JPH05318727A - Method for driving of ink jet type printing head - Google Patents

Abstract

PURPOSE:To obtain variation in a volume of an ink chamber for discharge of ink in high energy conversion efficiency by a method wherein a wall opposed to an elastic wall of an ink chamber is displaced in an opposite phase to displacement to the ink chamber via the elastic wall. CONSTITUTION:An ink chamber 18 is composed of an elastic wall 16a, and a cover block 17 which forms a parition wall 17a dividing individually a plurality of ink chambers 18 and a nozzle. Then, a piezoelectric element 12a and a piezoelectric element 12b are arranged by corresponding one to one to each elastic wall and each parition wall 17a. The elastic wall 16a and the partition wall 17a are displaced in an opposite phase with respective piezoelectric elements 12a, 12b to reduce volume of the ink chamber 18 and ink is discharged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head for an ink jet printer which forms an ink image on a recording medium such as recording paper by ejecting ink droplets according to a print signal.

[0002]

2. Description of the Related Art As shown in Japanese Patent Publication No. 3-258550, a recording head of an ink jet printer, which ejects ink droplets in response to a print signal, has one end of a piezoelectric element fixed to a base. Is brought into contact with an elastic wall that forms the ink chamber and a partition that individually divides the ink chamber.

FIG. 6 shows an exploded perspective view of a conventional ink jet print head.

In FIG. 1, a comb-shaped piezoelectric element 12 is provided on a base 11. One side surface of the piezoelectric element 12 is electrically connected to the signal electrode 13 on the fixed base 11,
The other side surface is electrically connected to the common electrode 14, each electrode 13
And 14 are connected to the drive circuit 15.

A cover block 17 is disposed on the side surface of the piezoelectric element 12 which is not fixed, with an elastic wall member 16 interposed therebetween. An ink chamber 18 and a nozzle 19 are integrally formed between the cover block 17 and the elastic wall member 16.

A drive circuit 1 from an external control circuit (not shown)
A voltage is selectively applied to any of the signal electrodes 13 via 5. The signal is simultaneously applied to the piezoelectric element 12a that comes into contact with the ink chamber 18 for ejecting ink and the piezoelectric elements 12b and 12b that come into contact with the partition wall 17a that forms the ink chamber 18 and divides the adjacent ink chamber 18. Therefore, as shown in FIG. 7, the corresponding piezoelectric elements 12b, 12b
The piezoelectric effects of a and 12b are displaced in the same direction, and a dynamic pressure is generated in the ink in the ink chamber 18.

[0007]

The conventional ink jet type print head described above has piezoelectric elements 12b, 12a, 1a.
A signal voltage is simultaneously applied to 2b and the ink chamber 18 and the partition wall 1
It is configured to apply pressure to 7a at the same time. Therefore, as shown in FIG. 7 which is a sectional view taken along the line AA of FIG. 4, there is a problem that the elastic wall member 16 is displaced in the same direction and the volume change of the ink chamber 18 for ink ejection cannot be obtained. .. Similarly, as shown in FIG.
There is a problem in that ink cannot be supplied because the pressures on a and 12b are released at the same time.

Further, in order to obtain the volume change of the ink chamber 18 sufficient for ink ejection in such a structure,
There is a problem that higher electric energy must be applied to the piezoelectric element 12a with respect to the piezoelectric element 12b.

Therefore, an object of the present invention is to provide an ink jet type print head driving method and driving means which can effectively utilize such unnecessary driving of the piezoelectric element and can enhance the efficiency of energy conversion into ink ejection. Especially.

[0010]

According to the method of driving an ink jet type print head of the present invention, an ink chamber comprises an elastic wall, a partition wall for dividing the ink chamber individually, and a wall forming a nozzle, and the ink chamber faces the elastic wall. The ink discharge pressure is generated by displacing the wall in reverse phase. Further, the ink jet type print head driving means, in the ink jet type print head, arranges piezoelectric elements on the elastic wall and the partition wall in a one-to-one correspondence, and arranges the elastic wall and the partition wall by the piezoelectric element. It is characterized in that it is displaced in the opposite phase.

[0011]

EXAMPLES The ink jet print head according to the present invention will be described in detail below with reference to examples. FIG. 3 is a perspective view of an ink jet type print head using displacement of a piezoelectric element in the direction of an applied electric field as one embodiment of the present invention. 1 and 2
FIG. 4 is a partial cross-sectional view taken along the line BB of FIG. 3, which is a diagram for explaining a driving method and a driving means. FIG. 4 is an exploded perspective view of an ink jet type print head utilizing displacement of a piezoelectric element in a direction perpendicular to an applied electric field as another embodiment of the present invention. FIG. 5 shows C looking up from the lower right of the paper of FIG. 4 to the upper left.
It is a C line partial cross section.

In these drawings, reference numeral 17 is a cover block, which together with the elastic wall member 16 includes the ink chamber and the nozzle 1.
9 is formed. The convex portion of the cover block 17 serves as a partition wall 17a that divides the ink chambers 18, 18 into individual partitions. A portion of the elastic wall member 16 that is not fixed to the partition wall 17a that forms the ink chamber 18 becomes the elastic wall 16a that transmits the ink dynamic pressure to the ink chamber 18. The base 1 is attached to each of the positions where the ink chamber 18 and the partition wall 17a come into contact with each other via the elastic wall member 16.
The ink jet print head is configured by arranging the piezoelectric elements 12a and the piezoelectric elements 12b fixed by 1 in one-to-one correspondence.

The present invention will be described with reference to FIG. The piezoelectric element 12 is provided with an electrode 23 that is fixedly connected to and electrically connected to the signal electrode 13 of the base 11 on one side surface, and is fixed and electrically connected to the common electrode 14 (see FIG. 6) on the other side surface. The electrode 24 is provided. The electrode 23 and the electrode 24 are provided commonly to the piezoelectric element 12a and the piezoelectric element 12b and are connected to the drive circuit 15 (see FIG. 6). The piezoelectric element 12a and the piezoelectric element 12b are arranged in parallel on the base 11.

The elastic wall member 1 is provided on the electrode 24 side of the piezoelectric element 12.
6, the cover block 17 is fixed in order. Grooves and partition walls 17 that form ink chambers 18 in the cover block 17
The piezoelectric element 12a and the piezoelectric element 12b are fixed to each other via the elastic wall member 16 while having the convex portions of a.

The piezoelectric element 12 has a structure divided into a comb shape, and a plurality of piezoelectric elements 12b and 12a are alternately formed in parallel. These are processed by, for example, a dicing saw, a wire saw, or the like, and a full cut for cutting the piezoelectric element 12 to the surface of the base 11 or a half cut that does not reach the base 11 is performed. The material of the piezoelectric element 12 is lead zirconate titanate (PZT) here, and either a single layer piezoelectric element or a laminated piezoelectric element can be used.

In this embodiment, the signal electrode 13 is formed by fixing the piezoelectric element block to the base 11 and then by the cutting means, the base 11 is formed.
By cutting to the surface, each piezoelectric element 12b, 12a,
It is formed as an independent electrode together with the division of 12b. The common electrode 14 electrically connects a thin film such as a copper foil to a part of the electrodes 24 of the plurality of piezoelectric elements 12.

The cover block 17 is integrally formed with a groove forming an ink chamber 18 and a nozzle 19 (see FIG. 4) communicating with the groove. The cover block 17 can be easily formed by injection molding of plastic, for example.
As another technique, it can be formed by etching using a photosensitive resin, or by separately forming the partition wall 17a of the cover block 17 and other portions by pressing, etching, or the like and fixing them.

Next, the operation of the print head of this embodiment will be described.

The ink ejection operation will be described with reference to FIG. A signal is applied to the signal electrode 13 from a drive circuit 15 (not shown) and is transmitted to one electrode 23 of the piezoelectric element 12. The other electrode 2 of the piezoelectric element 12 connected to the common electrode 14.
Since 4 is a common potential, a piezoelectric effect is generated by a change in potential at the electrode 23 due to signal transmission, and the piezoelectric element 12 is mounted on the base 1
It is displaced in the direction of the ink chamber 18 with reference to 1. The driving method according to the present invention will be described based on this operation. As shown in FIG. 1, when the piezoelectric element 12a displaces the elastic wall 16a fixed thereto to press the ink chamber 18, the piezoelectric element 12b releases the pressing of the cover block 17 fixed via the elastic wall member 16. The operation of displacing the ink in the direction is combined to cause a decrease in the volume of the ink chamber 18 to generate an ink ejection dynamic pressure and eject the ink. In the next operation, as shown in FIG. 2, the piezoelectric element 12a displaces the elastic wall 16a to which the piezoelectric element 12a is fixed in the pressing release direction, and the piezoelectric element 12b is fixed via the elastic wall member 16 to the cover block. The operation of displacing 17 in the pressing direction is integrated, and the volume of the ink chamber 18 is changed to increase so that the ink supply dynamic pressure is generated to fill the ink chamber 18. The above-described operation is performed by selectively transmitting a signal to the ink chamber 18 communicating with the nozzle 19 required for printing and the piezoelectric elements 12b, 12a, 12b contacting the partition wall 17a forming the ink chamber 18 as a unit. The image can be formed on a medium such as paper.

Another embodiment of the present invention will be described with reference to FIG. The driving uses displacement of the piezoelectric element 12 in a direction perpendicular to the applied electrolysis direction. One side of the piezoelectric element 12 in the longitudinal direction in the figure is fixed to the base 11, and the half of the non-fixed tip is elastic. It is fixed to the wall 16a. The base 11 is provided with the signal electrode 13, and through the lead frame 25,
Although not shown, a voltage controlled by the drive circuit 15 is applied to the piezoelectric element 12.

A schematic structure will be described with reference to FIG. The ink is supplied to the ink chamber 18 through the ink supply pipe 31, the connection port 32, and the ink communication port 33 in the elastic wall member 16. The cover block 17 is composed of a nozzle substrate 17b forming a nozzle 19 and a partition wall 17a, and is fixed to the elastic wall member 16 in order to the partition wall 17a nozzle substrate 17b. The piezoelectric element 12 and the elastic wall member 16 are provided with a guide member 40.
Is more accurately positioned.

The structure will be described in more detail with reference to FIG. FIG. 7 shows a plurality of piezoelectric elements 1 arranged in parallel (X direction in FIG. 8).
2 is a partial cross-sectional view when 2 is cut in the X direction from the center. FIG. In the piezoelectric element 12, one electrode 23 and the other one electrode 24 face each other. The electrode 23 is fixed and electrically connected to the signal electrode 13 on the base 11 at the same time. Other electrode 2
4 are connected by a common electrode 14 so that a plurality of them have the same potential. The nozzle substrate 17b, the partition wall 17a, and the elastic wall member 16 have a laminated structure in which they are adhered and fixed to each other.
Reference numeral 2 denotes a piezoelectric element 12a and a piezoelectric element 1 at positions where they contact the ink chamber 18 and the partition wall 17a, respectively, via the elastic wall members 16.
2b is provided.

The partition wall 17a is formed by etching glass.
It can be made by laminating thin metal plates, exposing and forming a photosensitive resin, and injection molding a resin. The nozzle substrate 17b covering the upper surface of the partition wall 17a has a nozzle 19 formed in each of the plurality of ink chambers 18 by press working.
It is made of a stainless steel plate of about 1 mm. Nozzle substrate 17b
Can also be made by nickel electroforming. The elastic wall member 16 that covers the lower surface of the partition wall 17a is
A thin metal plate formed to a thickness of 5 μm or less by an electroforming method of nickel is used, and this may be replaced with a resin such as a film.

With the print head formed as described above, the displacement of the piezoelectric element 12a is assisted by the antiphase displacement of the piezoelectric element 12b, so that the volume change of the ink chamber 18 is easily caused. A feature of the present embodiment is that the elastic wall 16a portion and the nozzle substrate 17b portion are displaced in opposite phases in the present embodiment in which the ink chamber 18 is sandwiched, so that the volume change of the ink chamber 18 can be efficiently obtained.

[0025]

As described above, in the ink jet type print head of the present invention, it is not necessary to displace the piezoelectric element unnecessarily in response to the ink ejection pressure, and therefore, it is possible to increase the volume of the ink chamber. Does not need a lot of electrical energy. That is, the energy conversion efficiency can be increased.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a driving method of the present invention.
(Ink ejection operation)

FIG. 2 is a sectional view showing an embodiment of a driving method of the present invention.
(Ink supply operation)

FIG. 3 is a perspective view showing the structure of an embodiment of the present invention.

FIG. 4 is an exploded perspective view illustrating the configuration of the embodiment.

FIG. 5 is a partial cross-sectional view illustrating another embodiment of the present invention.

FIG. 6 is an exploded perspective view showing the structure of an embodiment of the present invention and the prior art.

FIG. 7 is a partial cross-sectional view illustrating a problem of the conventional technique. (Ink ejection operation)

FIG. 8 is a partial cross-sectional view illustrating a problem of the conventional technique. (Ink supply operation)

[Explanation of symbols]

 Reference Signs List 11 base 12 piezoelectric element 13 signal electrode (on base) 14 common electrode (on base) 15 drive circuit 16 elastic wall member 16a elastic wall 17 cover block 17a partition wall 17b nozzle substrate 18 ink chamber 19 nozzle 23 signal electrode (piezoelectric) Element top) 24 Common electrode (on piezoelectric element) 25 Lead frame 31 Ink supply pipe 32 Connection port 33 Ink communication port 40 Guide member

Claims (2)

[Claims] 1. An ink jet print head in which an ink chamber comprises at least an elastic wall, a partition for dividing the ink chamber individually and a wall forming a nozzle, and the elastic wall is displaced by a piezoelectric element to eject ink. 3. The method for driving an inkjet print head according to claim 1, wherein the elastic wall forming the ink chamber and the wall surface other than the elastic wall forming the ink chamber are displaced in opposite phases. 2. The ink jet print head driving method drives an ink jet head in which the piezoelectric elements are arranged in a one-to-one correspondence with the ink chambers and the partition walls with the elastic wall interposed therebetween. The method for driving an inkjet print head according to claim 1.