JPS62294557A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To uniform characteristics of a plurality of nozzle heads by providing an electrode cutting section and an electrode restriction section in an electrode of a piezoelectric element to form a new electrode at the electrode cutting section, or cutting the electrode restriction section. CONSTITUTION:An effective width of a piezoelectric element 12 in a nozzle head 1 is proportional to an area of an electrode 122. When a nozzle head 1-1 having a standard characteristic L1 is used as it is, and a good characteristic L2 of a nozzle head 1-2 and a bad characteristic L3 of a nozzle head 1-3 are made to approach the standard characteristic L1 of the nozzle head 1-1, the electrode restriction sections 23 arranged at two points on the electrode 122 of the piezoelectric element 12 in the nozzle head 1-2 are cut at the two positions on a dot line 25. Consequently, the characteristic of the nozzle head 1-2 is degraded and the good characteristic L2 is brought near to the standard characteristic L1. In the nozzle head 1-3, for example a conductive material is applied onto the electrode cutting sections 24 arranged at two points on the electrode 122 thus increasing the area of the electrode 122. Consequently, the characteristic of the nozzle head 1-3 is improved and the bad characteristic L3 is brought near to the standard characteristic L1.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Application Field] The present invention relates to an inkjet recording head, and in particular, to a method for applying an information signal to a nozzle head to eject ink particles,
The present invention relates to an inkjet recording head suitable for use in a so-called on-demand type inkjet recording apparatus that records information by depositing ink particles onto a recording medium.

[Conventional technology]

An on-demand inkjet recording device generates liquid pressure in the ink by reducing the volume of the ink chamber of the nozzle head in response to an information signal, and uses this liquid pressure to eject ink particles from the nozzle hole to print information. It is recorded on a recording medium.

For this reason, a special ink pressure mechanism is not required and the structure of the printer is simple, so color printing is possible by using multiple nozzle heads. However, since the characteristics of each nozzle head are different, these It is necessary to make it uniform.

Conventionally, as described in Japanese Unexamined Patent Publication No. 51-55239, differences in the characteristics of each nozzle head have been recorded by adjusting values such as voltages applied to a plurality of nozzle heads having different characteristics. I tried not to show it.

[Problem that the invention seeks to solve]

Therefore, in such a conventional example, the adjustment circuit makes the device large and expensive, which poses a problem.

An object of the present invention is to provide an inkjet recording head that can make the characteristics of a plurality of nozzle heads uniform without providing a special GA circuit.

[Means for solving problems]

The above purpose is to
Prepare the electrode notch and electrode narrow part in advance,
The total area of the electrode can be increased by forming a new electrode in the electrode notch and connecting it to the original electrode, or by cutting the narrow part of the electrode and separating a part of the electrode from the original electrode. This is achieved by reducing the total area of the electrodes.

[Effect]

By increasing or decreasing the area of the electrodes of the piezoelectric element, the effective width of the piezoelectric element (i.e., the ejection velocity of the ink droplets ejected from the nozzle can be changed in response to changes in the value of the information signal applied to the electrodes of the piezoelectric element). Since the rate of change) can be adjusted, the different characteristics of multiple nozzle heads can be made uniform.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. Third
The figure is a schematic configuration diagram of a multi-nozzle inkjet printer.

In FIG. 3, nozzle heads lc, 1m, ly, 1. b are fixed to the carrier base 2 by fixtures 3 c + 3 m t 3 y + 3 b, respectively. The carrier base 2 is movable on rails 4 and 5 in the direction indicated by arrow A or B. And nozzle head lc, 1m, ly
, lb, ink particles 6c, 6m, 6y, respectively ejected from
6b and an image 8c on the recording body 7 that is transported in the direction shown by arrow C.

It is designed to record 8m, 8y, and 8b.

FIG. 2 is a configuration diagram of the nozzle head of the present invention, and the nozzle heads of each color in a color inkjet printer have the same configuration. In FIG. 2, the nozzle head 1 is composed of a nozzle 1o and an ink tank 20.

The nozzle 10 includes, for example, a cylindrical electromechanical transducer, that is, a piezoelectric element 12 bonded to the outer surface of a nozzle pipe 11 having a fine orifice 15 at its tip using an adhesive 16. Then, by applying the information signal 9 converted into a pulse signal of value Va to the piezoelectric element 12, hydraulic pressure is generated in the ink in the nozzle pipe 11, and this hydraulic pressure causes the ink particles 6 to be ejected from the orifice 15. It has become.

Further, the inside of the ink tank 2o is filled with ink 21, and the ink 21 is supplied to the nozzle pipe 11 via the filter 14 and the ink supply tube 13.

The relationship between the value ■d of the information signal 9 and the ejection speed V5 of the ink particles 6 is as shown in FIG.
Increasing VS increases the ejection speed VS of the ink particles 6, but the characteristics of each nozzle head in a color inkjet printer are not uniform; for example, the characteristics L+, Lx
, L8.

In this case, if the nozzle head with characteristic Ll is the standard, the nozzle head with characteristic L2 has better characteristics than the standard characteristic,
The nozzle head with characteristic L2 has worse characteristics than the standard characteristics. That is, when the ink particles 6 are ejected from the orifice 15 at the ejection speed vo, the nozzle head 1 with the characteristic L1
If the value of the information signal 9 applied to the piezoelectric element 12 of the characteristic L2 is the value ■1, the value of the information signal 9 applied to the piezoelectric element 12 of the nozzle head 1 with the characteristic L2 may be a value ■2 smaller than the value ■1. , the value of the information signal 9 applied to the piezoelectric element 12 of the nozzle head 1 having the characteristic L3 is a value v3 which is larger than the value Vl. This is due to differences in the bonding state of the piezoelectric element 12 bonded to the nozzle pipe 11 and differences in the characteristics of the piezoelectric element 12 itself.

In a color inkjet printer, it is necessary to make the characteristics of each color nozzle head the same, so in the present invention,
The shape of the electrode of the piezoelectric element 12 is as shown in FIG.

1(a) is an axial cross-sectional view of the cylindrical piezoelectric element 12 of the present invention, and FIG. 1(b) is a plane view of the electrodes on the outer surface of the cylinder of the piezoelectric element 12 shown in In the figure, side 17 is called side 17', and side 18 is called side 18',
They match each other on the cylindrical surface of the piezoelectric element 12.

In FIGS. 1(a) and (b), the cylindrical piezoelectric element 12 has an electrode 121 on the entire inner surface of the cylindrical piezoelectric material 120, and an electrode 122 on the entire outer surface of the cylindrical piezoelectric material 120. They are formed by partially plating gold or nickel with gold scraps or by applying a conductive material.

The electrode 121 is continuous from the inner surface of the cylinder of the piezoelectric body 120 to the outer surface of the cylinder of the piezoelectric body 120 via one edge 19 of the cylinder.
It has an annular gap 22 between it. Therefore 1
The piezoelectric body 120 is exposed in the annular gap 22.

On the other hand, the electrode 122 is not formed on the entire outer surface of the cylinder of the piezoelectric body 120, and as shown in FIG. 18
A rectangular electrode notch 24 is provided, which is shorter than the length D by a minute length d, and whose length in the circumferential direction of the cylinder is 0.

Therefore, the piezoelectric body 120 is exposed at the electrode notch 24. Since there are only two electrode notches 24 in the electrode 122 at an interval W8 in the circumferential direction of the cylinder, the electrode narrow part 23 of the electrode 122 whose length in the axial direction of the cylinder is a minute length d is also There are two locations.

That is, the area of the electrode 122 is the same as that of the cylindrical piezoelectric body 120.
There are two rectangular electrode notches 24 larger than the area of the outer surface of the
It is narrower by the area of

Lead wires 131 and 1 are connected to the electrodes 121 and 122.
32 are connected to each other, and information signals are applied to the inner and outer surfaces of the cylindrical piezoelectric body 120.

As described above, the piezoelectric element 12 as explained in FIGS. 1(a) and 1(b) is connected to the nozzle pipe 1 as shown in FIG.
For the three nozzle heads 1 adhered to the #1, the relationship between the value 'Vd of the information signal and the ejection speed V3 of the ink droplets 6, that is, the characteristic is 1. For example, the #A$ characteristic L1.1 as shown in FIG. Good characteristics L2. The case of defective characteristic L3 will be explained.

For convenience of explanation, the nozzle head whose characteristics are standard characteristic Ls will be referred to as nozzle head 1-1, the nozzle head whose characteristics are good characteristic L2 will be referred to as nozzle head 1-2, and the nozzle head whose characteristics are good characteristic L2 will be referred to as nozzle head 1-2. The nozzle pipe L3 is written as rad 1-3, respectively.

In this case, use nozzle Rad 1-1 as is,
The good characteristic L2 of the nozzle head 1-2 and the bad characteristic L3 of the nozzle head 1-3 are brought close to the standard characteristics of the nozzle head 1-1.

That is, the nozzle head 1-2 connects the electrode narrow portions 23 provided at two locations of the electrode 122 of the piezoelectric element 12 with the dotted line 25.
Cut at both locations.

As a result, the electrode 122 has a portion where the circumferential length of the cylinder existing between the two electrode notches 24 is the interval Ws, and a portion where the circumferential length of the cylinder is Wx+W2. The parts are electrically separated.

Although not shown in FIG. 4(b), the length of the lead wire 132 in the circumferential direction of the cylinder of the electrode 122 is W 1 +W x
Since the electrode 122 is connected to a certain portion, the area of the electrode 122 is reduced. Therefore, in order to generate liquid pressure in the ink 21 in the nozzle pipe 11 by the piezoelectric element 12 whose area of the electrode 122 is reduced, and to eject the ink particles 6 at the ejection speed vo by the liquid pressure, it is necessary to connect the electrode 121 and the electrode 122. It is necessary to increase the value v2 of the information signal 9 applied to the value v2 to bring it closer to the value ■1.

That is, by narrowing the area of the electric current t'M122, the characteristics of the nozzle Rad 1-2 become worse and the good characteristics L
2 is close to the standard characteristic L1. This is Rad1 to the nozzle.
This is because the effective width of the piezoelectric element 12 of -2 has become narrower.
The effective width is the area of the electrode 122, that is, the piezoelectric element 12
is proportional to the length in the circumferential direction of the cylinder, so if the effective width is expressed by the above length, the nozzle in this case has a radius of 1 rad.
The effective width of the piezoelectric element 12 of −2 is initially W 1+ W z
+ W s, but by cutting the two narrow electrode parts 23 of the electrode 122, the effective width becomes narrower and W
It became 1+W2.

Incidentally, the effective width of the piezoelectric element 12 of the nozzle radius 1-1 is V/z +Wz +Wa.

In addition, the nozzle head 1-3 has the electrode notches 24 provided at two locations on the electrode 122 coated with, for example, a conductive material.
The area of the electrode 122 is increased. Thereby, the ink particles 6 can be ejected at the ejection speed vo using the information signal 9 having a value smaller than the value v3. That is, electrode 1
By widening the area of 22, the rad 1-
The characteristics of No. 3 are improved, and the defective characteristic L8 becomes close to the standard characteristic L1. This is because the initial effective width W1+W2 +Wδ of the piezoelectric element 12 of the nozzle rod 1-3 becomes wider by applying a conductive material to the two electrode notches 24 of the electrode 122, and becomes W1+Wx This is because it became +W a+2Q. In this case, if the degree of the defective characteristic L3 of the nozzle head 1-3 is slight, the conductive material may be applied to only one of the two electrode notches 24. The effective width of the piezoelectric element 12 of the head 1-3 is Ws+W2+Wa+n.

In this embodiment, it has been explained that the electrode cut portions 24 are provided at two locations in the electrode 122, but three or more locations may be provided.

Furthermore, in this embodiment, the electrode notch 24 of the electrode 122
Although the shape of the electrode notch 24 has been described as being rectangular, the shape of the electrode notch 24 is not limited to the rectangular shape.

For example, square, triangular, bicircular, and elliptical shapes.

etc. may be used.

Although FIG. 1B shows that the electrode narrow part 23 is provided at the left end of the electrode 122, it is not limited to the left end, but can be provided at the right end or center of the electrode 122.

etc. may be provided.

〔Effect of the invention〕

According to the present invention, the effective widths of the piezoelectric elements of the plurality of nozzle heads can be adjusted, so that the characteristics of the plurality of nozzle heads can be made uniform. Therefore, since there is no difference in the magnitude of the information signals applied to multiple nozzle heads, there is no need for an adjustment circuit that adjusts the information signals according to the characteristics of each of the multiple nozzle heads, and the printer is It has the effect of not becoming large and expensive.

[Brief explanation of drawings]

Fig. 1 is an axial cross-sectional view of a cylindrical piezoelectric element of the present invention and a plan view of the electrodes on the cylindrical outer surface of the piezoelectric element, Fig. 2 is a configuration diagram of a nozzle head of the present invention, and Fig. 3 is a diagram showing the structure of the nozzle head of the present invention. A schematic diagram of a multi-nozzle inkjet printer, FIG. 4 is a diagram showing the relationship between the value of the information signal and the ejection speed of ink particles,
FIG. 5 is a diagram showing the characteristics of the nozzle head. 1.1 c, 1m, 1 y, 1 b-nozzle head, 2
...Carrier base, 3c, 3m, 3y, 3b...
Fixture, 4, 5...Rail, 6, 6c, 6m, 6y
+6b... Ink particle, 7... Recording body, 8c, 8m
. 8y, 8b... image resemblance, 9... information signal, 10...
nozzle. 11... Nozzle pipe, 12... Piezoelectric element, 13...
・・Ink supply tube, 14・・Filter, 15・
... Orifice, 16... Adhesive, 17.17',
18°18'...Side, 19...Edge, 20...Ink tank, 21...Ink, 22...Gap, 23
... Electrode narrow part, 24 ... Electrode notch, 25 ...
Dotted line, 120...Piezoelectric body, Figure 51 1't'B - 11 electric + 2 Figures

Claims (1)

[Claims] 1. An electromechanical conversion means is provided in the nozzle, an information signal is applied to the electrode of the electromechanical conversion means to generate a liquid pressure in the ink inside the nozzle, and the liquid pressure causes the nozzle to move. In an inkjet recording head that records information by ejecting the ink particles from the electrode, an electrode notch and an electrode narrowing part are provided in the electrode, and a new electrode is formed in the electrode notch and connected to the electrode. Inkjet recording characterized in that the area of the electrode is increased by increasing the area of the electrode, or the area of the electrode is decreased by cutting a narrow part of the electrode to separate a part of the electrode from the electrode. head.