applied reciprocates an inkjet head 1 equipped with a plurality of nozzles, and pressurizes predetermined nozzles to emit ink droplets. It is configured so that the paper is ejected and recorded on opposing paper, and the side frames 2 on both sides
A platen 3 is rotatably held by a and 2b, and a sheet of paper 4 is wound around the platen 3 so that a line feed is carried out in the direction of arrow A and the paper is discharged.

On the other hand, a carrier 5 is movably engaged with guide shafts 6 and 7 provided parallel to the platen 3 on the front surface (lower side in the figure) of the platen 3.
An endless belt-shaped timing belt 8 is provided in parallel with the pulleys 9 and 10, and one side 8a of the timing belt 8 is stretched by the forward and reverse rotation of the pulley 9 connected to the motor 11.
The carrier 5 fixed thereto moves back and forth as shown by arrow B-C.

An inkjet head 1 is mounted on the carrier 5, and ink is supplied to the inkjet head 1 from an ink cassette 13 via a bendable tube 12.

Therefore, recording on the paper 4 is performed by reciprocating the inkjet head 1 together with the carrier 5, selecting a plurality of nozzles of the inkjet head 1, pressurizing them with a pressurizing means, and ejecting the ink in the nozzles in droplets.

As shown in the side view of FIG. 3, the inkjet head 1 has a nozzle row 15 composed of a predetermined number of nozzles 14 arranged in the direction of gravity, and a pressurizing means such as a piezoelectric element, which communicates with each nozzle 14. A pressure chamber 17 (hereinafter referred to as a piezoelectric element) that applies pressure to the ink and ejects ink droplets from the nozzle 14, a common ink chamber 18 that supplies ink to the pressure chamber 17, and an ink cassette in the common ink chamber 18. An ink supply port 21 that supplies ink from 13 through the tube 12, and a filter provided at the interface between the ink supply port 21 and the common ink chamber 18 to filter the ink and remove dust from the ink. It is composed of 22.

Therefore, the ink from the ink cassette 13 is divided into each nozzle 14 via the common ink chamber 18 and the pressure chamber 17, and is dripped from the nozzle 14 by driving the piezoelectric element 16 provided integrally with the pressure chamber 17. Then it sprays.

On the other hand, ink pools occur between the nozzles 14 on the nozzle surface 19 due to the ejection of ink droplets from the nozzles 14; Since the nozzle 14 is under negative pressure, no large pool is formed.

However, the ink flows out to the upper and lower ends of the nozzle row 15 to the edge portions 19a and 19b of the nozzle surface 19, forming a large ink pool toward the outside.

Among these ink puddles, small ink puddles between the nozzles do not cause any problems in the operation of the nozzle 14, but large ink puddles formed above and below may bend the ejecting direction of ink droplets, or in extreme cases may cause ink droplets to be ejected. The problem arises if you don't.

For this purpose, dummy nozzles 20a and 20b (
This is handled by establishing a policy that does not involve record-keeping.

By providing such dummy nozzles 20a and 20b, large ink pools can be removed from the dummy nozzles 20a and 20b.
30a and 30b are formed between the edge portions 19a and 19b, and the wetting of the nozzle portion 14 is made uniform, thereby preventing an adverse effect on the ejection of ink droplets.

The upper dummy nozzle 20a among these dummy nozzles is
It also serves as a discharge hole for air bubbles in the ink.

For example, when the ink cassette 13 is connected, air bubbles mixed into the ink and passed through the filter 22 rise in the common ink chamber 18 and are removed by means such as pressurizing the ink from the ink cassette or suctioning the nozzle. It is discharged to the outside through the dummy nozzle 20a.

[Problem to be solved by the invention]

Although air bubbles in the ink are discharged as described above, in reality, the mesh diameter of the filter 22 is 20 to 30 μm.
mφ and the nozzle diameter of about 50 μmφ, and the air bubbles 2
3 is trapped by the filter 22 due to the surface tension of the ink, and gradually accumulates as shown in the enlarged side view of the ink supply port 21 in FIG.
), the entire front surface of the filter becomes a large bubble 23, stopping the supply of ink to the nozzle.

Even if the air bubbles accumulated on the front surface of the filter overcome the surface tension by means of pressurization or suction and flow into the flow path, the long flow path through the common ink chamber 18 becomes an obstruction and they adhere to the flow path. There was a problem that it was difficult to overcome.

An object of the present invention is to prevent air bubbles in supplied ink from being trapped in an ink filtration filter section, thereby preventing the flow of ink from being blocked.

[Means to solve the problem]

In order to achieve the above object, in the present invention, FIG.
As shown in the side view of al, there is a nozzle row 15 in which a plurality of nozzles 14 are arranged in the direction of gravity, a common ink chamber 24 that supplies ink to each nozzle 14, and an ink supply port that supplies ink to the common ink chamber 24. 25, and a second ink chamber 2 separated from the common ink chamber 24 by the ink supply port 25.
nozzle array 15 for discharging air bubbles in the supplied ink via 6;
, an ink filtration filter 28 that covers the interface between the ink supply port 25 and the common ink chamber 24, and the ink supply port 25 and the second ink chamber 26. It is something.

[Effect]

Air bubbles on the ink cassette side that are blocked by the ink filtration filter stretched over the ink supply port rise within the second ink chamber and accumulate in the upper part.

Therefore, air bubbles do not block the ink inlet to the common ink chamber, and ink inflow to the common ink chamber is not hindered.

The air bubbles accumulated in the upper part of the second ink chamber are passed through the flow path of the air bubble discharge nozzle that is in direct contact with the filter.
It can be discharged by means of pressurization, suction, etc.

〔Example〕 FIG. 1 shows one embodiment of the present invention.

Identical parts are designated by the same reference numerals throughout the design.

In the present invention, as shown in the side view of FIG.
As in the prior art, a nozzle row 15 in which a predetermined number of nozzles 14 are arranged in the direction of gravity, and a pressure chamber 17 that communicates with each nozzle 14 and applies pressure to the ink with a piezoelectric element 16 to eject ink droplets from the nozzles 14. , a common ink chamber 24 that supplies ink to the pressure chamber 17, and an ink supply port 25 that supplies ink to the common ink chamber 24. ), the ink supply port 25 separates the ink from the common ink chamber 24, and the ink cassette flows through the second ink chamber 26 arranged parallel to the common ink chamber 24, and the ink cassette via the second ink chamber 26. In order to discharge air bubbles in the ink supplied from the ink supply port 13, there are provided air bubble discharge nozzles 27 arranged in parallel at the upper part of the nozzle row 15, an ink supply port 25 and a common ink chamber 24, and an ink supply port 25 and a common ink chamber 24. 2
An ink filtration filter (hereinafter referred to as a filter) 28 that covers the interface with the ink chamber 26 is provided.

Therefore, the air bubbles 23 from the ink cassette 13 side are prevented from entering the common ink chamber 24 by the filter 28 stretched over the ink supply port 25, and the air bubbles 23 are prevented from entering the common ink chamber 24.
It rises inside and accumulates at the top.

Therefore, air bubbles do not accumulate on the front surface of the filter 28 provided over the ink inlet to the common ink chamber 24 and block it, and the inflow of supplied ink into the common ink chamber 24 is not hindered.

In addition, the capacity of the second ink chamber 26 is larger than that of the ink supply port, and the air bubbles 23 that have accumulated in the second ink chamber 26 for a considerable period of time hardly pose a problem in use.

The bubbles 23 accumulated in the upper part of the second ink chamber 26 are discharged through the bubble discharge nozzle 27 by a discharge means such as pressurization or suction.

The end (inflow port) of the flow path 29 of this bubble discharge nozzle 27
is in direct contact with the bubbles 23 via the filter 28, and the discharge means directly acts on the bubbles 23, so that at least the lower part of the inlet to the bubble discharge nozzle 27 is easily discharged.

〔Effect of the invention〕

As explained above, by using the inkjet head of the present invention, air bubbles that get mixed in when connecting an ink cassette, etc., are not trapped by the ink filtration filter and stop the ink supply, and smooth ink supply is achieved. It has great economic and industrial effects, such as being able to supply ink and improving the reliability of inkjet printers.

[Brief explanation of the drawing]

FIG. 1(a) is a side view of the inkjet head of the present invention, FIG. 1(b) is an enlarged cross-sectional view taken along the line D-E in FIG. 1(a), and FIG. . FIG. 3 is a side view showing a conventional inkjet head, and FIGS. 4(a) and 4(b) are enlarged side views of a conventional ink supply port. In the figure, 12 is a tube, 13 is an ink cassette, 1
4 is a nozzle, 15 is a nozzle row, 16 is a pressurizing means (piezoelectric element), 17 is a pressure chamber, 18.24 is a common ink chamber, 19 is a nozzle surface, 20a, 20b are dummy nozzles, 21.25 is an ink supply 22, 28 is an ink filtration filter, 23 is a bubble, 26 is a second ink chamber, 2
7 is a bubble discharge nozzle, and 29 is a flow path. 1st edition (α) of the ink of the present invention S'L-z
) (α) (b) A through K, G I〉Fi 戎斎口゛size A6mm page 1 shi is GJ 4 distance

Claims (1)

[Claims] A nozzle row (15) in which a plurality of nozzles (14) are arranged in a row;
a common ink chamber (24) that supplies ink to each of the nozzles (14); an ink supply port (25) that supplies ink to the common ink chamber (24); and a common ink supply port (25) that supplies ink to the common ink chamber (24). Room (24)
a bubble discharge nozzle (27) arranged in parallel at the upper part of the nozzle row (15) for discharging bubbles in the supplied ink via a second ink chamber (26) provided separately from the ink; The supply port (25) and the common ink chamber (24), and the ink supply port (25) and the second ink chamber (26).
) and an ink filtration filter (28) that covers the interface with the inkjet head.