JPH1128813A - On-demand type multi-nozzle ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the influence of crosstalk even in the case multiplicity division driving is not conducted by forming a part of the wall of an ink passage into a sheet plate having the same spring strength as a diaphragm and disposing an elastic material on the surface of the sheet plate opposite to the surface to be immersed in ink. SOLUTION: A diaphragm 3, restrictor plate 11, chamber plate 12, and ink passage cover 14 are made of, e.g. a stainless material, and the orifice plate 13 is made of electrocast nickel. Also, the stationary plate 6 consists of an insulation material such as ceramics and polyimide. An elastic material 16 coated on the sheet plate passage cover 14 of ink serves to absorb the oscillation energy of ink. As such, the variation of ink pressure created at the compression chamber 2 of any nozzles is avoided from being transmitted to the contiguous nozzle by the way of the ink passage via ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type ink jet head using a piezoelectric element, and more particularly to a structure effective for reducing crosstalk of a multi-nozzle ink jet head having a large number of nozzles integrated at a high density. .

[0002]

2. Description of the Related Art A conventional ink jet head has a configuration shown in FIG.

An orifice plate 13 in which a plurality of orifices 1 are formed, a chamber plate 12 provided on the orifice plate 13 to form a pressurizing chamber 2, and a list for controlling the amount of ink supplied to the pressurizing chamber 2 A restrictor plate 11 constituting the restrictor 8, a vibrating plate 11 forming at least a part of a wall surface of the pressurizing chamber 2 and connected to the piezoelectric element 4, and an ink flow path communicating with a plurality of restrictors 8 At 7 a nozzle is configured.

The piezoelectric element 4 has one end fixed to a fixed substrate 6 and the other end fixed to the diaphragm 6 via an elastic material 10 (silicon rubber in this example). It expands and contracts according to the input signal to 5b.

In the above configuration, the diaphragm 6 is elastically deformed by the expansion and contraction of the piezoelectric element 4 to suck the ink into the pressurizing chamber 2 and then pressurize, whereby the ink droplet is ejected from the orifice 1.

In an on-demand type ink jet head having a plurality of nozzles as described above, for example, when printing a solid pattern, all the nozzles are driven at a high frequency. At this time, the speed of the ink droplets ejected from the nozzles is often reduced due to mutual interference between the nozzles as compared with the case where one nozzle is driven alone (this is usually referred to as “speed reduction due to crosstalk”). Is called). For this reason, the landing position of the ink droplet shifts due to the decrease in speed, and the dot size varies due to the decrease in the amount of ink, so that good print quality cannot be obtained.

Conventionally, in order to reduce crosstalk, a method of reducing the number of nozzles for simultaneous injection has been adopted. For example, 1, 2, 3,...
.. Are divided into two groups, odd-numbered nozzles and even-numbered nozzles, and are driven with a time difference. In such a division drive, the nozzles may be divided into three or more groups in order to further reduce the number of simultaneous injection nozzles.

[0008]

When ink is ejected by multiple division driving as described above, the driving circuit becomes complicated. In addition, there is a problem that the injection timing for each group becomes short, and the width of the drive pulse cannot be made large.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a head structure in an on-demand type multi-nozzle ink jet head having a plurality of nozzles, in which the influence of crosstalk is reduced without performing multiple division driving.

[0010]

According to the present invention, there is provided a pressure chamber for increasing the pressure of ink, a piezoelectric element for causing a pressure change in the ink in the pressure chamber by applying an electric signal, A vibrating plate that forms at least a part of the wall surface of the pressurized chamber, the vibrating plate to which the piezoelectric element is connected, and a restrictor that forms a flow path that controls the amount of ink supplied to the pressurized chamber;
An on-demand type multi-nozzle inkjet head having a plurality of nozzles each comprising an orifice for ejecting ink droplets from a pressurized chamber and having an ink flow path upstream of a restrictor and supplying ink to the plurality of nozzles ,
A part of the wall of the ink flow path is a thin plate having the same spring strength as the diaphragm, and an elastic material is provided on a surface of the thin plate opposite to a surface immersed in ink.

With the above arrangement, the pressure fluctuation transmitted from the pressurizing chamber to the ink flow path by the ink ejection is attenuated by the thin plate of the ink flow path, and the propagation of the pressure fluctuation generated through the ink to the adjacent nozzle is performed. Can be prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a nozzle portion of a multi-nozzle ink jet head used in the present invention. This head can perform recording by ejecting ink according to an input signal.

1 is an orifice, 2 is a pressurizing chamber, 3 is a vibration plate, 4 is a piezoelectric element, 5a and 5b are signal input terminals, 6 is a head substrate, 7 is an ink flow path, and 8 is an ink flow path 7. A restrictor that connects the pressure chamber 2 and controls the flow of ink into the pressure chamber 2, a filter 9 that traps dust in the ink that causes nozzle clogging, and a filter 10 that connects the diaphragm 3 and the piezoelectric element 4. Elastic material (here, silicone rubber of a polymer material) to be connected, 11 is a restrictor plate forming the restrictor 7, 12 is a chamber plate forming the pressurizing chamber 2, 13 is an orifice plate forming the orifice 1, 14 Denotes a plate thickness required to form the ink flow path 8.
A 015 mm ink flow path cover, 15 is an ink flow path cover support for supporting the ink flow path cover 14, and 16 is a heater for heating the ink, which is in close contact with the elastic member 16.

The diaphragm 3, the restrictor plate 11, the chamber plate 12, and the ink passage cover 14 are made of, for example, stainless steel, and the orifice plate 13 is made of electroformed nickel. The fixed substrate 6 is made of an insulating material such as ceramics and polyimide.

The piezoelectric element 4 is mounted such that it expands or contracts when a voltage is applied between the signal input terminals 5a and 5b, and does not deform if there is no potential difference between the signal input terminals 5a and 5b.

The ink is sucked up in the order of the ink channel 7, the restrictor 8, the pressurizing chamber 2, and the orifice 1 by the expansion and contraction of the piezoelectric element 4. At the time of ejection, a part of the ink flows backward in the order of the pressurizing chamber 2, the restrictor 8, and the ink flow path 7.

In the head of the present invention, 32
They are formed from nozzles and are arranged in 12 rows.

In such a structure, in printing a solid pattern, all or most of the nozzles formed in the head are simultaneously driven at a high frequency, and the pressure fluctuation generated in the pressure chamber 2 of a certain nozzle is caused by ink fluctuation. Through the restrictor 8, the ink flow path 7, and the restrictor 8 of the adjacent nozzle, the light is transmitted to the pressurizing chamber of the adjacent nozzle.
Therefore, the speed of the ink droplet and the amount of ink at the time of ejection change in the adjacent nozzles due to the influence of the pressure fluctuation received from the adjacent nozzle. In such a case, conventionally, the ink droplet speed and the ink amount often decrease, and it is desired to prevent these and enable high-speed printing.

In this embodiment, since a part of the wall of the ink flow path, here, the ink flow path cover 14 is thinned and silicon rubber of the elastic material 16 is applied, the pressure chamber 2 of the nozzle is used. The generated pressure fluctuation is attenuated even if it is propagated from the restrictor 8 to the ink flow path 7 using ink as a medium.
Specifically, the elastic material 16 applied to the thin ink passage cover 14 absorbs the vibration energy of the ink. In this way, the fluctuation of the ink pressure generated in the pressure chamber 2 of a certain nozzle is not transmitted to the adjacent nozzle via the ink flow path via the ink.

FIG. 3 shows a conventional ink jet head provided with 32 nozzles forming one row of an ink jet head according to the present invention and an ink flow path cover having a plate thickness of 0.4 mm to which no elastic material 16 is applied. 7 is a graph comparing speed ratios showing the effect of crosstalk for 32 lines constituting one row of the inkjet head of FIG. Here, the speed ratio is
This is a value obtained by dividing the ink droplet speed ejected from each nozzle when 32 nozzles are evenly and oddly divided into two and jetting 16 nozzles simultaneously by the ink speed when each nozzle is jetted independently.

FIG. 3 shows that in the nozzle of the ink jet head of the present invention, the speed ratio is close to 1 and the speed in the case of two divisions is almost equal to the speed in the case of the single unit, and the crosstalk is small.

[0023]

According to the present invention, it is possible to greatly reduce crosstalk caused when a large number of nozzles are driven simultaneously, and to provide a nozzle capable of high-speed, high-quality printing. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a nozzle of an inkjet head according to the present invention.

FIG. 2 is a sectional view of a nozzle of a conventional inkjet head.

FIG. 1 is a graph comparing the effects of crosstalk.

[Explanation of symbols]

1 is an orifice, 2 is a pressure chamber, 3 is a vibration plate, 4 is a piezoelectric element, 5a and 5b are signal input terminals, 6 is a head substrate, 7 is an ink flow path, 8 is a restrictor, 9 is a filter, and 10 is a filter. Silicon rubber, 11 is a restrictor plate, 12 is a chamber plate, 13 is an orifice plate, 14 is an ink flow path cover, 15 is an ink flow path cover support,
16 is a heater.

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[Procedure amendment]

[Submission date] September 5, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a nozzle of an inkjet head according to the present invention.

FIG. 2 is a sectional view of a nozzle of a conventional inkjet head.

FIG. 3 is a graph comparing the effects of crosstalk.

[Description of Signs] 1 is an orifice, 2 is a pressure chamber, 3 is a vibration plate, 4 is a piezoelectric element, 5a and 5b are signal input terminals, 6 is a head substrate, 7 is an ink flow path, 8 is a restrictor, 9 Is a filter, 10 is a silicone rubber, 11 is a restrictor plate, 12 is a chamber plate, 13 is an orifice plate, 14 is an ink flow path cover, 15 is an ink flow path cover support,
16 is a heater.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuaki Akimoto 1060 Takeda, Hitachinaka-city, Ibaraki Pref., Hitachi Koki Co., Ltd. (72) Inventor Nobuhiro Kurosawa 1060 Takeda, Hitachinaka-shi, Ibaraki Pref. Inventor Takao Matsuoka 1060 Takeda, Hitachinaka City, Ibaraki Pref.Hitachi Koki Co., Ltd.

Claims (1)

[Claims] A pressure chamber for increasing the pressure of the ink, a piezoelectric element for causing pressure fluctuation in the ink in the pressure chamber by application of an electric signal, and at least a part of a wall surface of the pressure chamber, the piezoelectric element comprising: A diaphragm to which elements are connected, and a restrictor that forms a flow path that controls the amount of ink supplied to the pressurized chamber,
An on-demand type multi-nozzle inkjet head having a plurality of nozzles each comprising an orifice for ejecting ink droplets from a pressurized chamber and having an ink flow path upstream of a restrictor and supplying ink to the plurality of nozzles A part of the wall of the ink flow path is a thin plate having the same spring strength as the diaphragm, and an elastic material is provided on a surface of the thin plate opposite to a surface immersed in ink. On-demand type multi-nozzle inkjet head.