CN212267015U - Piezoelectric ink jet printing device with outer surface electrode layer - Google Patents

Abstract

A piezoelectric ink jet printing device includes a substrate and a piezoelectric plate. A pair of staggered rows of drop ejectors are disposed on the substrate in a row direction. Each drop ejector includes an orifice in fluid communication with a pressure chamber bounded by a sidewall. The first surface of the piezoelectric plate abuts against the pressure chamber. An electrode layer is disposed on an opposite second outer surface of the piezoelectric plate. The electrode layer includes a signal line corresponding to each drop ejector in the staggered rows, and at least one common ground line connected to ground lines aligned along the side walls above each pressure chamber. Each signal line leads to a corresponding signal input pad disposed between the staggered rows. The common ground line extends in the row direction and leads to the return ground pads.

Description

Piezoelectric ink jet printing device with outer surface electrode layer

Technical Field

The utility model belongs to piezoelectricity inkjet printing field, more specifically relates to the structure of piezoelectricity inkjet printing device.

Background

Ink jet printing is typically accomplished with drop-on-demand or continuous ink jet printing. In drop-on-demand ink-jet printing, droplets are ejected onto a recording medium using a droplet ejector with a pressurizing (e.g., thermal or piezoelectric) actuator. Selectively activating the actuator causes a flying ink drop to be formed and ejected that passes through the space between the printhead and the recording medium and impacts the recording medium. The formation of the printed image is achieved by controlling the formation of each drop as required to print the desired image. The desired image may include any dot pattern corresponding to the image data. It may include graphical or textual images. It may also include a dot pattern or three-dimensional structure for printing the functional utility device if a suitable ink is used. The ink may comprise a colored ink, such as cyan, magenta, yellow or black. Alternatively, the ink may include a conductive material, a dielectric material, a magnetic material, or a semiconductor material for functional printing. The ink may also include biological, chemical, or medical materials.

During drop ejection, the movement of the recording medium relative to the printhead may be: holding the print head stationary while the recording medium advances past the print head as the droplets are ejected; or the recording medium may be held stationary while the printhead is moved. The former motion configuration is suitable if the array of drop ejectors on the printhead can cover the entire print region of interest across the width of the recording medium. Such printheads are sometimes referred to as pagewidth printheads. A second type of printer architecture is a carriage printer, in which the printhead drop ejector array is smaller than the extent of the print region of interest on the recording medium, and the printhead is mounted on a carriage. In the carriage printer, the recording medium is advanced by a given distance in the medium advance direction and then stopped. While the recording medium is stopped, the printhead, carrying orifices that are ejecting droplets, moves in a carriage scan direction that is substantially perpendicular to the media advance direction. After a print head mounted on the carriage simultaneously prints a strip of an image across the print medium, the print medium is advanced; then the direction of movement of the carriage is reversed; the printed image is thus formed band by band.

A drop ejector in a drop-on-demand ink jet printhead includes a pressure chamber having an ink inlet channel for providing ink to the pressure chamber and an orifice for ejecting a drop of ink out of the pressure chamber. In a piezoelectric ink jet printing device, a wall of a pressure chamber includes a piezoelectric element that deflects the wall to deform into the ink-filled pressure chamber when a voltage pulse is applied, thereby forcing ink through an orifice. The piezo inkjet has a significant advantage in chemical compatibility with various kinds of inks (including aqueous inks, solvent-based inks, and ultraviolet curable inks) and ink jettability, and has a function of ejecting ink droplets of different sizes by modifying an electric pulse.

Piezoelectric inkjet printing devices also have technical challenges that need to be addressed. Because the amount of piezoelectric displacement per volt of voltage is small, the piezoelectric chamber wall area must be much larger than the orifice area in order to eject a useful amount of fluid droplets, and therefore each drop ejector is relatively large. The width of each drop ejector in a row of drop ejectors is limited by the spacing of the rows of orifices. The result is that the length dimension of the pressure chamber is typically much larger than the width dimension. Printing applications requiring high resolution and high throughput printing require a large array of drop ejectors with closely spaced orifices. The staggered rows of orifices can fire dots on the recording medium at close distances with proper timing of the ejection of each row of drop ejectors. However, for many staggered rows, the size of the piezoelectric inkjet printing device becomes large.

Another challenge is that thermal inkjet printing devices typically include integrated logic and drive electronics to reduce the number of leads for the device, unlike piezoelectric inkjet printing devices which typically have individual leads per drop ejector that need to be connected to a drive circuit board. In order to be able to apply a voltage independently across the piezoelectric element of each drop ejector in order to eject a drop when required, two electrodes per drop ejector are required. These two types of electrodes are sometimes referred to as positive and negative electrodes, or as a single electrode and a common electrode.

Some types of piezoelectric inkjet printing devices are constructed with two types of electrodes on opposite surfaces of the piezoelectric element. In order to electrically interconnect the piezoelectric ink jet printing device to the driving circuit board, it is advantageous to provide both types of electrodes on the same outer surface of the piezoelectric element.

Us patent No. 5,255,016 discloses a piezoelectric ink jet printing device in which positive and negative comb-like electrodes are formed on the outer surface of a piezoelectric plate. The teeth of their comb extend across the entire width of the drop ejector, at least in some areas. A portion of the positive electrode extends along one edge of the piezoelectric plate and a portion of the negative electrode extends along the opposite edge of the piezoelectric plate. Each drop ejector has a separate piezoelectric plate, which makes it difficult to manufacture large arrays of closely spaced drop ejectors.

Us 6,243,114 discloses a piezoelectric ink jet printing device in which the common electrode on the outer surface of the piezoelectric plate is comb-shaped with one electrode tooth extending along each side wall of the pressure chamber and a central common electrode tooth extending along the length of the pressure chamber. Two individual electrodes extend along the length of the pressure chamber on either side of the central common electrode tooth.

U.S. patent No. 5,640,184 discloses a piezoelectric ink jet printing device in which pressure chambers of a row of orifices extend alternately in opposite directions from the row of orifices. The common electrode on the surface of the piezoelectric plate extends along the rows of orifices and has electrode teeth extending alternately in opposite directions on the side walls of the pressure chamber. Interleaved between the electrode teeth of the common electrode is a spaced array of individual electrodes that are located directly above the pressure chamber. When a voltage is applied to the individual electrodes, the piezoelectric plates are mechanically deformed in a shear mode into the corresponding pressure chambers, thereby causing ejection of ink droplets.

Chinese patent application publication No. 107344453a discloses a piezoelectric ink jet printing device, as shown in fig. 1 and 2. Figures 1 and 2 are taken from' 453, with some additional labels added to figure 1 for clarity. The substrate 100 comprises a first side 101 and an array of pressure chambers 110 is distributed over the first side 101. Each pressure chamber 110 is delimited by side walls 161 and 162. A channel 130 leads from the pressure chamber 110 to an orifice 132 provided on the second face 102 of the substrate 100. The pressure chamber 110 has a width W between the side walls 161 and 162. An ink tank 120 is fluidly connected to one end of each pressure chamber 110 to supply ink thereto. A damping structure 140 comprising a plurality of posts 141 is disposed in each pressure chamber 110 between the ink tank 120 and the channel 130. The actuating cover plate 200 includes a piezoelectric plate 210, and the piezoelectric plate 210 may be made of, for example, lead zirconate titanate (PZT) material. The first surface 211 of the piezoelectric plate 210 is bonded to the first side 101 of the substrate 100. An electrode layer 220 is disposed on the outer second surface 212 of the piezoelectric plate 210. The electrode layer 220 includes a positive electrode 221, the positive electrode 221 is disposed lengthwise over the pressure chamber 110; a negative electrode 222 is also included, the negative electrode 222 being disposed lengthwise over the side walls 161 and 162 between the pressure chambers 110. An ink inlet 230 extends through the piezoelectric plate 210 to direct ink from an external ink supply to the ink tank 120 in the substrate 100. The orifices 132 extend outward from the runners 131 in the silicon material layer 310, through the oxide layer 320 and the orifice layer 330 (fig. 2).

Although the prior art has been disclosed with piezoelectric ink jet printing devices having two types of electrodes on the outer surface of the piezoelectric plate, they require improvements in the configuration of the wire arrangement to facilitate electrical interconnection of the piezoelectric ink jet printing devices. In addition, there is also a need to improve the arrangement configuration of droplet ejectors on a piezoelectric inkjet printing device in a space-saving manner to achieve high-resolution and high-throughput printing.

SUMMERY OF THE UTILITY MODEL

According to one aspect of the present invention, a piezoelectric inkjet printing device includes a substrate and a piezoelectric plate. At least two rows of drop ejectors are staggered on the substrate such that each row is aligned along a row direction. Each droplet ejector includes a pressure chamber having a width W in the direction of the row. The pressure chamber sets up on the first face of base plate, is delimited by first side wall and second side wall along the direction of arranging. Each drop ejector also includes an orifice in fluid communication with the pressure chamber. The nozzle hole is provided in a nozzle hole layer on the second surface of the substrate. The piezoelectric plate has a thickness T between a first surface adjacent to the pressure chamber and an outer second surface opposite to the first surface. The electrode layer is disposed on the second face of the piezoelectric plate. The electrode layer includes a one-to-one signal line corresponding to each of the droplet ejectors in the at least two staggered rows, and at least one common ground line connected to the branch ground lines disposed along and aligned with the first side wall and the second side wall of each of the pressure chambers. Each signal line leads to a corresponding signal input pad disposed between staggered rows, where there is at least one pair of staggered rows. At least one common ground line extends in the row direction and leads to at least one ground return pad.

The utility model has the advantages of, the electric wire of piezoelectricity inkjet printing device and their corresponding connection pad structural configuration are favorable to compact and reliably electric intercommunication to be connected to on beating the head package. Another advantage is that the piezoelectric drop ejector is constructed in a space-saving manner and enables high printing resolution and high printing throughput.

Drawings

FIG. 1 shows an exploded schematic view of a prior art piezoelectric drop ejector array configuration;

FIG. 2 shows a cross-section of a single drop ejector of the type shown in FIG. 1;

FIG. 3 shows a cross-section of a portion of a piezoelectric plate and a corresponding portion of the substrate;

FIG. 4A shows a top view of three droplet ejectors in a substrate;

FIG. 4B shows a top view of the wires on the piezoelectric plate corresponding to the drop ejector shown in FIG. 4A;

FIG. 5 shows a top view of a single drop ejector and its corresponding electrical leads;

FIG. 6 illustrates a top view of a portion of a piezoelectric inkjet printing device in one embodiment;

FIG. 7 shows a top view of a masking layer with a window;

fig. 8 shows a top view of a portion of a piezoelectric inkjet printing device in another embodiment.

The drawings are for purposes of illustrating the concepts of the invention and may not be to scale. Identical reference numerals have been used, where possible, to designate identical features that are common to the figures.

Detailed Description

The present invention includes various combinations of the embodiments described herein. Reference to "a particular embodiment" and similar references means that a feature is present in at least one embodiment of the invention. Separate references to "one embodiment" or "a particular embodiment" and the like do not necessarily refer to the same embodiment or embodiments; however, unless explicitly stated or otherwise apparent to one skilled in the art, these embodiments are not mutually exclusive. The use of the singular or plural in referring to "a method" or "methods" and the like is not limiting. It is expressly noted that the use of "or" is not intended to be an exclusive meaning unless expressly stated otherwise or required by context. Words such as "above," "below," "in.. above," or "below" are intended to describe the positional relationship between features that lie in different planes, but it is understood that in one device orientation, a feature of one device lies "above" another feature, and if the device is turned upside down, a feature of the device will lie "below" the other feature.

Fig. 3 shows a cross-section of the piezoelectric plate 210 and the corresponding portion of the substrate 100 along the dashed line 3-3 of fig. 6. The thickness of the piezoelectric plate 210 is T. The substrate 100 includes a pair of pressure chambers 111 and 112, which extend outward from a central region. Each pressure chamber 111 and 112 includes a channel 130 leading to an orifice 132 disposed in an orifice layer 330. A bonding layer 270 is disposed on the first surface 211 of the piezoelectric plate 210. Bonding layer 270, for example, may be a polymeric adhesive. In the assembled piezoelectric printing apparatus 10 (fig. 6), the bonding layer 270 bonds the piezoelectric plate 210 to the first side 101 of the substrate 100. The electrode layer 220 is disposed on the outer second surface 212 of the piezoelectric plate 210. The electrode layer 220 includes signal lines 251 on the outer second surface 212 of the piezoelectric plate 210, the signal lines 251 extending over the pressure chambers 111 and 112 in the assembled device. The signal lines 251 lead to respective signal input pads 255. The electrode layer 220 also includes at least one common ground line 264.

Top view 4A shows three droplet ejectors 150 formed in a row on substrate 100 (fig. 3), each droplet ejector 150 comprising a pressure chamber 110 and an orifice 132. The orifices 132 (and drop ejectors 150) are aligned in the row direction 51, and adjacent orifices are spaced apart by a center-to-center pitch p. The pressure chamber 110 has a width W in the row direction 51 and is delimited by side walls 161 and 162, each side wall 161 and 162 having a wall width s, such that W + s is p. In order to provide a sufficiently large area of the pressure chamber 110, it is advantageous in many embodiments that W is larger than 0.8 p. In other words, s is typically less than 0.2 p. The orifice 132 is disposed near the first end 115 of the pressure chamber 110. In the example shown in fig. 4A, ink enters the pressure chamber 110 from the ink tank 120 (connected to the ink inlet 230 in fig. 1 and 2), through the ink inlet channel 121, through the filter 146 and the restrictor 145. The filter 146 and the flow restrictor 145 are proximate the second end 116 of the pressure chamber 110, with the second end 116 being the opposite end from the first end 115. The ink tank 120 supplies ink to the plurality of pressure chambers 110. In other examples described below, ink enters the ink inlet channel 121 directly from the edge of the substrate 100. The filter 146 may include a post similar to the post 141 shown in fig. 1. The flow restrictor 145 provides a flow resistance (as with the filter 146), and when a drop of ink is ejected from the pressure chamber 110, the flow restrictor 145 helps to restrict the flow of ink to the ink inlet 121, thereby directing more of the pressure created by the deformation of the piezoelectric plate to propel the drop.

Top view 4B shows the electrical wiring corresponding to drop ejector 150 shown in fig. 4A. The wire is part of an electrode layer 220 disposed on the outer second surface 212 of the piezoelectric plate 210 (fig. 3). The configuration of the wire width and spacing is to effectively drive the platen 210. In order to show spatial relationships, top view 5 shows a single drop ejector 150 (shown in phantom) disposed in substrate 100, below the corresponding wire disposed on piezoelectric plate 210. A signal line 251 is provided above each corresponding pressure chamber 110, and extends in a direction 52 perpendicular to the row direction 51. As shown in the example of fig. 5, the signal line 251 is disposed over the center of the corresponding pressure chamber 110. Each leading to a respective signal input pad 255. The orifice 132 is proximate the first end 115 of the pressure chamber 110, proximate the signal input pad 255. Referring to fig. 4A and 4B, the signal line 251 has a width B greater than 0.1 times the width W of the pressure chamber 110. The signal line width b is also greater than 0.2 times the thickness T of the piezoelectric plate 210 (fig. 3). Ground 261 is above and aligned with first side wall 161 and second side wall 162. The ground line is generally disposed on a center line between the respective pressure chambers 110, and extends in a direction 52 perpendicular to the row direction 51. The ground line 261 has a width c, which in many embodiments is greater than the width s of the sidewalls 161 and 162. The distance d between the signal line 251 and the adjacent ground line 261 is typically greater than 0.1W. The distance d between the signal line 251 and the adjacent ground line 261 is generally greater than 0.5T and less than 2T.

Top view 6 shows a portion of a piezoelectric inkjet printing device 10 according to an embodiment of the present invention. A pair of staggered rows 181 and 182 of drop ejectors 150 (similar to the drop ejector rows described above with reference to fig. 4A, 4B, and 5) are disposed on substrate 100 (fig. 3). Each of the liquid drop ejectors 150 is aligned along the row direction 51. The first and second rows 181, 182 are spaced apart from each other along a direction 52 perpendicular to the row direction 51. Each droplet ejector 150 in the first row 181 includes a pressure chamber 111 and each droplet ejector in the second row 182 includes a pressure chamber 112, which are disposed on the first side 101 of the substrate 100. In the example shown in fig. 6, ink is input to the ink feed channel 121 of each drop ejector 150 directly from the edge of the substrate 100 extending in the row direction 51. The pressure chambers 111 and 112 are delimited in the row direction 51 by a first side wall 161 and a second side wall 162. Each drop ejector also includes an orifice 132 in fluid communication with a respective pressure chamber 111 or 112. The orifices 132 are disposed in an orifice layer 330 on the second side 102 of the substrate 100. The electrode layer 220 disposed on the outer second surface 212 of the piezoelectric plate 210 (fig. 3) includes signal lines 251, with a corresponding signal line 251 for each droplet ejector 150 in each of the staggered rows 181 and 182 of droplet ejectors 150. Each signal line 251 leads to a respective signal input pad 255, the pads 255 of which are disposed between staggered rows 181 and 182 of droplet ejectors 150. The electrode layer 220 further includes at least one common ground line 264, and the common ground line 264 is connected to the ground line 261 above the first and second sidewalls 161 and 162 of each pressure chamber. The common ground line 264 extends in the row direction 51 and leads to the ground return pad 265. As illustrated in fig. 6, the common ground line 264 is disposed between the signal input pads 255 of the first staggered row 181 of drop ejectors 150 and the signal input pads 255 of the second staggered row 182 of drop ejectors 150. This signal input pad 255 and ground return pad 265 arrangement is advantageous for providing electrical interconnection from the piezoelectric inkjet printing device 10 to a printhead package (not shown) in a compact area.

The orifices 132 in row 181 are spaced at a pitch p, and the orifices 132 in row 182 are also spaced at a pitch p. The two rows are offset by a distance p/2 along the row direction 51. As a result, if a recording medium (not shown) is moved in direction 52 relative to piezoelectric inkjet printing device 10, with proper timing of droplet ejection by row 181 relative to the droplet ejectors in row 182, a composite line of printed dots at p/2 dot pitch can be printed on the recording medium. It is preferred that the piezoelectric inkjet printing device 10 have a relatively small print area, i.e., the distance between the orifices 132 in row 181 and the orifices 132 in row 182 along direction 52 is relatively short. To accomplish this, the drop injectors 150 in rows 181 and 182 are oriented in opposite directions such that the orifices 132 of the first staggered row 181 are proximate to the orifices 132 of the second row 182, and such that the pressure chambers 111 of the first row 181 and the pressure chambers 112 of the second row 182 extend in opposite directions in direction 52 from their respective orifices 132. In the embodiment shown in fig. 8, the printing area of the piezoelectric inkjet printing device 11 can be further reduced.

To provide a more reliable, short-circuit-free electrical interconnection, an electrically insulating masking layer 280 may be disposed over electrode layer 220, as shown in top view fig. 7, masking layer 280 including a window 281 over signal input pad 255 and a window 282 over ground return pad 265 to expose the pads for the electrical interconnection.

Fig. 8 shows a top view of a portion of a piezoelectric inkjet printing device 10 according to another embodiment of the present invention. The configuration shown in fig. 8 is similar to that shown in fig. 6, except for the location of the common ground line 264 and the return ground pad 265. In the embodiment shown in fig. 8, the first common ground line 264 is disposed proximate the second ends 116 of the respective pressure chambers 110 in the first row 181, and the second common ground line 266 is disposed proximate the second ends 116 of the respective pressure chambers 110 in the second row 182. The signal input pads 255 are disposed proximate the first ends 115 of the pressure chambers 110 in the rows 181 and 182, as in the embodiment shown in fig. 6. The first common ground line 264 leads to the first return ground pad 265, and the second common ground line 266 leads to the second return ground pad 267. The same electrically insulating masking layer 280 as shown in fig. 7 may be used to expose the pads for the electrical interconnect connections. In other embodiments (not shown), the return ground pads 265 and 267 can extend further toward the center such that they merge into a single return ground pad.

The droplet ejector 150 and wire distribution described above with reference to fig. 3, 4A, 4B, 5,6 and 8 is well suited for locally deflectably deforming the piezoelectric plate 210, causing local deflection of the piezoelectric plate 210 into one or more pressure chambers 110 when a voltage pulse is applied to an electrode corresponding to the pressure chamber 110, thereby ejecting ink droplets. For such applications, the piezoelectric plate 210 is polarized in a direction perpendicular to the first surface 211. In order to effectively deflect a piezoelectric plate 210 having a thickness T into a pressure chamber 110 having a width W, T is advantageously less than 0.5W, and in some embodiments, T may be less than 0.3W.

In an exemplary embodiment, the pitch p of each row is 0.01 inches, such that the orifices 132 in each row are disposed at 100 orifices per inch, and the two rows of drop ejectors can print a composite row of dots of 200 dots per inch. For a pitch p of 0.01 inch 254 microns, the pressure chamber width W may be 224 microns and the sidewall width s may be 30 microns, whereby s is less than 0.2p as described above with reference to fig. 4A. The thickness of the piezoelectric plate 210 itself is about 50 microns, which is advantageous in that it is less fragile. In the case of such an example,

as can be seen from fig. 4A and 4B, the nozzle pitch p is equal to the width B of the signal line 251 plus the width c of the ground line 261 plus twice the distance d between the signal line 251 and the ground line 261, i.e., p ═ B + c +2 d. In one example, the width b of the signal line 251 is 90 microns, the width c of the ground line 261 is 90 microns, and the distance d is 37 microns. At W-224 microns and d-37In the example of micrometers, the distance d between the signal line 251 and the adjacent ground line 261 is greater than 0.1W. In addition, in this example, the width b of the signal line 251 is greater than 0.1W. Further, for the piezoelectric plate 210 having a thickness T of 50 micrometers, the distance d between the signal line 251 and the adjacent ground line 261 is 37 micrometers, which is greater than 0.5T and less than 2T, and the width b of the signal line 251 is greater than 0.2T.

In the above embodiment, there is only a single pair of staggered rows 181 and 182 of drop ejectors 150. In other embodiments (not shown), there may be more pairs of staggered rows of drop ejectors to provide higher print resolution or increased ink coverage, or different types of ink (e.g., different colors of ink) may be ejected with each pair of staggered rows, or a range of different sizes of ink drops may be ejected with each pair of staggered rows.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims (10)

1. A piezoelectric inkjet printing device, comprising:

a substrate, comprising:

a first side; and

a second face opposite the first face; and

at least one pair of staggered rows of drop ejectors, each row aligned in a row direction, is disposed on the substrate, each drop ejector comprising:

a pressure chamber disposed on the first surface of the substrate and having a width W in the row direction, the pressure chamber being delimited by a first side wall and a second side wall; and

a nozzle orifice in fluid communication with the pressure chamber, the nozzle orifice being disposed in a nozzle orifice layer on the second side of the substrate;

a piezoelectric plate having a thickness T between a first surface abutting the pressure chamber and an outer second surface opposite the first surface;

an electrode layer disposed on the second surface of the piezoelectric plate, wherein the electrode layer comprises:

a signal line corresponding to each drop ejector in the at least one pair of staggered rows, each signal line leading to a respective signal input pad located between the staggered rows of drop ejectors in the at least one pair of staggered rows; and

and the at least one common ground wire is connected with the ground wire, the ground wire is arranged above the first side wall and the second side wall of each pressure chamber and aligned with the side walls, and the at least one common ground wire extends along the row direction and is communicated with the at least one ground return bonding pad.

2. The piezoelectric inkjet printing device of claim 1 wherein at least one common ground line is disposed between the signal input pads of a first staggered row and the signal input pads of a second staggered row of at least one pair of staggered rows.

3. The piezoelectric inkjet printing device of claim 1 wherein at least one pair of staggered rows of signal input pads are disposed proximate a first end of its respective pressure chamber and at least one common ground line is disposed proximate a second end of its respective pressure chamber, the second end being the end opposite the first end.

4. The piezoelectric inkjet printing device of claim 1 wherein a first row of the at least one pair of staggered rows and a second row of the at least one pair of staggered rows are spaced from each other along a first direction perpendicular to the row direction.

5. A piezoelectric inkjet printing apparatus according to claim 1, wherein the piezoelectric plate is polarized in a direction perpendicular to the first surface of the piezoelectric plate.

6. The piezoelectric inkjet printing device of claim 1, wherein the orifices of the first staggered row are adjacent to the orifices of the second staggered row, wherein the pressure chambers of the first staggered row and the pressure chambers of the second staggered row extend in opposite directions from the respective orifices.

7. The piezoelectric inkjet printing device according to claim 1, wherein each signal line is provided on a corresponding pressure chamber and extends in a direction perpendicular to the direction of the row.

8. The piezoelectric inkjet printing device of claim 7, wherein each signal line is disposed over a center of a respective pressure chamber.

9. The piezoelectric inkjet printing device according to claim 1, wherein the ground line is provided at an intermediate position between the respective pressure chambers and extends in a direction perpendicular to the direction of the row.

10. The piezoelectric inkjet printing device of claim 1 further comprising a masking layer disposed on the electrode layer, wherein the masking layer includes windows on the signal input pad and on the at least one ground return pad.

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