JPH04290751A - Ink jet printer head - Google Patents

Abstract

PURPOSE:To enhance the degree of integration of ink flow passages formed from ink grooves and to miniaturize a head by forming a piezoelectric actuator element from a laminate composed of three or more piezoelectric sheets having a large number of walls composed of a piezoelectric material and a large number of ink grooves formed from the adjacent walls composed of the piezoelectric material provided to the single surfaces thereof. CONSTITUTION:A piezoelectric actuator element 16 is constituted of a laminate consisting of piezoelectric sheets 11a, 11b having a large number of walls 13 composed of a piezoelectric material and a large number of ink grooves 14 formed by the adjacent walls 13 provided to the single surface thereof and piezoelectric sheets 12a, 12b having a large number of walls 13 composed of a piezoelectric material and a large number of ink grooves 14 formed from the adjacent walls 13 provided to both surfaces thereof. The laminate is formed by mutually bonding the opposed surfaces of the walls composed of the piezoelectric material formed to the respective piezoelectric sheets. Driving electrodes 15 are formed to both side surfaces of the walls composed of the piezoelectric material and the pressure chambers of the ink flow passages formed from two ink grooves opposed in the laminating direction are arranged in a longitudinal and lateral matrix state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer head, and more particularly to the structure of a piezoelectric actuator element constituting the ink jet printer head and the structure of ink jet holes on an ink nozzle plate.

0002

2. Description of the Related Art Conventionally, various methods have been considered for obtaining gradation control means in non-impact type ink jet printers that utilize the deformation of piezoelectric actuator elements due to voltage application to eject ink. One of the most effective methods is to change the size of the ink droplets that are ejected. A specific method is to change the size of the ink droplet by controlling the magnitude of the applied voltage (that is, by controlling the control side).
Methods of changing the size of ink droplets by changing the size of ink ejection holes have been considered and put into practice.

0003

[Problems to be Solved by the Invention] However, the method using control on the control side has the problem that when the size of the ink jet hole is the same, the range in which the size of the ink droplet can be changed is small, and the control method There was a problem in that it required a complicated circuit, resulting in high costs.

Furthermore, although the method of changing the size of ink droplets by changing the size of the ink ejection holes is very effective as a means of gradation control, conventional inkjet printer heads using piezoelectric actuator elements are In many cases, a separate piezoelectric actuator element is used for each ink ejection hole, and as the number of ink ejection holes increases, the size of the head has to be increased.

The present invention has been made to solve the above-mentioned problems, and has excellent gradation controllability.
An object of the present invention is to provide an inkjet printer head that is small and has excellent integration of ink ejection holes.

[0006]

[Means for Solving the Problems] In order to achieve this object, the inkjet printer head of the present invention has a plurality of ink grooves formed by a plurality of walls that undergo shear deformation on at least one side according to an input signal. A piezoelectric actuator element constituted by a laminate formed by laminating piezoelectric sheets, and a large number of inks formed with at least two or more sets of different diameters, provided in parallel to the lamination direction of the piezoelectric actuator element. It is equipped with an ink nozzle plate having ejection holes.

[0007]

[Operation] In the inkjet printer head of the present invention having the above configuration, the piezoelectric wall is provided with driving electrodes on both sides thereof, so that voltage is turned on and off in response to input signals. Shear deformation occurs without dimensional change in the height direction of the wall. At this time, the volume of the multiple ink grooves formed by adjacent walls of the piezoelectric material changes as the walls of the piezoelectric material deform, and as the ink fluid pressure changes, the ink droplets from the ink jet holes Injection takes place. The inkjet printer head of the present invention is formed of a laminate including a plurality of walls made of piezoelectric material and a piezoelectric sheet having at least one side formed with a plurality of ink grooves formed by adjacent walls of the piezoelectric material. Since a piezoelectric actuator element is used, ink flow paths (pressure chambers) formed by walls of piezoelectric material and ink grooves are arranged in a matrix in the lateral direction and stacking direction of the piezoelectric actuator element. The ink ejection holes on the ink nozzle plate corresponding to the ink flow paths arranged in the horizontal direction can be used as one ink ejection hole group to form substantially one line of dots. Furthermore, since the ink ejection holes on the ink nozzle plate provided parallel to the stacking direction are formed with at least two sets of different diameters, it is possible to eject ink droplets with different diameters. Can be done.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic front view of the piezoelectric actuator element of this embodiment, and FIG. 2 shows a schematic front view of an ink nozzle plate provided with ink ejection holes. Further, FIG. 3 shows a schematic configuration diagram showing the positional relationship between the ink nozzle plate and the piezoelectric actuator element.

The piezoelectric actuator element 16 has a thickness of 0.6 mm and has a plurality of piezoelectric walls 13 on one side and a plurality of ink grooves 14 formed by adjacent walls of the piezoelectric material.
piezoelectric sheets 11a, 11b and 0.8 mm thick piezoelectric sheets 12a, 12b, each having a large number of piezoelectric material walls 13 on both sides and a large number of ink grooves 14 formed by adjacent walls of the piezoelectric material. It is composed of a laminate. The piezoelectric material walls and ink grooves formed on each piezoelectric sheet have a width dimension of 0.
．． 2 mm, and the height dimension (depth dimension) is 0.2 mm. Lamination is performed by bonding the opposing top surfaces of the walls of piezoelectric material formed on each piezoelectric sheet. Drive electrodes 15 are formed on both sides of the piezoelectric material wall. Ink channels (pressure chambers) formed by two ink grooves facing each other in the stacking direction are arranged in a vertical and horizontal matrix.

The ink nozzle plate 25 shown in FIG. 2 is formed of an ink ejection hole 21a having a diameter of 0.03 mm corresponding to the positional relationship of the ink flow path formed by the piezoelectric sheets 11a and 12a, and piezoelectric sheets 12a and 12b. An ink jet hole 21b with a diameter of 0.06 mm corresponds to the positional relationship of the ink flow path formed by the piezoelectric sheets 12b and 11b, and a diameter of 0.12 m corresponds to the positional relationship of the ink flow path formed by the piezoelectric sheets 12b and 11b.
m ink ejection holes 21c. Ink injection hole 2
1a, 21b, and 21c are divided into groups of ink ejection holes corresponding to ink flow paths spaced apart by one, and are offset by a necessary dimension in the stacking direction to form each group of ink ejection holes. 22a and 22b represent two sets of ink jet holes 21a, 23a and 23b represent two sets of ink jet holes 21b, and 24a and 24b represent two sets of ink jet holes 21c.
It represents one group. The piezoelectric actuator element 16
An ink nozzle plate 25 is adhered to the front surface of the inkjet printer head through a strip sealing material.

The operation will be explained below. Piezoelectric sheet 1
1 and 12 are all polarized in the thickness direction. The polarization directions of the piezoelectric sheets are 11a and 12a, 12a and 12b, 1
2b and 11b are opposite directions in the stacking direction. Therefore, when an electric field is applied between the drive electrodes 15 provided on both sides of the piezoelectric wall 13, the polarization direction and the applied electric field direction are perpendicular to each other, causing shear deformation (thickness (also called slip deformation). When the applied electric field is removed (charge stored in the piezoelectric material is discharged), the walls of the piezoelectric material return to their original state. At this time, when focusing on one ink flow path, the volume increases and decreases, causing a change in the pressure of the ink liquid, and ink droplets are ejected. However, when focusing on an ink flow path adjacent to the ink flow path where ink droplets are ejected, the change in volume is necessarily opposite to that of the ink flow path where ink droplets are ejected. Therefore, ink droplets cannot be ejected from corresponding ink ejection holes in adjacent ink flow paths at the same time. As a method to substantially eliminate this problem, the ink ejection holes are divided into sets of ink ejection holes corresponding to ink flow paths separated by one space, and formed offset by a necessary dimension in the stacking direction. In other words, if we consider the paper feeding direction during printing as the stacking direction, the ink jet hole sets 22a and 22b
Both can be used to form dots on one line. In the case of this embodiment, the pitch interval of the ink ejection holes on one line is substantially 0.4 mm, allowing for considerably high integration.

The inkjet printer head of this embodiment has a set of three types of ink ejection holes having different diameters that are highly integrated within a thickness of 2.8 mm. Therefore, the size of dots used for printing can be freely selected from three types of dot sizes. This is an effective means for tone control. In reality, the size of printed dots cannot be accurately controlled solely by the size of the ink ejection holes. In the case of this embodiment as well, it is necessary to control the voltage and discharge time on the control side. However, the control on the control side only needs to be performed for each of the three sets of ink ejection holes 22, 23, and 24, so the circuit is not so complicated and the cost increase is also small.

[0014]

As is clear from the above explanation, in the inkjet printer head of the present invention, the piezoelectric actuator element constituting the head has a plurality of walls of piezoelectric material that undergoes shear deformation according to an input signal, and Since it is composed of a laminate made up of three or more piezoelectric sheets each having a large number of ink grooves formed by adjacent walls of the material formed on at least one side, the degree of integration of the ink channels formed by the ink grooves is The head can be made smaller.

Furthermore, since the diameters of the ink jetting holes on the ink nozzle plate provided parallel to the stacking direction are formed with at least two sets of different diameters, ink droplets with different diameters can be jetted. It is possible to supply an inkjet printer head with excellent gradation.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing the configuration of a piezoelectric actuator element of this embodiment.

FIG. 2 is a schematic front view showing the configuration of the ink nozzle plate of this embodiment.

FIG. 3 is a schematic configuration diagram of an inkjet printer head of this embodiment.

[Explanation of symbols]

11 Piezoelectric sheet 12 Piezoelectric sheet 13 Piezoelectric material wall 14 Ink groove 16 Piezoelectric actuator element 21 Ink injection hole 25 Ink nozzle plate

Claims (1)

[Claims] Claim 1: In an inkjet printer head that utilizes shear deformation of a piezoelectric material to eject ink droplets, a number of ink grooves defined by a number of walls that undergo shear deformation are laminated in accordance with an input signal. a piezoelectric actuator element formed of a laminate in which three or more piezoelectric sheets are stacked on at least one of the surfaces;
An inkjet printer head comprising an ink nozzle plate which is arranged parallel to a stacking direction and has at least two sets of ink ejection holes having different diameters.