JP2021084390A - Liquid ejecting head and apparatus for ejecting liquid - Google Patents

Abstract

To reduce ejection variation between nozzle rows in a liquid ejecting head of a multi-nozzle row in which a plurality of nozzle rows are disposed.SOLUTION: A liquid ejection head 200a comprises: a plurality of nozzles 4 that eject liquid droplets; a plurality of individual liquid chambers 21 communicating with the plurality of nozzles; and a plurality of common liquid chambers 21 that supply the liquid to the individual liquid chambers 22; wherein the plurality of common liquid chambers 22 has: a plurality of central common liquid chambers (common liquid chambers 22 of a central row 210) in which other common liquid chambers are disposed on both sides thereof; and two end common liquid chambers (common liquid chambers 22 of an end row 220) disposed at one end and on one side of which another row is disposed; and wherein a cross-section of each central common liquid chamber as viewed from a direction in which the plurality of individual liquid chambers are arranged differs from a cross-section of each end common liquid chamber.SELECTED DRAWING: Figure 5

Description

The present invention relates to a liquid discharge head and a device for discharging a liquid.

In the liquid discharge head, a technique is already known in which a plurality of nozzle rows in which a plurality of nozzles are arranged are provided to form a multi-nozzle row, and nozzles are formed at a high density. Further, it is known that in the liquid discharge head of the multi-nozzle row, the discharge variation differs between the nozzle row arranged at the end and the nozzle row arranged at the center, and the quality of print recording deteriorates. ..

For example, Patent Documents 1 to 3 disclose techniques for providing a liquid discharge head with less fluctuation in discharge characteristics due to resonance of the liquid discharge head.
However, in the liquid discharge head of the multi-nozzle row, the discharge speed fluctuates between the nozzle rows due to the difference in the natural frequency of the head between the nozzle rows. Therefore, the techniques of Patent Documents 1 to 3 cannot sufficiently eliminate the discharge variation between the nozzle rows in the liquid discharge head of the multi-nozzle row.

An object of the present invention is to reduce discharge variation between nozzle rows in a liquid discharge head having a multi-nozzle row in which a plurality of nozzle rows are arranged.

In order to solve the above-mentioned problems, the liquid discharge head of the present invention is used.
A plurality of nozzles for ejecting droplets, a plurality of individual liquid chambers communicating with the plurality of nozzles, and a common liquid chamber for supplying liquid to the plurality of individual liquid chambers are provided, and the plurality of common liquid chambers are provided. It has a plurality of central common liquid chambers in which other common liquid chambers are arranged on both sides, and two end common liquid chambers provided at the ends and another row is arranged on one side. The cross-sectional area of the central common liquid chamber when viewed from the arrangement direction of the individual liquid chambers is different from the cross-sectional area of the end common liquid chambers.

According to the present invention, in a liquid discharge head having a multi-nozzle row in which a plurality of nozzle rows are arranged, it is possible to reduce discharge variations between the nozzle rows.

It is sectional drawing which follows the direction (the longitudinal direction of a pressure chamber) orthogonal to the nozzle arrangement direction of the liquid discharge head which concerns on one Embodiment of this invention. It is sectional drawing which follows the nozzle array direction of the liquid discharge head of FIG. It is sectional drawing along the nozzle arrangement direction explaining an example of the liquid discharge head of the multi-nozzle row which concerns on one Embodiment of this invention. It is a figure explaining the nozzle arrangement example of a multi-nozzle row. It is sectional drawing explaining an example of the liquid discharge head of Embodiment 1. FIG. It is sectional drawing explaining another example of the liquid discharge head of Embodiment 1. FIG. It is sectional drawing explaining an example of the liquid discharge head of Embodiment 2. FIG. It is sectional drawing explaining another example of the liquid discharge head of Embodiment 2. FIG. It is sectional drawing explaining an example of the liquid discharge head of Embodiment 3. FIG. It is an external perspective explanatory view which shows another example of the liquid discharge head which concerns on one Embodiment of this invention. It is sectional drawing which follows the direction orthogonal to the nozzle arrangement direction of the liquid discharge head of FIG. It is the schematic explanatory drawing of an example of the apparatus which discharges a liquid. It is a plane explanatory view of an example of the head unit of the apparatus which discharges a liquid. It is a block explanatory drawing of an example of a liquid circulation device. It is a plane explanatory view of the main part of the printing apparatus as the apparatus which discharges the liquid which concerns on this invention. It is explanatory drawing of the main part of the printing apparatus. It is a plane explanatory view of the main part of another example of the liquid discharge unit which concerns on this invention. It is a front explanatory view of still another example of the liquid discharge unit which concerns on this invention.

Hereinafter, the liquid discharge head and the device for discharging the liquid according to the embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments shown below, and can be modified within the range conceivable by those skilled in the art, such as other embodiments, additions, modifications, and deletions. However, as long as the action and effect of the present invention are exhibited, it is included in the scope of the present invention.

An example of the liquid discharge head according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional explanatory view along a direction orthogonal to the nozzle arrangement direction (longitudinal direction of the pressure chamber) of the head, and FIG. 2 is a cross-sectional explanatory view also along the nozzle arrangement direction. Here, only one row of piezoelectric elements is shown.

In the liquid discharge head 100 of the present embodiment, the nozzle plate 1, the flow path plate 2 which is an individual flow path member, and the diaphragm member 3 as a wall surface member are laminated and joined. A piezoelectric actuator 11 that displaces the vibration region (vibration plate) 30 of the diaphragm member 3 and a common flow path member 20 that also serves as a frame member of the head are provided.

The nozzle plate 1 has a plurality of nozzles 4 for discharging a liquid. The nozzle arrangement direction is a direction along a plurality of nozzles 4 arranged on the nozzle plate 1.

The flow path plate 2 includes a plurality of pressure chambers 6 communicating with the plurality of nozzles 4, an individual supply flow path 7 which is an individual flow path communicating with each pressure chamber 6, and one or more (one in the present embodiment). An intermediate supply flow path 8 is formed as a liquid introduction portion leading to the individual supply flow path 7.
FIG. 1 is a cross-sectional view of a part of the individual liquid chamber and the common liquid chamber of one embodiment.

The diaphragm member 3 has a plurality of displaceable diaphragms (vibration regions) 30 that form the wall surface of the pressure chamber 6 of the flow path plate 2. Here, the diaphragm member 3 has a two-layer structure (not limited), and is composed of a first layer 3A forming a thin wall portion from the flow path plate 2 side and a second layer 3B forming a thick wall portion.

Then, a deformable vibration region 30 is formed in a portion corresponding to the pressure chamber 6 in the first layer 3A which is a thin-walled portion. In the vibration region 30, a convex portion 30a, which is a thick portion to be joined to the piezoelectric actuator 11 in the second layer 3B, is formed.

Then, on the side of the diaphragm member 3 opposite to the pressure chamber 6, a piezoelectric actuator 11 including an electromechanical conversion element as a driving means (actuator means, pressure generating means) for deforming the vibration region 30 of the diaphragm member 3 is arranged. doing.

In the piezoelectric actuator 11, the piezoelectric member joined on the base member 13 is grooved by half-cut dicing, and a required number of columnar piezoelectric elements 12 are formed in a comb-teeth shape at predetermined intervals in the nozzle arrangement direction. ing. Then, the piezoelectric element 12 is joined to a convex portion 30a which is a thick portion formed in the vibration region 30 of the diaphragm member 3.

The piezoelectric element 12 is formed by alternately stacking piezoelectric layers and internal electrodes. The internal electrodes are pulled out to their end faces and connected to external electrodes (end face electrodes), and the flexible wiring member 15 is connected to the external electrodes. ing.

The common flow path member 20 forms a common supply flow path 10 leading to a plurality of pressure chambers 6. The common supply flow path 10 communicates with the intermediate supply flow path 8 serving as the liquid introduction portion through the opening 9 provided in the diaphragm member 3, and leads to the individual supply flow path 7 via the intermediate supply flow path 8. There is.

In the liquid discharge head 100, for example, by lowering the voltage applied to the piezoelectric element 12 from the reference potential (intermediate potential), the piezoelectric element 12 contracts, the vibration region 30 of the vibrating plate member 3 is pulled, and the volume of the pressure chamber 6 is reduced. As the pressure chamber 6 expands, the liquid flows into the pressure chamber 6.

After that, the voltage applied to the piezoelectric element 12 is increased to extend the piezoelectric element 12 in the stacking direction, and the vibration region 30 of the vibrating plate member 3 is deformed in the direction toward the nozzle 4 to contract the volume of the pressure chamber 6. , The liquid in the pressure chamber 6 is pressurized, and the liquid is discharged from the nozzle 4.

Next, an example of a liquid discharge head of a multi-nozzle row in which a plurality of nozzle rows are arranged will be described with reference to FIG. FIG. 3 is a cross-sectional explanatory view along the nozzle arrangement direction of the liquid discharge head of the multi-nozzle row. In FIG. 3, a part of the configuration example of FIG. 1 is omitted, and the same components as those of FIG. 1 are designated by the same reference numerals.
The liquid discharge head 200 of the multi-nozzle row includes a plurality of nozzles 4 for discharging droplets, a plurality of individual liquid chambers 21 communicating with the plurality of nozzles, and a common liquid chamber 22 for supplying liquid to the plurality of individual liquid chambers. , It is assumed that a plurality of columns having at least are arranged. In the following description, a plurality of nozzles 4 having one row will be referred to as a “nozzle row”, and a plurality of individual liquid chambers 21 having one row will be referred to as “individual liquid chamber rows”. Further, the liquid discharge head 200 is provided with a piezoelectric actuator 11 corresponding to each of a plurality of rows of nozzles.

The individual liquid chamber 21 corresponds to, for example, the functions of the pressure chamber 6, the individual supply flow path 7, and the intermediate supply flow path 8 shown in FIGS. 1 and 2.
The common liquid chamber 22 corresponds to, for example, the functions of the common supply flow path 10 shown in FIGS. 1 and 2, the opening 9, and the intermediate supply flow path 8.

The liquid discharge head 200 of FIG. 3 has six central rows 210 and two end rows 220. The central row 210 is a row in which other rows are arranged on both sides. The end row 220 is a row provided at the end of the liquid discharge head 200, and the other row is arranged on only one side.
The liquid discharge head 200 of the multi-nozzle row shown in FIG. 3 is an example, and does not limit the number of the plurality of rows. The liquid discharge head of the multi-nozzle row may have two or more central rows 210 and two end rows.

The common liquid chamber 22 in the central row 210 is adjacent to the common liquid chamber 22 in another row across a partition wall. On the other hand, the common liquid chamber 22 in the end row 220 is not adjacent to the common liquid chamber 22 in the other row.
Further, in the individual liquid chamber row of the central portion row 210, a partition end portion forming a common liquid chamber is present between the two individual liquid chamber rows. The individual liquid chamber rows of the end row 220 do not have a common liquid chamber sandwiched between the two individual liquid chamber rows.

The partition wall of the common liquid chamber 22 is a wall that partitions the common liquid chamber 22. The rigidity of the partition wall of the common liquid chamber 22 affects the natural frequency.
In the following description, as the partition wall of the common liquid chamber 22, the central partition wall 211 of the central row 210 and the end partition wall 221 of the end row 220, which are shown in FIG. 3, will be described. The central partition wall 211 corresponds to the above-mentioned partition wall end.
The central partition wall 211 constitutes a partition wall on the side surface of the common liquid chamber 22 provided in the central row 210, and serves as a partition wall between the adjacent common liquid chambers 22.
The end partition wall 221 is a common liquid chamber 22 provided in the end row 220, and is a partition wall provided at the ends of a plurality of rows (ends of the liquid discharge head 200).

Further, the partition walls of the central partition wall 211 and the end partition wall 221 are not limited to the portions constituting the side walls of the common liquid chamber 22. The partition walls of the central partition wall 211 and the end partition wall 221 may be from the nozzle plate 1 to the upper surface of the common liquid chamber 22 (the surface far from the nozzle plate 1), and may be from the nozzle plate 1 to an arbitrary position above the upper surface.
The height of the partition wall shall be a length along the direction in which the nozzle plate 1, the flow path plate 2, and the diaphragm member 3 are laminated.

FIG. 3 shows a cross section in which the liquid discharge head shown in FIG. 1 is arranged so that the nozzles are at the same position along a direction orthogonal to the nozzle arrangement direction, but the present invention is not limited to this. The nozzles may be arranged at different positions along the direction orthogonal to the nozzle arrangement direction. Specific examples will be described later with reference to FIG.

As described above, the central row 210 and the end row 220 have different natural frequencies depending on the presence or absence of arrangement of other rows and the like. For example, the difference in rigidity between the central partition wall 211 and the end partition wall 221 causes a difference in the natural frequency. Therefore, in the liquid discharge head of the multi-nozzle row, there arises a problem that the natural frequency differs depending on the nozzle row. This point will be described in detail.

In the head structure of the liquid discharge head, in order to form the nozzle at high density, it is necessary to arrange the machining of the pressure chamber and the piezoelectric element at high density, so that high precision workability is required, but the machining is performed. It's extremely difficult. In order to solve such a problem, a method is already known in which individual liquid chamber rows corresponding to nozzles are composed of two rows and the two rows are arranged in a staggered manner (for example, Patent Document 4).

In this method, two rows of pressure chambers, restrictors, and common liquid chambers are formed around the two rows of individual liquid chamber rows.
The individual liquid chamber rows in one row and the individual liquid chamber rows in the other row are arranged alternately.
If the nozzle pitch of the individual liquid chamber rows including the two rows is set to Pn, the individual liquid chamber pitch Pc becomes Pc = 2 × Pn, and the density pitch of one nozzle row realizes twice the density. There is. Similarly, if the individual liquid chamber rows are 4, 8, and 16, the nozzle pitch Pn can be 1/4, 1/8, and 1/16 with respect to the individual liquid chamber pitches of one row, and the density is increased. It is possible.

In the liquid discharge head that forms a high-density nozzle row with the conventional multi-nozzle row, the discharge variation differs between the end row and the center row among the plurality of nozzle rows, and the accuracy of the landing position is lowered. There is a problem that the quality of print records deteriorates.

First, the discharge principle of the liquid discharge head will be described with reference to FIGS. 1 and 2. In the liquid discharge head, when an electric signal is selectively input to a pressure generating element such as a piezoelectric element, the diaphragm member 3 or the like is deformed to change the volume of the pressure chamber 6, and the pressure is applied in the selected pressure chamber 6. appear. The generated pressure wave plays a role of discharging the liquid from the nozzle 4, and at the same time, propagates in the backward direction from the pressure chamber 6 and the individual supply flow path 7 toward the common supply flow path 10. The propagating pressure wave is reflected by the common supply flow path 10 and propagates back to the nozzle 4 later than the forward component. It is already known that the meniscus is disturbed by the influence of the pressure wave, and the required liquid speed and discharge amount cannot be discharged. The effect of the retreating pressure wave is due to the pressure wave returned to the common supply flow path 10. Since it differs depending on the number of channels driven at the same time and the drive frequency, the discharge speed and the discharge amount vary depending on the printing conditions.

In particular, when the drive frequency is increased, the remaining pressure wave is discharged before it is attenuated, so that the discharge speed and the discharge amount of the rear drop greatly fluctuate. Further, when the drive frequency matches the natural vibration of the structure of the head and resonates, the fluctuation of the ejection speed and the fluctuation of the ejection amount become large, which causes deterioration of the quality of the print record.
Due to such a mechanism, in a head configuration in which the density is increased by a plurality of nozzle rows, the ejection characteristics are different because the natural frequency of the structure is different between the nozzle row in the central row and the nozzle row at the end, and the print recording quality is improved. It leads to a decline.

Next, the problem of the liquid discharge head of the multi-nozzle row will be described with reference to FIG. In the liquid discharge head of the multi-nozzle row, the central row 210 has a configuration in which the partition wall constituting the common liquid chamber 22 is sandwiched between the two common liquid chambers 22. On the other hand, in the end row 220, the partition wall is not sandwiched between the common liquid chambers. Therefore, the natural frequency of the liquid chamber leading to the nozzle row of the central row 210 and the natural vibration of the liquid chamber leading to the nozzle row of the end row 220 are inevitably different. As described above, when the natural frequency of the structure differs depending on the row, the speed fluctuation generated according to the drive frequency differs between the end row 220 and the center row 210.
For example, in the configuration of the eight-row multi-nozzle row shown in FIG. 4, a speed deviation due to the nozzle row of the end row occurs. In the configuration example of FIG. 4, the nozzles in the 1st row and the 8th row surrounded by the broken line are the end row, and the nozzles in the 2nd to 7th rows are the central row. Since the nozzles in the end row serve as channels (ch) where speed fluctuations occur, a speed fluctuation difference occurs in the 2/8 row. When the nozzle arrangement pitch is used, a speed fluctuation difference occurs for each 7ch nozzle pitch. The 8-row nozzle row configuration shown in FIG. 4 is an example, and is not limited to this.

When the above-mentioned periodic speed fluctuation difference occurs, the appearance of the stimulus differs depending on the spatial frequency characteristic (VTF: Visual Transfer Function) of image vision, and the problem of periodic unevenness due to the characteristic occurs. It is desirable to reduce the uneven discharge speed fluctuation due to the influence of the natural frequency caused by the difference in the structure.

Therefore, the liquid discharge head of one embodiment is characterized in that the natural frequencies of the plurality of rows are matched in reducing the discharge variation between the nozzle rows of the head structure.

As a first feature, the liquid discharge head has a natural vibration between the end row and the center row according to the size of the partition wall forming the common liquid chamber (natural frequency as a direct principle). The size of the space in the common liquid chamber is relatively different so that the numbers match. In the liquid discharge head, for example, the common liquid chamber in the row having high rigidity of the partition wall of the common liquid chamber is made larger than the row having low rigidity. Further, in the liquid discharge head, for example, between the central row and the end row of the multi-nozzle row, the cross-sectional area of the common liquid chamber in the central row (common liquid chamber in the central row) is common to the end row. It shall be different from the cross-sectional area of the liquid chamber (liquid chamber common to the end row). Here, the cross-sectional area of the common liquid chamber is the area of the cross section when the common liquid chamber is viewed from the arrangement direction of a plurality of individual liquid chambers. The arrangement direction of the plurality of individual liquid chambers is the depth direction in FIG.

As a second feature, a groove is formed between the central rows so that the size of the partition wall of the common liquid chamber is the same, and the natural frequency of the central row is matched with the natural frequency of the end row. In the liquid discharge head, for example, the common liquid chamber in one row in the central row is adjacent to the common liquid chamber in one other row, and the common liquid chamber in one row is common to the other adjacent rows. It has a recess from the nozzle plate to at least the height of the common liquid chamber between it and the liquid chamber.
In this way, by matching the natural frequencies of the nozzle row structure including the common liquid chamber in all the nozzle rows, it is possible to reduce the discharge variation between the nozzle rows, so that the liquid discharge head with good print record quality. And an image forming apparatus can be provided.
The features of the present invention described above will be described in detail with reference to the drawings.

Embodiment 1.
5 and 6 are views for explaining a cross section of the liquid discharge head according to the first embodiment along the nozzle row arrangement direction. In the first embodiment, the case where the rigidity of the partition wall of the common liquid chamber 22 of the central row 210 is larger than the rigidity of the common liquid chamber 22 of the end row 220 will be described. In the liquid discharge head of the present embodiment, the common liquid chamber 22 in the central row 210 is made larger than the common liquid chamber 22 in the end row 220.

FIG. 5 shows an example of the liquid discharge head 200a in which the height of the common liquid chamber 22 in the central row 210 is made larger than the height of the common liquid chamber 22 in the end row 220.
When the partition wall of the common liquid chamber 22 of the central row 210 is larger than the partition wall of the common liquid chamber 22 of the end row 220 and the natural frequency (rigidity) is high, the natural frequency of the central row 210 is lowered. In addition, the height of the common liquid chamber 22 of the central row 210 is made larger than the height of the common liquid chamber 22 of the end row 220 to reduce the overall natural frequency. In FIG. 5, the height of the common liquid chamber 22 in the central row 210 surrounded by the alternate long and short dash line is increased.
This makes the natural frequencies of the rows match. In this way, it is possible to reduce the discharge variation between the nozzle rows and reduce the width of the head size.

FIG. 6 shows an example of the liquid discharge head 200b in which the width of the common liquid chamber in the central row 210 is made larger than the width of the common liquid chamber in the end row 220.
When the partition wall of the common liquid chamber 22 of the central row 210 is larger than the partition wall of the common liquid chamber 22 of the end row 220 and the natural frequency (rigidity) is high, the natural frequency of the central row 210 is lowered. In addition, the width of the common liquid chamber 22 of the central row 210 is made larger than the width of the common liquid chamber 22 of the end row 220 to reduce the overall natural frequency. In FIG. 6, the width of the common liquid chamber 22 in the central row 210 surrounded by the alternate long and short dash line is increased.
This makes the natural frequencies of the rows match. By doing so, it is possible to reduce the discharge variation between the nozzle rows and reduce the height of the head size.

Embodiment 2.
7 and 8 are views for explaining a cross section of the liquid discharge head according to the second embodiment along the nozzle row arrangement direction. In the second embodiment, the case where the rigidity of the partition wall of the common liquid chamber 22 of the end row 220 is larger than the rigidity of the common liquid chamber 22 of the central row 210 will be described. In the liquid discharge head of the present embodiment, the common liquid chamber 22 in the end row 220 is made larger than the common liquid chamber 22 in the central row 210.

FIG. 7 shows an example of the liquid discharge head 200c in which the height of the common liquid chamber 22 in the end row 220 is made larger than the height of the common liquid chamber 22 in the central row 210.
When the partition wall of the common liquid chamber 22 of the end row 220 is larger than the partition wall of the common liquid chamber 22 of the central row 210 and the natural frequency (rigidity) is high, the natural frequency of the end row 220 is lowered. In addition, the height of the common liquid chamber 22 of the end row 220 is made larger than the height of the common liquid chamber 22 of the central row 210 to reduce the overall natural frequency. In FIG. 7, the height of the common liquid chamber 22 of the end row 220 surrounded by the alternate long and short dash line 220 is increased.
This makes the natural frequencies between the rows the same. In this way, it is possible to reduce the discharge variation between the nozzle rows and reduce the width of the head size. In addition, miniaturization can be easily realized as compared with the configuration example of FIG.

FIG. 8 shows an example of the liquid discharge head 200d in which the width of the common liquid chamber in the central row 210 is larger than the width of the common liquid chamber in the end row 220.
When the partition wall of the common liquid chamber 22 of the end row 220 is larger than the partition wall of the common liquid chamber 22 of the central row 210 and the natural frequency (rigidity) is high, the natural frequency of the end row 220 is lowered. In addition, the width of the common liquid chamber 22 of the end row 220 is made larger than the width of the common liquid chamber 22 of the central row 210 to reduce the overall natural frequency. In FIG. 8, the width of the common liquid chamber 22 of the end row 220 surrounded by the alternate long and short dash line is increased.
This makes the natural frequencies between the rows the same. By doing so, it is possible to reduce the discharge variation between the nozzle rows and reduce the height of the head size.

Embodiment 3.
FIG. 9 is a diagram illustrating a cross section of the liquid discharge head of the third embodiment along the nozzle row arrangement direction. A groove is provided between the common liquid chambers of the central row 210 to form an independent common liquid chamber structure.
In the third embodiment, when the width between the common liquid chambers 22 in the central row 210 (the partition wall having the width between the adjacent common liquid chambers 22) is larger than the partition wall of the common liquid chamber 22 in the end row 220, the common liquid is used. A groove up to the height of the common liquid chamber 22 is provided between the chambers 22.

As shown in FIG. 9, in the central row 210 of the plurality of rows, the common liquid chamber in one row is adjacent to the common liquid chamber 22 in the other rows with a partition wall. On the other hand, in the end row 220, the common liquid chamber 22 is provided at the end and is not adjacent to the common liquid chamber 22 in another row. In such a case, the partition wall of the common liquid chamber 22 in the two adjacent rows of the central row 210 may be larger than the partition wall of the common liquid chamber 22 in the end row 220. Therefore, the liquid discharge head 200e is placed between the common liquid chamber 22 in the central row 210 and the common liquid chamber 22 in other adjacent rows up to the height of the common liquid chamber (from the nozzle plate 1 to the common liquid chamber 22). It is formed so as to have a recess 212 (up to the height).

The individual liquid chambers 21 and the common liquid chambers 22 in each row have an independent structure, and the common liquid chambers 22 in the central row 210 and the end row 220 have the same dimensional relationship. As a result, the natural frequencies are matched. By doing so, it is possible to reduce the discharge variation between the nozzle rows and to make the size of the common liquid chamber 22 the same, so that the fluid resistance in the common liquid chamber 22 can be made the same. As a result, it is possible to obtain a liquid discharge head with little variation in liquid supply performance.

Embodiment 4.
In each of the above embodiments, it is preferable that the liquid discharge head is not driven by a drive frequency that is a multiple of N (N is a positive integer) of the natural frequency. In this way, since resonance does not occur at the natural frequency of the structure, it is possible to reduce the nozzle row discharge variation that occurs due to the structural difference between the rows.

Other embodiments.
Another example of the liquid discharge head according to the embodiment of the present invention will be described with reference to FIGS. 10 and 11. FIG. 10 is an explanatory view of an external perspective of the head, and FIG. 11 is a cross-sectional explanatory view taken along a direction orthogonal to the nozzle arrangement direction of the head. Here, only one row of piezoelectric elements is shown.

The liquid discharge head 300 shown in FIGS. 10 and 11 is a circulation type liquid discharge head, in which a nozzle plate 1, a flow path plate 2, and a diaphragm member 3 as a wall surface member are laminated and joined. A piezoelectric actuator 11 that displaces the vibration region (vibration plate) 30 of the diaphragm member 3, a common flow path member 20 that also serves as a frame member of the head, and a cover 29 are provided.

The nozzle plate 1 has a plurality of nozzles 4 for discharging a liquid.

The flow path plate 2 includes a plurality of pressure chambers 6 that communicate with the plurality of nozzles 4 via the nozzle communication passages 5, and individual supply flow paths 7 and 2 that also serve as a plurality of fluid resistance portions that communicate with the plurality of pressure chambers 6. An intermediate supply flow path 8 or the like serving as one or a plurality of liquid introduction portions leading to the individual supply flow path 7 is formed.

Similar to FIGS. 1 and 2, the individual supply flow paths 7 have two first flow path portions 7A and a second flow path portion 7B having a higher fluid resistance than the pressure chamber 6, and the first flow path portion 7B. A third flow path portion 7C, which is arranged between the flow path portion 7A and the second flow path portion 7B and has a lower fluid resistance than the first flow path portion 7A and the second flow path portion 7B, is included.

The flow path plate 2 is configured by laminating a plurality of plate-shaped members 2A to 2E, but is not limited to this.

Further, the flow path plates 2 are formed into a plurality of individual recovery flow paths 57 and two or more individual recovery flow paths 57 along the surface direction of the flow path plates 2 that communicate with the plurality of pressure chambers 6 via the nozzle communication passages 5. An intermediate recovery flow path 58 is formed as one or a plurality of liquid outlets that communicate with each other.

The individual recovery flow path 57 includes a third flow path portion 57C having a lower fluid resistance than the first flow path portion 57A and the second flow path portion 57B. In the individual recovery flow path 57, the flow path portion 57D, which is downstream of the second flow path portion 57B in the circulation direction, has the same flow path width as the third flow path portion 57C.

The common flow path member 20 forms a common supply flow path 10 and a common recovery flow path 50. In the present embodiment, the common supply flow path 10 is composed of a flow path portion 10A that is aligned with the common recovery flow path 50 in the nozzle arrangement direction and a flow path portion 10B that is not lined up with the common recovery flow path 50. ..

The common supply flow path 10 communicates with the intermediate supply flow path 8 serving as the liquid introduction portion through the opening 9 provided in the diaphragm member 3, and leads to the individual supply flow path 7 via the intermediate supply flow path 8. There is. The common recovery flow path 50 communicates with the intermediate recovery flow path 58 serving as a liquid lead-out portion through the opening 59 provided in the diaphragm member 3, and leads to the individual recovery flow path 57 via the intermediate recovery flow path 58. There is.

Further, the common supply flow path 10 leads to the supply port 71, and the common recovery flow path 50 leads to the recovery port 72.

The other layer structure of the diaphragm member 3, the structure of the piezoelectric actuator 11, and the like are the same as those of the liquid discharge head 100 of FIGS. 1 and 2.

In the liquid discharge head 300 as well, in the same manner as the liquid discharge head 100 described above, the piezoelectric element 12 is extended in the stacking direction, and the vibration region 30 of the vibrating plate member 3 is deformed in the direction toward the nozzle 4 to form the pressure chamber 6 By contracting the volume of the pressure chamber 6, the liquid in the pressure chamber 6 is pressurized, and the liquid is discharged from the nozzle 4.

Further, the liquid that is not discharged from the nozzle 4 passes through the nozzle 4 and is collected from the individual collection flow path 57 to the common recovery flow path 50, and is again supplied from the common recovery flow path 50 to the common supply flow path 10 through the external circulation path. Nozzle. Further, even when the liquid is not discharged from the nozzle 4, the liquid circulates from the common supply flow path 10 through the pressure chamber 6 to the common recovery flow path 50, and is supplied again to the common supply flow path 10 through the external circulation path. To.

Even in the liquid discharge head 300, it is possible to attenuate the pressure fluctuation accompanying the liquid discharge and suppress the propagation to the common supply flow path 10 and the common recovery flow path 50 with a simple configuration.

Next, an example of the device for discharging the liquid according to the present invention will be described with reference to FIGS. 12 and 13. FIG. 12 is a schematic explanatory view of the device, and FIG. 13 is a plan explanatory view of an example of the head unit of the device.

The printing device 500, which is a device for discharging this liquid, guides and conveys the carry-in means 501 for carrying in the continuous body 510 and the continuous body 510 such as the continuous book paper and the sheet material carried in from the carry-in means 501 to the printing means 505. Guidance transport means 503, printing means 505 that discharges liquid to the continuum 510 to form an image, drying means 507 that dries the continuum 510, carry-out means 509 that carries out the continuum 510, and the like. It has.

The continuum 510 is sent out from the original winding roller 511 of the carrying-in means 501, guided and conveyed by the rollers of the carrying-in means 501, the guiding and conveying means 503, the drying means 507, and the carrying-out means 509, and is guided and conveyed by the winding roller 591 of the carrying-out means 509. It is wound up at.

The continuum 510 is conveyed on the transfer guide member 559 by the printing means 505 facing the head unit 550 and the head unit 555, an image is formed by the liquid discharged from the head unit 550, and the continuous body 510 is discharged from the head unit 555. Post-treatment is performed with the treatment liquid to be treated.

Here, the head unit 550 is provided with, for example, full-line head arrays 551A, 551B, 551C, and 551D for four colors from the upstream side in the transport direction (hereinafter, referred to as "head array 551" when the colors are not distinguished). Is placed.

Each head array 551 is a liquid discharging means, and discharges black K, cyan C, magenta M, and yellow Y liquids to the conveyed continuum 510, respectively. The types and numbers of colors are not limited to this.

The head array 551 is, for example, in which the liquid discharge heads (which are also simply referred to as “heads”) 100 according to the present invention are arranged in a staggered pattern on the base member 552, but the head array 551 is not limited to this. As the head 100 arranged in the head array 551, the liquid discharge heads 200a to 200e described above can be used. The same applies to the head 100 described below.

Next, an example of the liquid circulation device will be described with reference to FIG. FIG. 14 is a block explanatory view of the circulation device. Although only one head is shown here, when a plurality of heads are arranged, the supply side liquid path and the recovery side liquid path are provided on the supply side and the recovery side of the plurality of heads via a manifold or the like, respectively. Will connect.

The liquid circulation device 600 includes a supply tank 601, a recovery tank 602, a main tank 603, a first liquid feed pump 604, a second liquid feed pump 605, a compressor 611, a regulator 612, a vacuum pump 621, a regulator 622, and a supply side pressure sensor 631. , The recovery side pressure sensor 632 and the like.

Here, the compressor 611 and the vacuum pump 621 constitute means for generating a differential pressure between the pressure in the supply tank 601 and the pressure in the recovery tank 602.

The supply-side pressure sensor 631 is connected to the supply-side liquid path between the supply tank 601 and the head 100 and connected to the supply port 71 of the head 100. The recovery side pressure sensor 632 is connected between the head 100 and the recovery tank 602 to a recovery side liquid path connected to the recovery port 72 of the head 100.

One of the recovery tanks 602 is connected to the supply tank 601 via the first liquid feed pump 604, and the other of the recovery tank 602 is connected to the main tank 603 via the second liquid feed pump 605.

As a result, the liquid flows from the supply tank 601 through the supply port 71 into the head 100, is collected from the collection port 72 to the collection tank 602, and the liquid is collected from the collection tank 602 to the supply tank 601 by the first liquid feeding pump 604. By being sent, a circulation path through which the liquid circulates is constructed.

Here, a compressor 611 is connected to the supply tank 601 and is controlled so that a predetermined positive pressure is detected by the supply side pressure sensor 631. On the other hand, a vacuum pump 621 is connected to the recovery tank 602, and the recovery side pressure sensor 632 controls so that a predetermined negative pressure is detected.

As a result, the negative pressure of the meniscus can be kept constant while circulating the liquid through the head 100.

Further, when the liquid is discharged from the nozzle 4 of the head 100, the amount of liquid in the supply tank 601 and the recovery tank 602 decreases. Therefore, the liquid is replenished from the main tank 603 to the recovery tank 602 by using the second liquid feeding pump 605 as appropriate.

The timing of replenishing the liquid from the main tank 603 to the recovery tank 602 is provided in the recovery tank 602, such as replenishing the liquid when the liquid level height of the liquid in the recovery tank 602 falls below a predetermined height. It can be controlled by the detection result of the liquid level sensor or the like.

Next, another example of the printing device as a device for discharging the liquid according to the present invention will be described with reference to FIGS. 15 and 16. FIG. 15 is a plan view of the main part of the device, and FIG. 16 is a side view of the main part of the device.

The printing device 400 is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged over the left and right side plates 491A and 491B to movably hold the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407.

The carriage 403 is equipped with a liquid discharge unit 440 in which the liquid discharge head 100 and the head tank 441 according to the present invention are integrated. The liquid discharge head 100 of the liquid discharge unit 440 discharges liquids of, for example, yellow (Y), cyan (C), magenta (M), and black (K). Further, the liquid discharge head 100 is mounted by arranging a nozzle array composed of a plurality of nozzles in the sub-scanning direction orthogonal to the main scanning direction and directing the discharge direction downward.

The liquid discharge head 100 is connected to the liquid circulation device 600 described above, and a liquid of a required color is circulated and supplied.

The printing device 400 includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

The transport belt 412 attracts the paper 410 and transports it at a position facing the liquid discharge head 100. The transport belt 412 is an endless belt, and is hung between the transport roller 413 and the tension roller 414. Adsorption can be performed by electrostatic adsorption, air suction, or the like.

Then, the transport belt 412 orbits in the sub-scanning direction by rotationally driving the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 for maintaining / recovering the liquid discharge head 100 is arranged on the side of the transport belt 412.

The maintenance / recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the liquid discharge head 100, a wiper member 422 that wipes the nozzle surface, and the like.

The main scanning movement mechanism 493, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.

In the printing apparatus 400 configured in this way, the paper 410 is fed onto the transport belt 412 and sucked, and the paper 410 is conveyed in the sub-scanning direction by the orbital movement of the transport belt 412.

Therefore, by driving the liquid discharge head 100 in response to the image signal while moving the carriage 403 in the main scanning direction, the liquid is discharged to the stopped paper 410 to form an image.

Next, another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 17 is an explanatory plan view of a main part of the unit.

Among the members constituting the liquid discharge unit 440 and the device for discharging the liquid, a housing portion composed of side plates 491A, 491B and a back plate 491C, a main scanning moving mechanism 493, a carriage 403, and a liquid. It is composed of a discharge head 100.

It is also possible to form a liquid discharge unit in which the above-mentioned maintenance / recovery mechanism 420 is further attached to, for example, the side plate 491B of the liquid discharge unit 440.

Next, still another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 18 is a front explanatory view of the unit.

The liquid discharge unit 440 is composed of a liquid discharge head 100 to which the flow path component 444 is attached and a tube 456 connected to the flow path component 444.

The flow path component 444 is arranged inside the cover 442. A head tank 441 may be included instead of the flow path component 444. Further, a connector 443 that electrically connects to the liquid discharge head 100 is provided above the flow path component 444.

In the present application, the liquid to be discharged may have a viscosity and surface tension that can be discharged from the head, and is not particularly limited, but the viscosity becomes 30 mPa · s or less at room temperature, under normal pressure, or by heating or cooling. It is preferable that it is a thing. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functionalizing materials such as surfactants, biocompatible materials such as DNA, amino acids and proteins, and calcium. , Solvents, suspensions, emulsions, etc. containing edible materials such as natural pigments, etc., for example, inks for inkjets, surface treatment liquids, constituents of electronic elements and light emitting elements, and formation of electronic circuit resist patterns. It can be used for applications such as liquids for three-dimensional modeling.

Piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heat-generating resistors, and electrostatic actuators that consist of a vibrating plate and counter electrodes are used as energy sources for discharging liquid. Includes what to do.

The "liquid discharge unit" is a liquid discharge head integrated with functional parts and a mechanism, and includes an aggregate of parts related to liquid discharge. For example, the "liquid discharge unit" includes a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, a main scanning movement mechanism, a liquid circulation device in which at least one of the configurations is combined with a liquid discharge head, and the like.

Here, "integration" means, for example, a liquid discharge head and a functional component, a mechanism in which the mechanism is fixed to each other by fastening, adhesion, engagement, etc., or one in which one is movably held with respect to the other. Including. Further, the liquid discharge head, the functional parts, and the mechanism may be detachably attached to each other.

For example, as a liquid discharge unit, there is one in which a liquid discharge head and a head tank are integrated. In addition, there are some that are connected to each other by a tube or the like to integrate the liquid discharge head and the head tank. Here, a unit including a filter can be added between the head tank of these liquid discharge units and the liquid discharge head.

Further, as a liquid discharge unit, there is a liquid discharge head and a carriage integrated.

Further, as a liquid discharge unit, there is a liquid discharge head in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably by a guide member forming a part of the scanning movement mechanism. In some cases, the liquid discharge head, the carriage, and the main scanning movement mechanism are integrated.

Further, as a liquid discharge unit, there is a carriage to which a liquid discharge head is attached, in which a cap member which is a part of the maintenance / recovery mechanism is fixed, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. ..

Further, as a liquid discharge unit, there is a liquid discharge unit in which a tube is connected to a head tank or a liquid discharge head to which a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. Through this tube, the liquid of the liquid storage source is supplied to the liquid discharge head.

The main scanning movement mechanism shall also include a single guide member. Further, the supply mechanism includes a single tube and a single loading unit.

The "device for discharging a liquid" includes a device provided with a liquid discharge head or a liquid discharge unit and driving the liquid discharge head to discharge the liquid. The device for discharging the liquid includes not only a device capable of discharging the liquid to a device to which the liquid can adhere, but also a device for discharging the liquid into the air or the liquid.

The "device for discharging the liquid" may include means for feeding, transporting, and discharging paper to which the liquid can be attached, as well as a pretreatment device, a posttreatment device, and the like.

For example, as a "device that ejects a liquid", an image forming apparatus that ejects ink to form an image on paper, and a three-dimensional object (three-dimensional object) are formed in layers in order to form a three-dimensional object. There is a three-dimensional modeling device (three-dimensional modeling device) that discharges the modeling liquid into the powder layer.

Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included.

The above-mentioned "material to which a liquid can adhere" means a material to which a liquid can adhere at least temporarily, such as one that adheres and adheres, and one that adheres and permeates. Specific examples include paper, recording paper, recording paper, film, recording media such as cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, and media such as inspection cells. Yes, including anything to which the liquid adheres, unless otherwise specified.

The material of the above-mentioned "material to which liquid can be attached" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics or the like as long as the liquid can be attached even temporarily.

Further, the "device for discharging the liquid" includes, but is not limited to, a device in which the liquid discharge head and the device to which the liquid can adhere move relatively. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

In addition, as a "device for ejecting a liquid", a treatment liquid coating device for ejecting a treatment liquid to a paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, etc. There is an injection granulation device that granulates fine particles of the raw material by injecting a composition liquid in which the raw material is dispersed in a solution through a nozzle.

In addition, image formation, recording, printing, printing, printing, modeling, etc. in the terms of the present application are all synonymous.

1 Nozzle plate 2 Flow plate 3 Diaphragm member 4 Nozzle 11 Piezoelectric actuator 20 Common flow path member 20
21 Individual liquid chambers 22 Common liquid chambers 100, 200, 200a to 200e, 300 Liquid discharge head 210 Central row 211 Central bulkhead 212 Recess 220 End row 221 End bulkhead

JP-A-2015-85523 Japanese Patent No. 6193747 Japanese Patent No. 6169948

Claims (9)

Multiple nozzles that eject droplets and
A plurality of individual liquid chambers leading to the plurality of nozzles and
A plurality of common liquid chambers for supplying liquid to the plurality of individual liquid chambers are provided.
The plurality of common liquid chambers are a plurality of central common liquid chambers in which other common liquid chambers are arranged on both sides, and two end common liquid chambers provided at an end and another row is arranged on one side. And have
A liquid discharge head characterized in that the cross-sectional area of the central portion common liquid chamber when viewed from the arrangement direction of the plurality of individual liquid chambers is different from the cross-sectional area of the end common liquid chamber. The liquid discharge head according to claim 1, wherein the common liquid chamber having a high rigidity of a partition wall of the common liquid chamber has a larger cross-sectional area than the common liquid chamber having a low rigidity. The rigidity of the central common liquid chamber is higher than that of the end common liquid chamber.
The liquid discharge head according to claim 2, wherein the height of the common liquid chamber of the central common liquid chamber is larger than that of the end common liquid chamber. The rigidity of the central common liquid chamber is higher than that of the end common liquid chamber.
The liquid discharge head according to claim 2, wherein the width of the common liquid chamber of the central common liquid chamber is larger than that of the end common liquid chamber. The rigidity of the end common liquid chamber is higher than that of the central common liquid chamber.
The liquid discharge head according to claim 2, wherein the height of the common liquid chamber of the end common liquid chamber is larger than that of the central common liquid chamber. The rigidity of the end common liquid chamber is higher than that of the central common liquid chamber.
The liquid discharge head according to claim 2, wherein the width of the common liquid chamber of the end common liquid chamber is larger than that of the central common liquid chamber. Multiple nozzles that eject droplets and
A plurality of individual liquid chambers leading to the plurality of nozzles and
A plurality of common liquid chambers for supplying liquid to the plurality of individual liquid chambers are provided.
The plurality of common liquid chambers include a central common liquid chamber in which other common liquid chambers are arranged on both sides and an end common liquid chamber provided at the end and another common liquid chamber is arranged on one side. Have
One of the common liquid chambers in the central portion is adjacent to one of the other common liquid chambers.
It is characterized by having a recess from the nozzle plate on which the plurality of nozzles are formed to at least the height of the common liquid chamber between the one common liquid chamber and the adjacent other common liquid chamber. Liquid discharge head. The liquid discharge head according to any one of claims 1 to 7, wherein the drive frequency of the liquid discharge head is not driven by an N (N is a positive integer) multiple of the natural frequency. A device for discharging a liquid, comprising the liquid discharge head according to any one of claims 1 to 8.

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