JP5531481B2 - Liquid discharge head - Google Patents

Description

  The present invention relates to a structure of a liquid discharge head.

  As an image forming apparatus, an ink jet printer that forms an image by ejecting ink droplets from a liquid ejection head onto a recording medium such as paper is widely used. Among them, a so-called on-demand method that selectively ejects only ink droplets for recording is currently mainstream.

A conventional on-demand type liquid discharge head has a structure as shown in FIG.
Referring to FIG. 1, a droplet discharge port 1 for discharging a droplet, a liquid chamber 2 for supplying a liquid to the droplet discharge port 1, a restrictor 6, a pressure generating means 5 for generating pressure, and a flexible member 4 are provided. A plurality of liquid droplet ejection means 8 are provided, and a common liquid chamber 3 for supplying a liquid to each of the plurality of liquid chambers 2 through respective connection flow paths 7 is formed. In the restrictor 6, the pressure in the liquid chamber 2 is transmitted to the droplet discharge port 1 when the pressure generating means 5 increases the pressure in the liquid chamber 2 and discharges droplets through the droplet discharge port 1. It is a resistor to make it.

  However, since the restrictor 6 has a fixed shape, the pressure transmitted from the liquid chamber 2 is not sufficiently absorbed by the common liquid chamber 3, and pressure interference is caused from the common liquid chamber 3 to the adjacent droplet discharge means 8. This causes a phenomenon (crosstalk) in which droplets are discharged from the adjacent droplet discharge ports 1 and adversely affects the discharge stability.

  On the other hand, in order to realize recording with high image quality, a liquid discharge head having high density and high discharge efficiency is required. On the other hand, a plurality of comb-like electrodes electrically separated on the lower surface of the diaphragm constituting the wall surface of the discharge chamber with which the droplet discharge nozzle communicates, and an electromechanical transducer formed between the two electrodes. There has been proposed a liquid discharge head in which a laminated piezoelectric structure including a plurality of piezoelectric bodies is provided, and a diaphragm is deformed by applying a voltage to the laminated piezoelectric structure to expand and contract (see Patent Document 1). ).

  In recent years, due to demands for higher density and smaller size, the influence of pressure interference between liquid ejecting means has deteriorated in liquid ejecting heads. According to the technique of Patent Document 1, it is possible to efficiently deform the diaphragm in a high-density liquid discharge head, but as a result of causing pressure interference in the adjacent droplet discharge means, the discharge stability No technology has been proposed to solve the problem of adversely affecting the system.

  An object of the present invention has been made in view of the above-described problems in the prior art, and in a liquid discharge head having a plurality of droplet discharge means, other droplets generated when one droplet discharge means discharges droplets. It is an object of the present invention to provide a liquid discharge head capable of suppressing the influence of pressure transmission to the discharge means.

In order to solve the above problems, a liquid discharge head according to the present invention is as follows.
[1] At least a droplet discharge port, a liquid chamber having one end communicating with the droplet discharge port and the other end communicating with a common liquid chamber, and a pressure generating means for generating pressure for pressurizing the liquid in the liquid chamber In a liquid discharge head comprising a droplet discharge means and the common liquid chamber,
The liquid chamber is partitioned into a first liquid chamber that communicates with the droplet discharge port and a second liquid chamber that communicates with the common liquid chamber, and a first liquid chamber that connects the first liquid chamber and the second liquid chamber. 1 connection flow path, and a second connection flow path for connecting the second liquid chamber and the common liquid chamber,
The second liquid chamber has an inclined surface whose cross-sectional area gradually increases or decreases on at least one surface, and an expansion ratio of the cross-sectional area expanding from the second connection channel toward the second liquid chamber is The shape is smaller than the expansion ratio of the cross-sectional area expanding from the first connection channel toward the second liquid chamber ,
At least one surface constituting the first liquid chamber is made of a flexible member, and the flexible member is provided with pressure generating means, and the pressure generating means deforms and displaces the flexible member of the first liquid chamber. Displacement generating means for causing
At least one surface constituting the second liquid chamber is made of a flexible member, and the flexible member is provided with pressure generating means, and the pressure generating means deforms and displaces the flexible member of the second liquid chamber. Displacement generating means for causing
In the liquid discharge head, a displacement direction of the first liquid chamber by the displacement generation unit and a displacement generation direction of the second liquid chamber by the displacement generation unit are opposite to each other .
[2] The first liquid chamber has, on at least one surface, an inclined surface whose cross-sectional area gradually decreases toward the end of the first connection flow path, from the maximum cross-sectional area of the first liquid chamber. The liquid discharge head according to [1], wherein the liquid discharge head has a shape that continuously reduces to the minimum cross-sectional area of the end portion of the first connection flow path.
[3] The second liquid chamber has an inclined surface whose cross-sectional area gradually decreases toward the end of the second connection flow path, and the second connection flow from the maximum cross-sectional area of the second liquid chamber. The liquid discharge head according to any one of [1] to [2], wherein the liquid discharge head has a shape that continuously reduces to a minimum cross-sectional area of a road end.
[ 4 ] The flexible member of the second liquid chamber and the flexible member of the first liquid chamber are continuous and integral members, and the displacement generating means of the second liquid chamber and the first liquid chamber The liquid discharge head according to any one of [1] to [3] , wherein the displacement generating means are separate members.
[ 5 ] The displacement generating means includes a first electrode and a second electrode to which the same or different voltages are applied, and a piezoelectric layer in which at least one piezoelectric layer is laminated between the first electrode and the second electrode. The liquid discharge head according to any one of [1] to [4] , wherein the liquid discharge head is an element.
[ 6 ] The first electrode in the displacement generating means of the first liquid chamber is connected to the second electrode in the displacement generating means of the second liquid chamber, and the first electrode in the displacement generating means of the first liquid chamber. 2 electrodes, a liquid discharge head according to the above [5], wherein it is connected to the first electrode in the displacement generating means of the second liquid chamber.
[ 7 ] Between the second liquid chamber and the common liquid chamber, at least one or more liquid chambers substantially the same as the second liquid chamber are provided in communication with each other via the second connection channel. The liquid discharge head according to any one of [1] to [6] , wherein

  According to the present invention, in a liquid discharge head having a plurality of droplet discharge means, a liquid discharge head capable of suppressing the influence of pressure transmission to other droplet discharge means that occurs when one droplet discharge means discharges droplets. Can be provided.

  According to the liquid discharge head of the present invention, it is possible to suppress the occurrence of pressure interference (crosstalk) between the flow paths through the common liquid chamber, and it becomes possible to stably discharge the liquid droplets, thereby obtaining good print quality.

It is sectional drawing which shows an example of the conventional liquid discharge head. FIG. 3 is an exploded perspective view of the first embodiment of the liquid ejection head of the present invention. It is sectional drawing which shows the AA 'cross section in the exploded perspective view of FIG. 2, and a BB' cross section, (a) is a standby state, (b) is the state which the displacement by a displacement generation means produced ( c) shows a state where the displacement generating means returns to the standby state. It is a disassembled perspective view in the 2nd embodiment of the liquid discharge head of this invention. 5A and 5B are cross-sectional views showing an AA ′ cross section and a BB ′ cross section in the exploded perspective view of FIG. 4, in which FIG. Each state returns to the state. It is a disassembled perspective view in the 3rd embodiment of the liquid discharge head of this invention. 7A and 7B are cross-sectional views showing an AA ′ cross-section and a BB ′ cross-section in the exploded perspective view of FIG. 6, in which FIG. Each state returns to the state.

  Hereinafter, a liquid discharge head according to the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments of the examples shown below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art. Any aspect is included in the scope of the present invention as long as the operations and effects of the present invention are exhibited.

[Example 1]
FIG. 2 is an exploded perspective view of the first embodiment (inkjet head) which is an example of the liquid discharge head of the present invention.
As shown in FIG. 2, the liquid discharge head of the present invention has a liquid droplet discharge port 1 (in the figure, each liquid droplet discharge means is denoted by 1a, 1b and 1c, respectively), and the liquid. Common to at least one, preferably a plurality of liquid discharge means including at least a first liquid chamber 9 communicating with the droplet discharge port 1, a second liquid chamber 11 communicating with the common liquid chamber 3, and a pressure generating means described later. And a liquid chamber 3.
In addition, a first connection flow path 10 that connects the first liquid chamber 9 and the second liquid chamber 11, a second connection flow path 12 that connects the second liquid chamber 11 and the common liquid chamber 3, and The flexible member 4 constituting at least one surface of the liquid chamber 9 and the second liquid chamber, the displacement generating means 30 as the pressure generating means of the first liquid chamber provided in the flexible member 4, and the pressure generation of the second liquid chamber It comprises displacement generating means 31 as means.

  And the 2nd liquid chamber 11 has an inclined surface in which a cross-sectional area increases / decreases gradually in at least one surface, specifically, as shown in FIG. The shape has an inclined surface such that the cross-sectional area gradually decreases. Specifically, the cross-sectional area continuously decreases from the maximum cross-sectional area of the second liquid chamber 11 to the minimum cross-sectional area of the second connection flow path end 12. Shape.

In this embodiment, the first liquid chamber displacement generating means 30 is a piezoelectric element formed by laminating the first electrode 15, the piezoelectric layer 14, and the second electrode 16, and the second liquid chamber displacement generating means 30. Reference numeral 31 denotes a piezoelectric element in which the first electrode 17, the piezoelectric layer 13, and the second electrode 18 are laminated.
In this embodiment, the displacement generating means 30 for the first liquid chamber and the displacement generating means 31 for the second liquid chamber are continuous and integral members.

  FIG. 3 is a cross-sectional view taken along the lines AA ′ and BB ′ of FIG. 2. The first liquid chamber displacement generating means 30 and the second liquid chamber displacement generating means 31 are shown in FIG. From the standby state shown, the liquid is supplied from the common liquid chamber 3 to the second liquid chamber 11 and the first liquid chamber 9 by deformation as shown in (b), and as shown in (c). A state in which liquid flows from the first liquid chamber 9 to the second liquid chamber 11 and the common liquid chamber 3 when the displacement generating means 30 of the one liquid chamber and the displacement generating means 31 of the second liquid chamber return to the standby state will be described. Is.

FIG. 3A shows a cross-sectional view of the liquid ejection head in a standby state. The liquid ejection head includes a first liquid chamber 9, a second liquid chamber 11, a first connection channel 10, and a second connection. The flow path 12 is filled with a liquid and is in a standby state when discharging the liquid.
For example, when a voltage is applied to the mutation generating means, the displacement generating means 30 of the first liquid chamber is deformed as shown in FIG. 3B, whereby a deformation displacement occurs in the flexible member 4, and the first The pressure in the liquid chamber 9 decreases, and the liquid is supplied from the second liquid chamber 11 toward the first liquid chamber 9. On the other hand, in the second liquid chamber 11, the displacement generating means 31 of the second liquid chamber is deformed in the same direction as the deformation direction of the first liquid chamber, and the flexible member 4 is deformed and displaced. The pressure decreases, and a flow rate 21 for supplying liquid from the first liquid chamber 9 to the second liquid chamber 11 and a flow rate 22 for supplying liquid from the common liquid chamber 3 to the second liquid chamber 11 are generated.

  The second liquid chamber 11 has an inclined surface on the side surface so that the cross-sectional area gradually increases or decreases in the direction of the common liquid chamber 3, and has a cross-sectional area that expands from the second connection channel 12 toward the second liquid chamber 11. The enlargement ratio is smaller than the enlargement ratio of the cross-sectional area expanding from the first connection channel 10 toward the second liquid chamber 11. Therefore, it acts as a diffuser in the direction from the second connection flow path 12 to the second liquid chamber 11, and the pressure loss generated between the second connection flow path 12 and the second liquid chamber 11 is caused by the second liquid chamber 11. And the flow rate 22 supplied from the common liquid chamber 3 toward the second liquid chamber 11 is larger than the pressure loss generated between the first liquid chamber 9 and the second connection chamber 10. It becomes larger than the flow rate 21 supplied in the direction. Accordingly, the liquid is supplied from the common liquid chamber 3 to the first liquid chamber 9 through the second connection flow path 12, the second liquid chamber 11, and the first connection flow path 10.

Here, “the expansion ratio of the cross-sectional area expanding from the second connection flow path 12 toward the second liquid chamber 11 is smaller than the expansion ratio of the cross-sectional area expanding from the first connection flow path 10 toward the second liquid chamber 11. `` It is a shape ''
The expansion ratio of the cross-sectional area proportional to the distance in the flow direction, for example
(1) The expansion ratio S2 of the cross-sectional area that expands from the second connection flow path 12 toward the second liquid chamber 11 is the distance d from the second connection flow path end with respect to the cross-sectional area of the second connection flow path end. The ratio of the cross-sectional area of the second liquid chamber at the point,
(2) The expansion ratio S1 of the cross-sectional area that expands from the first connection flow path 10 toward the second liquid chamber 11 is the distance d from the first connection flow path end with respect to the cross-sectional area of the first connection flow path end. When it is the ratio of the cross-sectional area of the second liquid chamber at the point,
(3) satisfying the relationship of S2 ≦ S1.
Represents that.

  Since the liquid chamber has an inclined surface in which the cross-sectional area gradually expands (or gradually decreases), the expansion ratio of the cross-sectional area can also be evaluated by the gradient of the inclined surface. For example, in the region where the wall surface from the end of the connection flow path to the liquid chamber is inclined, the angle formed by the opposing wall surfaces is expressed in the second direction from the common liquid chamber 3 toward the first liquid chamber 9. As an enlargement ratio of the cross-sectional area of the liquid chamber 11, the angle α formed by the two inclined surfaces facing each other is preferably around 65 ° so that the pressure loss is maximized.

Next, as shown in FIG. 3C, when the displacement generating means 30 of the first liquid chamber and the displacement generating means 31 of the second liquid chamber return to the standby state, the pressure in the first liquid chamber 9 is changed. The liquid in the first liquid chamber 9 flows into the second liquid chamber at the same time as the liquid droplets are discharged from the liquid droplet discharge port 1.
On the other hand, in the second liquid chamber 11, when the displacement generating means 31 of the second liquid chamber 11 returns to the standby state, the pressure in the second liquid chamber 11 increases, and the second liquid chamber 11 changes to the first liquid chamber. 9 and the flow rate 22 supplied from the second liquid chamber 11 to the common liquid chamber 3 are generated.
The shape in which the cross-sectional area of the second liquid chamber 11 on the common liquid chamber side continuously decreases acts as a nozzle in the flow in the direction from the second liquid chamber 11 to the second connection flow path 12. The pressure loss generated between the chamber 9 and the first connection flow path 12 is larger than the pressure loss generated between the second liquid chamber 11 and the second connection flow path 12, The flow rate 21 supplied to the first liquid chamber 9 is larger than the flow rate 22 supplied from the second liquid chamber 11 to the common liquid chamber 3.
Accordingly, the flow rate 20 in the direction from the first liquid chamber 9 to the second liquid chamber 11 is reduced by the flow rate 21 from the second liquid chamber 11 to the first liquid chamber 9, and the common liquid chamber is transferred from the first liquid chamber 9. The pressure transmitted to 3 is also relieved.

  As described above, in this embodiment, the displacement generating means 30 of the first liquid chamber and the displacement generating means 31 of the second liquid chamber are continuous and integrated members. The displacement generating means 31 for the two liquid chambers can be simultaneously manufactured by the same manufacturing method.

[Example 2]
FIG. 4 is an exploded perspective view of a second embodiment (inkjet head) which is another example of the liquid ejection head of the present invention.
As shown in FIG. 4, the liquid discharge head of the present invention includes a droplet discharge port 1, a first liquid chamber 9, a second liquid chamber 11, a common liquid chamber 3, a first connection channel 10, and a second connection channel. 12, the flexible member 4, the displacement generating means 30 of the first liquid chamber, and the displacement generating means 31 of the second liquid chamber.

  Here, the displacement generating means 30 of the first liquid chamber constituted by the piezoelectric layer 14, the first electrode 15 and the second electrode 16, the second constituted by the piezoelectric layer 13, the first electrode 17 and the second electrode 18. The displacement generating means 31 of the liquid chamber is divided and is a separate member. For this reason, the displacement direction of the displacement generating means 30 in the first liquid chamber can be the same direction as the displacement direction of the displacement generating means 31 in the second liquid chamber, or can be in the opposite direction.

  Hereinafter, the case where the displacement direction of the displacement generating means 30 of the first liquid chamber and the displacement direction of the displacement generating means 31 of the second liquid chamber are opposite will be described with reference to FIG.

  5A and 5B are cross-sectional views showing the AA ′ cross section and the BB ′ cross section in the exploded perspective view of FIG. 4. FIG. 5A shows a state in which the displacement is generated by the displacement generating means, and FIG. Each of the generation means returns to the standby state, and the first liquid chamber 9 to the second liquid chamber 11 are deformed in the opposite directions by the displacement generation means 30 of the first liquid chamber and the displacement generation means 31 of the second liquid chamber being deformed in opposite directions. The state of the liquid flowing in the common liquid chamber 3, the displacement generating means 30 of the first liquid chamber, and the displacement generating means 31 of the second liquid chamber return from the common liquid chamber 3 to the second liquid chamber 11 and the second liquid chamber 11. FIG. 6 is a diagram illustrating a situation where a liquid is supplied to one liquid chamber.

FIG. 5A shows a state in which the pressure in the first liquid chamber 9 decreases due to the deformation of the first liquid chamber displacement generating means 30 and the liquid is supplied from the second liquid chamber 11 to the first liquid chamber 9. Is shown.
On the other hand, in the second liquid chamber 11, since the displacement generating means 31 of the second liquid chamber 11 is deformed in the opposite direction to the displacement generating means 30 of the first liquid chamber, the pressure in the second liquid chamber 11 increases, A flow rate 21 for supplying the liquid from the second liquid chamber 11 to the first liquid chamber 9 and a flow rate 22 for supplying the liquid from the second liquid chamber 11 to the common liquid chamber 3 are generated.

  However, as described in the first embodiment, since the shape of the second liquid chamber 11 acts as a nozzle, the flow rate 21 supplied to the first liquid chamber 9 is larger than the flow rate 22 supplied to the common liquid chamber 3. The liquid supply from the second liquid chamber 11 to the first liquid chamber 9 is promoted.

Next, as shown in FIG. 5B, when the displacement generating means 30 of the first liquid chamber and the displacement generating means 31 of the second liquid chamber return to the standby state, the pressure in the first liquid chamber 9 is changed. The liquid in the first liquid chamber 9 flows into the second liquid chamber 11 at the same time as the liquid droplets are discharged from the liquid droplet discharge port 1.
On the other hand, in the second liquid chamber 11, when the displacement generating means 31 of the second liquid chamber returns to the standby state, the pressure in the second liquid chamber 11 decreases, and the liquid is transferred from the second liquid chamber 11 to the first liquid chamber 9. And a flow rate 22 for supplying liquid from the second liquid chamber 11 to the common liquid chamber 3 are generated.
However, since the shape of the second liquid chamber 11 acts as a diffuser, the flow rate 22 from the common liquid chamber 3 to the second liquid chamber 11 is more than the flow rate 21 in the direction from the first liquid chamber 9 to the second liquid chamber 11. growing.
Accordingly, the flow rate 20 from the first liquid chamber 9 to the second liquid chamber 11 is reduced by the flow rate 22 from the common liquid chamber 3 to the second liquid chamber 11, and the first liquid chamber 9 to the common liquid chamber 3. The pressure transmitted to is also relieved.

  In the present embodiment, the pressure generating means of the first liquid chamber 9 has been described as a displacement generating means such as a piezoelectric element, but is not limited thereto, and can be appropriately selected from known pressure generating means. A means for generating bubbles by a heating resistor is also applicable.

Example 3
FIG. 6 is an exploded perspective view of a third embodiment (inkjet head) which is still another example of the liquid discharge head of the present invention.
As shown in FIG. 6, the liquid discharge head of the present invention includes a droplet discharge port 1, a first liquid chamber 9, a second liquid chamber 11, a common liquid chamber 3, a first connection flow path 10, and a second connection flow path. 12, the flexible member 4, the displacement generating means 30 of the first liquid chamber, and the displacement generating means 31 of the second liquid chamber.
Displacement generating means 30 of the first liquid chamber constituted by the piezoelectric layer 14, the first electrode 15 and the second electrode 16, and the second liquid chamber constituted by the piezoelectric layer 13, the first electrode 17 and the second electrode 18. The displacement generating means 31 is the same member.

  In the liquid discharge head of this embodiment, the second liquid chamber 11 has an inclined surface on the side surface so that the cross-sectional area gradually increases and decreases, and the cross-sectional area gradually decreases toward the end of the second connection channel 12. The first liquid chamber 9 has a shape that continuously reduces from the maximum cross-sectional area of the second liquid chamber 11 to the minimum cross-sectional area of the second connection flow path end portion 12, and the first liquid chamber 9 has the first connection flow path 10. Has an inclined surface whose cross-sectional area gradually decreases toward the end of the first liquid chamber 9, and continuously decreases from the maximum cross-sectional area of the first liquid chamber 9 to the minimum cross-sectional area of the end of the first connection channel 10. Shape.

  7A and 7B are cross-sectional views showing the AA ′ cross section and the BB ′ cross section in the exploded perspective view of FIG. 6. FIG. 7A shows a state where the displacement is generated by the displacement generating means, and FIG. Each of the generating means returns to a standby state, and the displacement means 30 of the first liquid chamber and the displacement means 31 of the second liquid chamber are deformed to deform the first liquid chamber 9 to the second liquid chamber 11 and the common liquid chamber 3. And the second liquid chamber 11 and the first liquid chamber 9 from the common liquid chamber 3 when the displacement generating means 30 of the first liquid chamber and the displacement generating means 31 of the second liquid chamber return to the standby state. The situation where the liquid is supplied is explained.

FIG. 7A shows the first connection flow path 10 from the second liquid chamber 11 to the first liquid chamber 9 because the pressure in the first liquid chamber 9 decreases due to the deformation of the displacement generating means 30 of the first liquid chamber. The state in which the liquid is supplied through is shown. At that time, since the first connection channel 10 acts as a diffuser, supply of the liquid from the second liquid chamber 11 to the first liquid chamber 9 is promoted.
On the other hand, in the second liquid chamber 11, since the displacement generating means 31 of the second liquid chamber is deformed in the same direction as the displacement generating means 30 of the first liquid chamber, the pressure in the second liquid chamber 11 decreases, and the first A flow rate 21 for supplying the liquid from the liquid chamber 9 toward the second liquid chamber and a flow rate 22 for supplying the liquid from the supply liquid chamber 3 toward the second liquid chamber are generated.
With respect to the flow rate 21 for supplying the liquid from the first liquid chamber 9 toward the second liquid chamber, the first connection channel 10 acts as a nozzle and supplies the liquid from the supply liquid chamber 3 toward the second liquid chamber. Since the second connection flow path 12 acts as a diffuser with respect to the flow rate 22, the pressure loss due to the second connection flow path 12 is larger than the pressure loss due to the first connection flow path 10, so The flow rate 22 in the liquid chamber direction is larger than the flow rate 21 in the direction from the first liquid chamber 9 to the second liquid chamber, and the liquid is supplied from the common liquid chamber 3 to the second liquid chamber 11.

Next, as shown in FIG. 7B, when the displacement generating means 30 of the first liquid chamber and the displacement generating means 31 of the second liquid chamber return to the standby state, the pressure in the first liquid chamber 9 is changed. At the same time as the liquid droplets are discharged from the liquid droplet discharge port 1, the liquid in the first liquid chamber 9 passes through the first connection channel 10 and flows into the second liquid chamber 11.
On the other hand, in the second liquid chamber 11, when the displacement generating means 31 of the second liquid chamber returns to the standby state, the pressure in the second liquid chamber 11 increases, and the second liquid chamber 11 moves from the second liquid chamber 11 toward the first liquid chamber. A flow rate 21 for supplying the liquid and a flow rate 22 for supplying the liquid from the second liquid chamber 11 toward the common liquid chamber are generated.
For the flow rate 21 for supplying the liquid from the second liquid chamber 11 toward the first liquid chamber, the first connection flow path is for the diffuser, and for the flow rate 22 for supplying the liquid from the second liquid chamber 11 toward the common liquid chamber, Since the second connection channel acts as a nozzle, the flow rate 21 from the second liquid chamber 11 toward the first liquid chamber 9 is larger than the flow rate 22 from the second liquid chamber 11 toward the common liquid chamber 3.
Accordingly, the flow rate 20 from the first liquid chamber 9 toward the second liquid chamber 11 is reduced by the flow rate 21 from the second liquid chamber toward the first liquid chamber 11. Further, the pressure transmitted to the common liquid chamber 3 is also relaxed.

  Note that the expansion ratio of the cross-sectional area is expressed in terms of the angle formed by the opposing wall surfaces in the region where the wall surface from the end of the connection flow path to the liquid chamber is inclined. Α (an angle formed by two opposing inclined surfaces), which is an enlargement ratio of the cross-sectional area of the second liquid chamber 11, and the cross-sectional area of the first liquid chamber 9 from the second liquid chamber 11 toward the first liquid chamber 9 It is preferable that β (an angle formed by two opposing inclined surfaces) that is an enlargement ratio is around 65 ° so that the pressure loss is maximized.

In the liquid discharge head of this embodiment, the first connection flow path 10 functions as a nozzle or a diffuser. For this reason, when supplying liquid from the common liquid chamber 3 to the first liquid chamber 9 as compared with the liquid discharge head in the first embodiment described above, the first connection flow path acts as a diffuser. The liquid is supplied more smoothly from the liquid chamber 11 to the first liquid chamber 9. Further, when the liquid is discharged from the first liquid chamber 9 to the common liquid chamber 3, since the first connection channel 10 acts as a nozzle, the liquid is discharged from the first liquid chamber 9 to the second liquid chamber 11. It can be further suppressed.
Therefore, the liquid discharge head of this embodiment can reduce the pressure transmission to the adjacent droplet discharge means more effectively than the liquid discharge head in the first embodiment shown in FIGS. The occurrence of crosstalk can be further suppressed.

  As another embodiment, for example, the first electrode 15 in the displacement generating means 30 of the first liquid chamber is connected to the second electrode 18 in the displacement generating means 31 of the second liquid chamber, and the first A mode in which the second electrode 16 in the displacement generating means 30 of the liquid chamber is connected to the first electrode 17 in the displacement generating means 31 of the second liquid chamber can be mentioned.

  As another embodiment, for example, at least one other liquid chamber that is substantially the same as the second liquid chamber is interposed between the second liquid chamber 11 and the common liquid chamber 3 via the second connection channel 12. An aspect in which one or more are provided is mentioned, and by adopting such an aspect, it is possible to reduce pressure interference between the flow paths through the common liquid chamber.

  As described above, according to the present invention, in a liquid discharge head having a plurality of droplet discharge means, the influence of pressure transmission to other droplet discharge means that occurs when one droplet discharge means is discharged is suppressed. An image forming apparatus equipped with the liquid discharge head can suppress the occurrence of pressure interference between the flow paths through the common liquid chamber, and can stably discharge liquid droplets. Therefore, good quality printing is possible.

DESCRIPTION OF SYMBOLS 1 Droplet discharge port 2 Liquid chamber 3 Common liquid chamber 4 Flexible member 5 Pressure generating means 6 Restrictor 7 Connection flow path 8 Droplet discharge means 9 1st liquid chamber 10 1st connection flow path 11 2nd liquid chamber 12 1st 2 connection flow path 13 piezoelectric layer 14 in second liquid chamber 14 piezoelectric layer 15 in first liquid chamber first electrode 16 in first liquid chamber second electrode 17 in first liquid chamber first electrode 18 in second liquid chamber second Second electrode 30 in liquid chamber Displacement generating means 31 in first liquid chamber Displacement generating means in second liquid chamber α Cross-sectional area enlargement ratio (angle of inclined surface)
β Cross-sectional area enlargement ratio (angle of inclined surface)

JP 2003-326707 A

Claims (7)

Droplet discharge comprising at least a droplet discharge port, a liquid chamber having one end communicating with the droplet discharge port and the other end communicating with a common liquid chamber, and pressure generating means for generating pressure to pressurize the liquid in the liquid chamber In a liquid discharge head comprising means and the common liquid chamber,
The liquid chamber is partitioned into a first liquid chamber that communicates with the droplet discharge port and a second liquid chamber that communicates with the common liquid chamber, and a first liquid chamber that connects the first liquid chamber and the second liquid chamber. 1 connection flow path, and a second connection flow path for connecting the second liquid chamber and the common liquid chamber,
The second liquid chamber has an inclined surface whose cross-sectional area gradually increases or decreases on at least one surface, and an expansion ratio of the cross-sectional area expanding from the second connection channel toward the second liquid chamber is The shape is smaller than the expansion ratio of the cross-sectional area expanding from the first connection channel toward the second liquid chamber ,
At least one surface constituting the first liquid chamber is made of a flexible member, and the flexible member is provided with pressure generating means, and the pressure generating means deforms and displaces the flexible member of the first liquid chamber. Displacement generating means for causing
At least one surface constituting the second liquid chamber is made of a flexible member, and the flexible member is provided with pressure generating means, and the pressure generating means deforms and displaces the flexible member of the second liquid chamber. Displacement generating means for causing
The liquid discharge head according to claim 1, wherein a displacement direction of the first liquid chamber by the displacement generation unit and a displacement generation direction of the second liquid chamber by the displacement generation unit are opposite to each other .   The first liquid chamber has, on at least one surface, an inclined surface whose cross-sectional area gradually decreases toward the end of the first connection flow path, and the first liquid chamber has a first cross-sectional area from the maximum cross-sectional area of the first liquid chamber. The liquid discharge head according to claim 1, wherein the liquid discharge head has a shape that continuously reduces to the minimum cross-sectional area of the end portion of the connection flow path.   The second liquid chamber has an inclined surface whose cross-sectional area gradually decreases toward the second connection flow path end, and the second connection flow path end from the maximum cross-sectional area of the second liquid chamber. The liquid discharge head according to claim 1, wherein the liquid discharge head has a shape that continuously reduces to the minimum cross-sectional area. The flexible member of the second liquid chamber and the flexible member of the first liquid chamber are continuous and integral members, and the displacement generating means of the second liquid chamber and the displacement of the first liquid chamber liquid discharge head according to any one of claims 1 to 3, characterized in that the generation means is a separate member separated respectively. The displacement generating means is a first electrode and a second electrode to which the same or different voltages are applied, and a piezoelectric element in which at least one piezoelectric layer is laminated between the first electrode and the second electrode. The liquid discharge head according to claim 1 , wherein the liquid discharge head is provided. The first electrode in the displacement generating means of the first liquid chamber is connected to the second electrode in the displacement generating means of the second liquid chamber, and the second electrode in the displacement generating means of the first liquid chamber is the liquid discharge head according to claim 5, characterized in that it is connected to the first electrode in the displacement generating means of the second liquid chamber. Between the second liquid chamber and the common liquid chamber, at least one liquid chamber that is substantially the same as the second liquid chamber is provided in communication with the second liquid passage through the second connection channel. The liquid discharge head according to claim 1 .

Images