DROPLET DISCHARGING HEAD AND DROPLET DISCHARGING DEVICE

Abstract

A droplet discharging head includes: a plurality of containing chambers provided in parallel to one another with partition walls interposed therebetween, each containing chamber, partitioned and formed by each partition wall and a member with a vibration plate, being communicated with a nozzle and containing a liquid material; a main piezoelectric element bonded onto an outer surface of the vibration plate of the containing chamber; and a sub-piezoelectric element bonded to a portion corresponding to the partition wall on a side of the main piezoelectric element of the containing chamber. The main piezoelectric element and the sub-piezoelectric element are structured so that one of the main piezoelectric element and the sub-piezoelectric element expands, when the other contracts. The vibration plate is displaced, altering a volume of the containing chamber for a droplet of the liquid material to be discharged from the nozzle. The main piezoelectric element and the sub-piezoelectric element each have a piezoelectric material layer with piezoelectricity having at least one layer, and at least one pair of electrode layers sandwiching the piezoelectric material layer. The piezoelectric material layer and the electrode layers are alternately layered in the thickness direction of the vibration plate. The piezoelectric material layer odd-numbered from a side of the containing chamber in the main piezoelectric element has an opposite polarization direction to that of the piezoelectric material layer odd-numbered from the side of the containing chamber in the sub-piezoelectric element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.

FIG. 1 is a view showing the schematic structure of a droplet discharging device according to a first embodiment of the invention.

FIG. 2 is a block diagram showing the structure of a control system of the droplet discharging device shown in FIG. 1.

FIG. 3 is a perspective view showing the schematic structure of part of a droplet discharging head provided in the droplet discharging device shown in FIG. 1.

FIG. 4 is an exploded perspective view of the droplet discharging head shown in FIG. 3.

FIG. 5 is a sectional view taken along the line A-A in FIG. 3.

FIGS. 6A and 6B are perspective views showing the schematic structures of piezoelectric elements provided in the droplet discharging head shown in FIG. 3.

FIGS. 7A to 7C are views for explaining operations of the droplet discharging head shown in FIG. 3.

FIGS. 8A and 8B are perspective views showing the schematic structures of piezoelectric elements provided in the droplet discharging head according to a second embodiment of the invention.

Claims

1. A droplet discharging head, comprising: a vibration plate;a partition wall attached to a first surface of the vibration plate, the partition wall defining a plurality of containing chambers, each of the plurality of containing chambers being configured to hold a liquid material and to eject the liquid material from a nozzle;a first piezoelectric element attached to a second surface of the vibration plate, the first piezoelectric element overlapping with one of the plurality of containing chambers, the first piezoelectric element including a plurality of first piezoelectric material layers and a plurality of first electrode layers, the plurality of first piezoelectric material layers and the plurality of a first electrode layers being laminated alternately; anda second piezoelectric element attached to the second surface of the vibration plate, the second piezoelectric element being adjacent to the first piezoelectric element, the second piezoelectric element overlapping with a first portion of the partition wall, a first part of the vibration plate being interposed between the second piezoelectric element and the first portion of the partition wall, the second piezoelectric element including a plurality of second piezoelectric material layers and a plurality of second electrode layers, the plurality of second piezoelectric material layers and the plurality of a second electrode layers being laminated alternately, a polarization direction of odd-numbered one of the plurality of first piezoelectric material layers being opposite to a polarization direction of odd-numbered one of the plurality of second piezoelectric material layers.

2. The droplet discharging head according to claim 1, a polarization direction of odd-numbered one of the plurality of first piezoelectric material layers being opposite to a polarization direction of even-numbered one of the plurality of first piezoelectric material layers.

3. The droplet discharging head according to claim 1, a displacement amount of the first piezoelectric element at a first voltage being configured to be larger than a displacement amount of the second piezoelectric element at a second voltage, the first voltage being equal to the second voltage.

4. The droplet discharging head according to claim 1, a number of the plurality of second piezoelectric material layers in the second piezoelectric element being smaller than a number of the plurality of first piezoelectric material layers in the first piezoelectric element.

5. The droplet discharging head according to claim 1, an area of an overlapping region of mutually adjacent ones of the plurality of a second electrode layers in the second piezoelectric element being smaller than an area of an overlapping region of mutually adjacent ones of the plurality of a first electrode layers in the first piezoelectric element.

6. The droplet discharging head according to claim 1, further comprising: a substrate, the first piezoelectric element being interposed between the substrate and the vibration plate, and the second piezoelectric element being interposed between the substrate and the vibration plate.

7. The droplet discharging head according to claim 1, further comprising: a third piezoelectric element attached to the second surface of the vibration plate, the third piezoelectric element being adjacent to the first piezoelectric element, the first piezoelectric element being disposed between the second and third piezoelectric element, the third piezoelectric element overlapping with a second portion of the partition wall, a second part of the vibration plate being interposed between the third piezoelectric element and the second portion of the partition wall, the third piezoelectric element including a plurality of third piezoelectric material layers and a plurality of third electrode layers, the plurality of third piezoelectric material layers and the plurality of third electrode layers being laminated alternately, a polarization direction of odd-numbered one of the plurality of first piezoelectric material layers being opposite to a polarization direction of odd-numbered one of the plurality of third piezoelectric material layers.

8. A droplet discharging device comprising the droplet discharging head according to claim 1.

9. A droplet discharging device, comprising: the droplet discharging head according to claim 1; anda drive unit for driving each of the first piezoelectric element and the second piezoelectric element, the drive unit being coupled to each of the first piezoelectric element and the second piezoelectric element so as to simultaneously apply an voltage with an identical waveform to each of the first piezoelectric element and the second piezoelectric element.