Patent Description:
A liquid ejection device which ejects a liquid material (a liquid) such as ink to a desired position is known in the related art (for example, refer to <CIT>). In the liquid ejection device described in <CIT>, a piezoelectric element is provided in a part of a pipe provided in an ejection head. Such a liquid ejection device pushes out a liquid in the flow path while pressing the liquid and ejects the liquid by constricting and deforming a flow path using the piezoelectric element. <CIT> discloses methods and apparatuses for dispensing samples or reagents onto a target object.

In the liquid ejection device as described in <CIT>, ejecting various liquids in place of ink used at the time of two-dimensional printing in the related art is required. For example, a liquid to be ejected may be a dispersion liquid as well as a solution. Examples of a dispersoid contained in the dispersion liquid include organic materials such as resin materials, inorganic materials such as metal particles and oxide particles, and biological materials such as cells and genes.

Such various liquids have various viscosities and many liquids have a higher viscosity than the ink used in the two-dimensional printing in the related art. The liquid ejection device described in <CIT> deforms a flow path through the driving of the piezoelectric element and pushes out a liquid through the flow path.

However, if a liquid to be ejected has a high viscosity, even when pressure is applied from the piezoelectric element to the flow path, liquid droplets may be formed on an ejection port of the liquid ejection device while remaining attached to the ejection port and liquid droplets may not fly to an object to which a liquid is ejected in some cases. That is to say, since the liquid ejection device described in <CIT> is not appropriate for ejecting a highly viscous liquid, there has been a demand for a liquid ejection device capable of ejecting a highly viscous liquid.

The present invention is made in view of such circumstances, and an object of the present invention is to provide a liquid ejection unit capable of appropriately ejecting a highly viscous liquid. Furthermore, another object of the present invention is to provide a liquid ejection device having such a liquid ejection unit and capable of appropriately ejecting a highly viscous liquid.

In order to achieve the above objects, one aspect of the present invention provides a liquid ejection unit which includes: a liquid holding section which has an ejection port through which a liquid is ejected and which holds the liquid; a pressure adjustment section which is configured to adjust a pressure of a liquid held in the liquid holding section; and a displacement member which is configured to displace at least a part of the liquid whose pressure is adjusted and eject the liquid from the liquid holding section.

According to the present invention, it is possible to provide a liquid ejection unit capable of appropriately ejecting a highly viscous liquid. Furthermore, it is possible to provide a liquid ejection device having such a liquid ejection unit and capable of appropriately ejecting a highly viscous liquid.

A liquid ejection unit and a liquid ejection device according to a first embodiment of the present invention will be described below with reference to <FIG>. In all the following drawings, in order to make the drawings easy to see, the dimensions, the ratios, and the like of the constituent elements may be appropriately changed.

In the following description, an xyz rectangular coordinate system is utilized and positional relationships between respective members will be described with reference to this xyz rectangular coordinate system. Here, a predetermined direction in a horizontal plane is assumed to be an x axis direction, a direction in the horizontal plane orthogonal to the x axis direction is assumed to be a y axis direction, and a direction (that is, a vertical direction) orthogonal to the x axis direction and the y axis direction is a z axis direction.

Also, an upward direction in the vertical direction is assumed to be a +z direction and a downward direction in the vertical direction is assumed to be a -z direction. Similarly, the words "above", "upward" and "upper" are each assumed to mean the +z direction. The words "below", "downward" and "lower" are each assumed to mean the -z direction.

Furthermore, in the following description, the expression "when viewed in a plan view" is assumed to be viewing an object from above and a "plan shape" is assumed to be a shape when the object is viewed from above.

<FIG> is a schematic perspective view illustrating liquid ejection units <NUM> and a liquid ejection device <NUM>. As illustrated in <FIG>, the liquid ejection device <NUM> in this embodiment includes an ejection section <NUM> configured to hold a liquid and eject the held liquid, an attachment section <NUM> to which the ejected liquid droplets adhere, a placement section <NUM> on which the attachment section <NUM> is placed, and a control unit <NUM> configured to control an operation of each unit of the liquid ejection device <NUM>.

The liquid ejection device <NUM> ejects the liquid held in the ejection section <NUM> toward the attachment section <NUM>. The liquid ejected from the liquid ejection device <NUM> is not particularly limited and may be a dispersion liquid containing a dispersion medium in which particles are dispersed or a solution.

Examples of the particles dispersed in the dispersion medium include organic materials such as polymer particles and inorganic materials such as fine metal particles and inorganic oxide particles. Furthermore, cells can be used as the particles.

In this embodiment, a description will be provided assuming that the liquid ejected uing the liquid ejection device <NUM> is a dispersion liquid having cells dispersed in a dispersion medium. In this case, as the dispersion medium, well-known buffer solutions such as a phosphate buffered saline and a Hank's balanced salt solution can be used.

The ejection section <NUM> includes the plurality of (four in <FIG>) liquid ejection units <NUM> and a transport section <NUM> configured to transport each of the liquid ejection units <NUM>.

The plurality of liquid ejection units <NUM> may eject the same liquid L or may eject liquids L different from each other. In the following description, the liquid L ejected using the liquid ejection unit is a dispersion liquid having particles P dispersed therein.

The liquid ejection unit <NUM> includes a liquid ejection head <NUM> and a pressure adjustment section 120A connected to the liquid ejection head <NUM>.

The details of the liquid ejection unit <NUM> will be described later.

The transport section <NUM> includes a support member <NUM> and a linear movement section <NUM>.

The support member <NUM> is a rectangular member when viewed in a plan view and supports a plurality of liquid ejection heads <NUM>. The plurality of liquid ejection heads <NUM> are supported by the support member <NUM> and arranged along an x axis.

The linear movement section <NUM> is a long member which extends in the y axis direction. The linear movement section <NUM> moves the support member <NUM> horizontally in the y axis direction. Both ends of the linear movement section <NUM> are supported by the support member (not shown).

The linear movement section <NUM> can adopt, for example, a known linear actuator including a stepping motor as a drive source.

The transport section <NUM> moves the support member <NUM> in the y axis direction, thereby moving a plurality of ejection units <NUM> supported by the support member <NUM> in the y axis direction which is a double-headed arrow direction indicated by a reference symbol D1.

The attachment section <NUM> is arranged in an ejection direction of the liquid droplet L1 ejected from the ejection section <NUM> and has the liquid droplet L1 adhering thereto. Although the attachment section <NUM> may be of any type in accordance with a type of liquid L to be ejected, the purpose of ejection, and the like, in this embodiment, a Petri dish is used as the attachment section <NUM>.

Also, the attachment section <NUM> may be a so-called well plate in which a plurality of wells are arranged in a matrix form at equal intervals or may be a micro-electrode array (MEA) in which micro-electrodes are regularly arranged.

The placement section <NUM> includes an x stage <NUM>, a y stage <NUM>, and a base <NUM>.

The x stage <NUM> has the attachment section <NUM> placed thereon and supports and fixes the attachment section <NUM>. Furthermore, the x stage <NUM> moves the attachment section <NUM> horizontally in the x axis direction which is a double-headed arrow direction indicated by a reference symbol D2.

The y stage <NUM> moves the x stage <NUM> horizontally in the y axis direction which is a double-headed arrow direction indicated by a reference symbol D3. The base <NUM> supports the y stage <NUM>.

The placement section <NUM> can adopt a known constitution as an xy stage.

The transport section <NUM> and the placement section <NUM> control relative positions of the liquid ejection unit <NUM> and the attachment section <NUM>. Thus, in the liquid ejection device <NUM>, it is possible to adhere the liquid ejected from the liquid ejection unit <NUM> to a desired position on the attachment section <NUM>.

The control unit <NUM> performs control to create a signal for operating each unit of the liquid ejection device <NUM> and supply the signal to each unit.

The control unit <NUM> controls an operation of each unit to create, for example, a drive signal to be supplied to the ejection section <NUM> and a drive signal to be supplied to the placement section <NUM>, and supply the signals to each unit.

<FIG> is a schematic diagram illustrating the liquid ejection unit <NUM>.

The liquid ejection head <NUM> includes a liquid holding section <NUM>, a support section <NUM>, a displacement member <NUM>, and a pipe <NUM>. The pressure adjustment section 120A includes a supply section <NUM> and a detection unit <NUM>.

The liquid holding section <NUM> is a tubular member which extends substantially parallel to the z axis direction which is a liquid ejection direction. The liquid holding section <NUM> is formed of, for example, a material such as glass or a resin material. A wall surface of the liquid holding section <NUM> facing an inside 111x may be subjected to a liquid repellent treatment or a lyophilic treatment in accordance with the characteristics of a liquid L flowing thorugh the inside. As a result, the liquid ejection head enables to eject the liquid appropriately according to the purpose of the present invention. The liquid holding section <NUM> may be a tubular member or a plate-like member having a flow path formed therein.

It is desirable that the liquid holding section <NUM> have light transmissivity so that a state of the liquid L flowing through the inside can be checked.

The liquid holding section <NUM> has an inner diameter gradually decreasing in the -z direction. A lower end of the liquid holding section <NUM> is open as an ejection port 111a. For example, an outer diameter of the liquid holding section <NUM> is several mm. Furthermore, an inner diameter of the ejection port 111a is several tens of µm or more and several hundreds of µm or less. An upper end of the liquid holding section <NUM> is connected to the pipe <NUM>.

The liquid holding section <NUM> ejects the liquid L through the ejection port 111a in the -z direction.

The support section <NUM> supports the liquid holding section <NUM> in an attachable or detachable manner. The support section <NUM> can adopt various commonly known constitutions as long as they can support the liquid holding section <NUM>.

The support section <NUM> includes a support main body 112a which supports the liquid holding section <NUM> and a screw 112x which fixes the liquid holding section <NUM> to the support main body 112a.

In <FIG>, the support main body 112a is shown as a rectangular parallelepiped member having an insertion section 112b into which the liquid holding section <NUM> is inserted. The screw 112x fixes the liquid holding section <NUM> inserted into the insertion section 112b in a screw manner.

The displacement member <NUM> is a rectangular member when viewed in a plan view provided on an upper surface <NUM> of the support main body 112a. In <FIG>, a shape of the displacement member <NUM> when viewed in a plan view is shown as a square. For example, the shape of the displacement member <NUM> when viewed in a plan view is a square of several mm×several mm.

The displacement member <NUM> is provided at a position in which the displacement member <NUM> and the liquid holding section <NUM> overlap when viewed in a plan view. The shape of the displacement member <NUM> when viewed in a plan view is larger than a shape of the liquid holding section <NUM> when viewed in a plan view. The shape of the displacement member <NUM> when viewed in a plan view is a square. A length of one side of the square is longer than the outer diameter of the liquid holding section <NUM>.

The displacement member <NUM> has a lower surface 113a adhered to the upper surface <NUM> of the support main body 112a and an upper surface 113b adhered to a lower surface 131a of the support member <NUM>.

Although a piezoelectric element, an actuator constituted of a magnet and a coil, and the like can be used as the displacement member <NUM>, it is desirable that a piezoelectric element be used. The piezoelectric element can have, for example, a structure in which electrodes for applying a voltage are provided on an upper surface and a lower surface of a piezoelectric material. In this case, the displacement member <NUM> applies a compressive stress in a lateral direction of the upper and lower electrodes by applying a voltage between the upper and lower electrodes of the displacement member <NUM> (the piezoelectric element) from the control unit <NUM>. Thus, the displacement member <NUM> vibrates in an upward/downward direction of a film surface (a double-headed arrow direction indicated by a reference symbol D4 in the drawing).

The vibration direction of the displacement member <NUM> is the z axis direction and is set to be substantially parallel to the ejection direction of the liquid L. Here, the word "substantially" in the expression "substantially parallel" means that it is not required that the vibration direction of the displacement member <NUM> and the ejection direction of the liquid L be mathematically strictly parallel to the z axis. For example, the vibration direction of the displacement member <NUM> may be tilted within ±<NUM>° with respect to an z axis when the ejection direction of the liquid L (that is, the z axis direction) is <NUM>°.

By performing the operation as described above, the displacement member <NUM> displaces the support section <NUM> substantially parallel to the ejection direction of the liquid L and further displaces at least a part of the liquid L held by the liquid holding section <NUM> and the liquid holding section <NUM> supported by the support section <NUM>.

In this specification, "displacement" refers to changing a position of a subject. In addition, in this embodiment, "displacement" means that a subject changes coordinates in the xyz rectangular coordinate system. In this meaning, the displacement of the liquid holding section <NUM> refers to changing coordinates of the liquid holding section <NUM> in the xyz rectangular coordinate system. In this embodiment, the liquid holding section <NUM> is displaced in the z axis direction due to the vibration of the displacement member <NUM>.

The piezoelectric material is not particularly limited and may be appropriately selected in accordance with the purpose thereof. In addition, examples thereof include lead zirconate titanate (PZT), bismuth iron oxide, metal niobate, barium titanate, and materials obtained by adding a metal or a different oxide to these materials. Among these, lead zirconate titanate (PZT) is preferable.

The pipe <NUM> connects the liquid holding section <NUM> to the pressure adjustment section 120A. The pipe <NUM> includes a first pipe 115a, a second pipe 115b, a third pipe 115c, and a branch pipe 115d.

The first pipe 115a, the second pipe 115b, and the third pipe 115c are pipes formed of a soft resin material. Examples of the soft resin material include polyurethane, silicone rubber, fluororesin, and the like.

The branch pipe 115d is a three-way pipe (a three-way joint) and can adopt a commonly known constitution.

In the pipe <NUM>, one end of the first pipe 115a is connected to the upper end of the liquid holding section <NUM>. The other end of the first pipe 115a is connected to the branch pipe 115d.

The second pipe 115b and the third pipe 115c are connected to the branch pipe 115d. The second pipe 115b has one end connected to the branch pipe 115d and the other end connected to the supply section <NUM>. The third pipe 115c has one end connected to the branch pipe 115d and the other end connected to the detection unit <NUM>.

The supply section <NUM> is connected via the liquid holding section <NUM> and the pipe <NUM> and supplies the liquid L to the liquid holding section <NUM> in a closed system. The supply section <NUM> may be any section as long as it can supply a liquid, may be, for example, a section which supplies the liquid L using the force of gravity or the like, and may be a section which can supply a liquid at a desired rate using a microvolume-pump such as a syringe pump, a tube pump, or a diaphragm pump.

Also, the supply section <NUM> may also have a function as an adjustment section which adjusts the pressure of the liquid L held in the liquid holding section <NUM>. To be specific, if the liquid L is supplied from the supply section <NUM> toward the liquid holding section <NUM>, the pressure of the liquid L increases. In addition, if the supply section <NUM> suctions the liquid L from the liquid holding section <NUM>, the pressure of the liquid L decreases.

The detection unit <NUM> detects the pressures of the liquid L held in the liquid holding section <NUM>. For example, a semiconductor diaphragm type pressure sensor can be adopted for the detection unit <NUM>.

<FIG> are explanatory diagrams illustrating a state in which the liquid ejection unit <NUM> ejects the liquid L and are schematic diagrams illustrating a state in the vicinity of the ejection port 111a of the liquid holding section <NUM>.

<FIG> illustrates the liquid holding section <NUM> in a state being left to stands still. If the liquid L is supplied to the inside 111x of the liquid holding section <NUM>, a capillary phenomenon occurs in the liquid holding section <NUM> due to the surface tension of the liquid L. Thus, a force F1 for pulling up the liquid L in the liquid holding section <NUM> in the +z direction is applied to the liquid L.

On the other hand, the force of gravity is applied to the liquid L in the -z direction. Furthermore, a force is applied to the liquid L in the vicinity of the ejection port 111a from the ejection port 111a toward the outside in accordance with the pressure of the liquid L. Thus, a force F2 which pushes down the liquid L in the liquid holding section <NUM> in the -z direction is applied to the liquid L.

In the liquid holding section <NUM>, in a state in which the force F2 is smaller than the force F1, even through the lower end of the liquid holding section <NUM> is open, the liquid L is held in the inside 111x of the liquid holding section <NUM> without being discharged through the ejection port 111a.

Subsequently, as illustrated in <FIG>, the liquid L is supplied from the supply section <NUM> to the liquid holding section <NUM>. In the liquid ejection unit <NUM>, the liquid holding section <NUM> to the pressure adjustment section 120A are connected in a closed system. For this reason, if the liquid L is supplied from the supply section <NUM> to the liquid holding section <NUM>, in the liquid holding section <NUM>, the liquid L is pressurized in accordance with a supply pressure of the liquid L. Thus, in the liquid holding section <NUM>, a force F3 which pushes down the liquid L in the -z direction becomes larger than the force F2 in <FIG>.

At this time, if a state in which the force F1 is larger than the force F3 is provided, in the ejection port 111a of the liquid holding section <NUM>, the liquid L is held in the ejection port 111a. On the other hand, since the force F3 is larger than the force F2, the liquid L in the ejection port 111a is pushed out in the -z direction, projects, and forms a meniscus LM.

Subsequently, as illustrated in <FIG>, if the displacement member <NUM> displaces the liquid holding section <NUM>, an inertial force applied in the z direction is applied to the liquid L and the meniscus LM due to the vibration of the displacement member <NUM>. Thus, in the ejection port 111a, a force F4 which pushes down the meniscus LM of the liquid L in the -z direction becomes larger than the force F3 in <FIG>.

If the force F4 is larger than the force F1, a shape of the meniscus LM cannot be maintained in the ejection port 111a. In addition, as illustrated in <FIG>, the meniscus LM is separated from the ejection port 111a and flies as a liquid droplet L1.

If the supply section <NUM> is continuously driven, as illustrated in <FIG>, the liquid L is continuously supplied from the supply section <NUM> to the liquid holding section <NUM>. Furthermore, if the displacement member <NUM> is continuously driven, the liquid holding section <NUM> continuously vibrates in the z axis direction. For this reason, if the supply section <NUM> and the displacement member <NUM> are continuously driven, in the liquid holding section <NUM>, the phenomenon illustrated in <FIG> repeatedly occurs and it is possible to continuously eject a liquid droplet L1.

Here, the detection unit <NUM> of the pressure adjustment section 120A illustrated in <FIG> detects the pressure of the liquid L pressurized using the supply section <NUM>. When the liquid ejection device <NUM> is used, it is advisable that a correspondence relationship between the pressure of the liquid L and the state of the liquid droplet L1 to be ejected is checked in advance through a preliminary experiment. Thus, the pressure of the liquid L in which the liquid droplet L1 is enabled to be appropriately ejected may be checked.

Examples of the "state of the liquid droplet L1 to be ejected" include a volume of the liquid droplet L1, an adhering position of the liquid droplet L1 in the attachment section <NUM>, and the like.

Also, an appropriate pressure of the liquid L is input to the control unit <NUM> in advance as the pressure of the liquid L when the liquid is ejected. The control unit <NUM> adjusts the pressure of the liquid L on the basis of the detection result of the detection unit <NUM> so that the pressure of the liquid L approaches a predetermined set value of the ejecting pressure of the liquid L.

That is to say, when the detection result of the detection unit <NUM> is higher than the set pressure, the control unit <NUM> controls the supply section <NUM> so that the amount of liquid L to be supplied from the supply section <NUM> is reduced. Also, when the detection result of the detection unit <NUM> is lower than the set pressure, the control unit <NUM> controls the supply section <NUM> so that the amount of liquid L to be supplied from the supply section <NUM> is increased.

Thus, the liquid ejection unit <NUM> can appropriately adjust the pressure of the liquid L on the basis of the detection result of the detection unit <NUM> and eject the liquid droplet L1.

As described above, in the liquid ejection unit <NUM> in this embodiment, the pressure adjustment section 120A which adjusts the pressure of the liquid L held in the liquid holding section <NUM> and the displacement member <NUM> which displaces the liquid holding section <NUM> are configured to have different constitutions. Thus, the following effects are achieved.

First, a case in which the liquid ejection unit does not have the constitution configured to adjust the pressure of the liquid L as described above is considered. In this case, the pressure of the liquid L in the ejection port 111a of the liquid holding section <NUM> is determined in accordance with a height (a depth) from a liquid surface of the liquid L in the liquid holding section <NUM> to the ejection port. In such a case, when a highly viscous liquid L is to be ejected, it may be necessary to increase a size of the liquid holding section <NUM> and increase the height from the liquid surface to the ejection port.

On the other hand, the liquid ejection unit <NUM> in this embodiment includes the pressure adjustment section 120A configured to adjust the pressure of the liquid L held in the liquid holding section <NUM>. For this reason, also when the highly viscous liquid L is to be ejected, it is possible to appropriately adjust the pressure of the liquid L by adjusting the pressure applied to the liquid L of the liquid holding section <NUM> using the pressure adjustment section 120A. Thus, in the liquid ejection unit <NUM> in this embodiment, it is possible to reduce a size of a device.

Also, when a constitution in which the supply section <NUM> configured to supply the liquid L to the liquid holding section <NUM> adjusts the pressure of the liquid L as in the liquid ejection unit <NUM>, it is also possible to utilize this constitution as a dispenser configured to continuously discharge the liquid L from the liquid ejection unit <NUM> by continuously supplying the liquid L from the supply section <NUM>.

Furthermore, for example, a constitution in which a part of a flow path through which a liquid flows is deformed, a part of a liquid held in the liquid holding section is displaced, and a liquid is ejected may be considered for the liquid ejection unit. In this case, if a highly viscous liquid is to be ejected, it becomes necessary to deform a part of the flow path greatly or strongly. For example, if a piezoelectric element is adopted for a constitution in which the flow path is deformed, in order to greatly or strongly deform a part of the flow path, it may be necessary to increase a size of the piezoelectric element.

On the other hand, since the displacement member <NUM> and the pressure adjustment section 120A are separate bodies in the liquid ejection unit <NUM>, it is possible to independently control an operation of the pressure adjustment section 120A in the state of <FIG> and an operation of the displacement member <NUM> in the states of <FIG>. For this reason, for example, when liquids with different viscosities are ejected, when the driving conditions of the pressure adjustment section 120A are adjusted in accordance with the viscosities of the liquids, it is possible to appropriately eject the liquids by simply driving the displacement member <NUM> under a constant driving conditon.

Also, as illustrated in <FIG>, in the liquid ejection unit <NUM>, the displacement member <NUM> and the pressure adjustment section 120A share a force applied to eject the liquid L from the liquid holding section <NUM> (a force applied to change the force F2 to the force F4). For this reason, even with the small displacement member <NUM>, it is possible to appropriately eject the liquid L. Thus, in the liquid ejection unit <NUM> in this embodiment, it is possible to reduce the size of a device.

According to the liquid ejection unit <NUM> having the above-described constitution, it is possible to provide a liquid ejection unit which can appropriately eject a highly viscous liquid.

Also, according to the liquid ejection device <NUM> having the above-described constitution, since the above-described liquid ejection unit is provided, it is possible to appropriately eject a highly viscous liquid.

Although the pressure adjustment section 120A supplies the liquid L to the liquid holding section <NUM> using the supply section <NUM> and pressurizes the liquid L in this embodiment, the pressure adjustment of the liquid L using the pressure adjustment section 120A is not limited thereto. The pressure adjustment section 120A may suction the liquid L from the liquid holding section <NUM> and adjust the pressure of the liquid L to be decreased.

In this case, for example, first, when the inside of the liquid holding section <NUM> is set to a negative pressure using the pressure adjustment section 120A, the meniscus of the ejection port 111a is suctioned into the liquid holding section. After that, it is possible to eject a liquid droplet by displacing the displacement member <NUM> and displacing the liquid holding section <NUM> at a timing at which the meniscus naturally returns to the ejection port 111a or at a timing at which the inside of the liquid holding section <NUM> is set to a positive pressure by performing pressurizing using the pressure adjustment section 120A.

If the liquid L is ejected by driving the displacement member <NUM> in a state in which the pressure of the liquid L is reduced, a diameter of the generated liquid droplet L1 tends to become smaller than a diameter of the liquid droplet L1 of the liquid when the pressurized liquid L is ejected.

Also, although the liquid ejection device <NUM> in this embodiment has the plurality of liquid ejection units <NUM>, the present invention is not limited thereto. In addition, a constitution having only one liquid ejection unit <NUM> may be used.

Furthermore, although the displacement member <NUM> displaces the liquid L substantially parallel to the ejection direction of the liquid L in the liquid ejection unit <NUM> in this embodiment, the present invention is not limited thereto. Even if the displacement member <NUM> is configured to displace the liquid L in a direction intersecting the ejection direction of the liquid L, it is possible to appropriately eject a highly viscous liquid and it is possible to make a liquid ejection unit configured to solve the problems of the present invention.

<FIG> is an explanatory diagram of a liquid ejection unit and the liquid ejection device according to a second embodiment of the present invention and is a diagram corresponding to <FIG>. A liquid ejection unit <NUM> in this embodiment is partially the same as the liquid ejection unit <NUM> in the first embodiment. Therefore, constituent elements in this embodiment that are the same as those of the first embodiment will be denoted by the same reference symbols and a detailed description thereof will be omitted.

The liquid ejection unit <NUM> includes a liquid ejection head <NUM> and a pressure adjustment section 120B.

A liquid ejection device <NUM> in this embodiment has a constitution in which the liquid ejection unit <NUM> in the above-described liquid ejection device <NUM> is replaced with the liquid ejection unit <NUM>.

The pressure adjustment section 120B includes a supply section <NUM> and a detection unit <NUM>.

The supply section <NUM> is connected via a liquid holding section <NUM> and a pipe <NUM>. The pipe <NUM> can have the same constitution as the above-described first pipe 115a.

The detection unit <NUM> is an observation device configured to observe a state of a meniscus formed using an ejection port 111a. The "state of the meniscus" includes at least one selected from the group consisting of a shape and a volume of the meniscus and a formation position of the meniscus. Examples of the detection unit <NUM> include an imaging device configured to capture a meniscus and a laser measuring device configured to detect a position, a size, and a shape of a meniscus. It is possible to detect a movement state of a meniscus by continuously detecting a position of the meniscus. The "movement state of the meniscus" includes an amplitude and a phase of the vibration of the meniscus by driving a displacement member.

When the liquid ejection device <NUM> including the liquid ejection unit <NUM> is used, a correspondence relationship between a state of the meniscus and a pressure of a liquid L is checked in advance using a preliminary experiment.

The state of the meniscus changes in accordance with the pressure of the liquid L. Thus, even if the pressure of the liquid L is not directly measured, the liquid ejection unit <NUM> can indirectly detect the pressure of the liquid L by checking the state of the meniscus using the detection unit <NUM>.

Also, the correspondence relationship between a pressure of the liquid L and a state of the liquid droplet L1 to be ejected is checked in advance through a preliminary experiment.

An appropriate pressure of the liquid L is input to a control unit <NUM> in advance as the pressure of the liquid L when the liquid is ejected. Furthermore, the correspondence relationship between the state of the meniscus and the pressure of the liquid L is stored in advance in the control unit <NUM>. Such a control unit <NUM> indirectly detects the pressure of the liquid L from the state of the meniscus on the basis of the detection result of the detection unit <NUM> and adjusts the pressure of the liquid L to approach a predetermined set value of the ejecting pressure of the liquid L.

That is to say, when the pressure of the liquid L indirectly detected from the detection result of the detection unit <NUM> is higher than a set pressure, the control unit <NUM> controls the supply section <NUM> to reduce an amount of liquid L to be supplied from the supply section <NUM>. Also, when the pressure of the liquid L indirectly detected from the detection result of the detection unit <NUM> is lower than the set pressure, the control unit <NUM> controls the supply section <NUM> to increase the amount of liquid L to be suppied from the supply section <NUM>.

Thus, the liquid ejection unit <NUM> can appropriately adjust the pressure of the liquid L on the basis of the detection result of the detection unit <NUM> and eject a liquid droplet L1.

Although the detection unit <NUM> detects the state of the meniscus formed in an ejection port in this embodiment, the present invention is not limited thereto. The detection unit <NUM> may observe a state of a liquid droplet L1 ejected from the liquid holding section <NUM> when the liquid droplet L1 flies.

The "state of the liquid droplet L1 when the liquid droplet L1 flies" includes at least one selected from the group consisting of a shape and a volume of a liquid droplet L1, a speed of the liquid droplet L1, and a flight position of the liquid droplet L1. Examples of the detection unit <NUM> include an imaging device configured to capture a liquid droplet L1 and a laser measuring device configured to detect a size, a shape, and movement of the liquid droplet L1.

When the liquid ejection device <NUM> including the liquid ejection unit <NUM> is used, the correspondence relationship between a state of the liquid droplet L1 and a pressure of the liquid L is checked in advance using a preliminary experiment.

The state of the liquid droplet L1 changes in accordance with the pressure of the liquid L. Thus, even if the pressure of the liquid L is not direclty measured, the liquid ejection unit <NUM> can indirectly detect the pressure of the liquid L by checking the state of the liquid droplet L1 using the detection unit <NUM>.

Also, the correspondence relationship between a pressure of the liquid L and a state of the liquid droplet L1 to be ejected is checked in advance using a preliminary experiment.

An appropriate pressure of the liquid L is input to the control unit <NUM> in advance as the pressure of the liquid L when the liquid is ejected. Furthermore, a correspondence relationship between a state of the meniscus and a pressure of the liquid L is stored in the control unit <NUM> in advance. Such a control unit <NUM> indirectly detects the pressure of the liquid L from the state of the liquid droplet L1 on the basis of the detection result of the detection unit <NUM> and adjusts the pressure of the liquid L to appropach a predetermined set value of the ejecting pressure of the liquid L. A pressure adjustment method of the liquid L may be the same as an adjustment method after the above-described state of the meniscus is detected.

With the liquid ejection unit <NUM> configured as described above, it is possible to provide a liquid ejection unit which can appropriately eject a highly viscous liquid.

With the liquid ejection device <NUM> configured as described above, since the above-described liquid ejection unit is provided, it is possible to appropriately eject a highly viscous liquid.

Although both a device configured to detect a state of a meniscus and a device configured to detect a state of a liquid droplet L1 when the liquid droplet L1 flies have been described as the detection unit <NUM>, the liquid ejection device may include both of these two types of detection units <NUM>. In this case, the control unit <NUM> may indirectly detect the pressure of the liquid L on the basis of the detection result of the two types of detection units <NUM> and control the pressure of the liquid L.

<FIG> is an explanatory diagram of a liquid ejection unit and a liquid ejection device according to a third embodiment of the present invention and is a diagram corresponding to <FIG> and <FIG>. A liquid ejection unit <NUM> in this embodiment is partially the same as the liquid ejection unit in the above-described embodiments. Therefore, constituent elements in this embodiment that are the same as those of the above-described embodiments will be denoted by the same reference symbols and a detailed description thereof will be omitted.

A liquid ejection unit <NUM> includes a liquid ejection head <NUM> and a pressure adjustment section 120C.

The liquid ejection head <NUM> includes a liquid holding section <NUM>, a support section <NUM>, a displacement member <NUM>, and a pipe <NUM>. A pressure adjustment section 120A includes a supply section <NUM> and a detection unit <NUM>.

The liquid holding section <NUM> can adopt the same constitution as the above-described liquid holding section <NUM>.

The support section <NUM> supports the liquid holding section <NUM> in an attachable and detachable manner. The support section <NUM> can adopt various commonly known constitutions as long as they can support the liquid holding section <NUM>.

The support section <NUM> includes a support main body 162a configured to support the liquid holding section <NUM> and a screw 162x configured to fix the liquid holding section <NUM> to the support main body 162a.

The displacement member <NUM> can adopt the same constitution as the above-described displacement member <NUM>.

The pipe <NUM> connects the liquid holding section <NUM> to the supply section <NUM>.

The pressure adjustment section 120C includes a pressurizing section <NUM> and a detection unit <NUM>.

The pressurizing section <NUM> includes a soft section <NUM> and a pressing section <NUM>.

The soft section <NUM> is a tubular member which is provided by connecting the liquid holding section <NUM> to the pipe <NUM> and is in communication with the liquid holding section <NUM> and the pipe <NUM>. The soft section <NUM> includes a soft resin material as a forming material. Examples of the soft resin material include polyurethane, silicone rubber, and fluororesin.

The soft section <NUM> may be formed integrally with the pipe <NUM> or may be a separate member.

The pressing section <NUM> is a member provided on the soft section <NUM> and configured to press the soft section <NUM> in accordance with an instruction from a control unit <NUM>. The pressing section <NUM> can adopt various known constitutions as long as they can press the soft section <NUM>. For example, the pressing section <NUM> can have the same piezoelectric element as the above-described displacement member <NUM>.

In the pressurizing section <NUM>, the soft section <NUM> having the pressing section <NUM> provided therein is pressurized and compressed by supplying electricity to the pressing section (a piezoelectric element) <NUM> and compressing the pressing section <NUM>. Thus, a liquid L inside the soft section <NUM> and the liquid holding section <NUM> is pressurized and a part of the liquid L is pushed out through an ejection port 161x of the liquid holding section <NUM>.

In the liquid ejection unit <NUM> as described above, first, when the liquid L in the liquid holding section <NUM> is pressurized in the pressurizing section <NUM>, in the ejection port 161x of the liquid holding section <NUM>, a part of the liquid L held in the liquid holding section <NUM> is pushed out and a meniscus is formed.

Subsequently, a liquid droplet is ejected in the same driving manner as in <FIG> by driving the displacement member <NUM> and displacing the liquid holding section <NUM>.

In addition, with the liquid ejection device <NUM> configured as described above, since the above-described liquid ejection unit is provided, it is possible to appropriately eject a highly viscous liquid.

<FIG> is an explanatory diagram of a liquid ejection unit and a liquid ejection device according to a fourth embodiment of the present invention and is a diagram corresponding to <FIG>, <FIG>, and <FIG>. A liquid ejection unit <NUM> in this embodiment is partially the same as the liquid ejection unit in the above-described embodiment. Therefore, constituent elements in this embodiment that are the same as those of the above-described embodiment will be the same reference symbols and a detailed description thereof will be omitted.

A liquid ejection head <NUM> includes a liquid holding section <NUM>, a nozzle plate <NUM>, a displacement member <NUM>, and a pipe <NUM>.

The liquid holding section <NUM> is a tubular member whose lower end in the z axis direction is open. A liquid L is held inside the liquid holding section <NUM>. Furthermore, an upper portion of the liquid holding section <NUM> is connected to the pipe <NUM>.

A lower end portion 171x of the liquid holding section <NUM> is closed by the nozzle plate <NUM> and the displacement member <NUM>. A liquid L is held in a space surrounded by the liquid holding section <NUM>, the nozzle plate <NUM>, and the displacement member <NUM>.

The nozzle plate <NUM> is an annular member having an ejection port 172x. The nozzle plate <NUM> closes the lower end portion 171x of the liquid holding section <NUM>. The ejection port 172x communicates with the liquid holding section <NUM>.

A planar shape of the nozzle plate <NUM> and a size, a material, and a structure thereof when viewed in a plan view are not particularly limited and can be appropriately selected in accordance with the purpose.

Examples of a planar shape of an outer edge of the nozzle plate <NUM> include a circle, an ellipse, a rectangle, a square, and a rhombus. For example, when a shape of the outer edge of the nozzle plate <NUM> is circular, the nozzle plate <NUM> is an annular member.

An end portion of the nozzle plate <NUM> on the ejection port 172x side is not supported and can vibrate upward and downward. When the end portion of the nozzle plate <NUM> on the ejection port 172x side vibrates, a force is applied to the liquid L in the vicinity of the ejection port 172x downward and the liquid L is ejected through the ejection port 172x as a liquid droplet L1.

If a material of the nozzle plate <NUM> is too soft, the nozzle plate <NUM> easily vibrates. In addition, it is not easy to minimize the vibration immediately when ejecting is not performed. Thus, it is desirable to utilize a material having a certain degree of hardness.

Examples of the material of the nozzle plate <NUM> include metals, ceramics, polymer materials, and the like. Specific examples of the material of the nozzle plate <NUM> include stainless steel, nickel, aluminum, silicon dioxide, alumina, zirconia, and the like.

An opening shape of the ejection port 172x can be appropriately selected in accordance with the purpose. Examples of the opening shape of the ejection port 172x include a circle, an ellipse, a quadrangle, and the like. Among these, it is desirable that the opening shape of the ejection port 172x be circular.

An average opening diameter of the ejection port 172x is not particularly limited and can be appropriately selected in accordance with the purpose. When a liquid L to be ejected is a dispersion liquid, it is desirable that the opening shape of the ejection port 172x be twice or more a maximum diameter of a dispersoid such as cells dispersed in the liquid L to prevent clogging of the ejection port 172x with the dispersoid.

The displacement member <NUM> vibrates the nozzle plate <NUM> to eject a liquid droplet L1 through the ejection port 172x.

The displacement member <NUM> is arranged between the lower end portion 171x of the liquid holding section <NUM> and the nozzle plate <NUM> and closes the lower end portion 171x of the liquid holding section <NUM>.

The shape, the size, the material, and the structure of the displacement member <NUM> are not particularly limited and can be appropriately selected in accordance with the purpose.

The shape and an arrangement of the displacement member <NUM> are not particularly limited as long as the effects of the present invention are not impaired and can be appropriately designed in accordance with the shape of the nozzle plate <NUM>. For example, when the planar shape of the nozzle plate <NUM> is a circular planar shape, it is desirable to provide the displacement member <NUM> concentrically around the ejection port 172x.

It is desirable that a piezoelectric element be appropriately used as the displacement member <NUM>. As the piezoelectric element, a member having the same constitution as the piezoelectric element adopted for the displacement member <NUM> can be utilized.

In the liquid ejection unit <NUM> as described above, first, when a liquid L in the liquid holding section <NUM> is pressurized in the supply section <NUM>, in the ejection port 172x in the liquid holding section <NUM>, a part of the liquid L held in the liquid holding section <NUM> is pushed out and a meniscus is formed.

Subsequently, when a part of the liquid L held in the liquid holding section <NUM> is displaced by driving the displacement member <NUM>, a liquid droplet L1 is ejected.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the embodiments. The shapes, the combinations, and the like of the constituent elements illustrated in the above-described examples are merely examples and can be variously changed on the basis of design requirements and the like without departing from the gist of the present invention.

Among the constitutions of the liquid ejection unit and the liquid ejection device described in the above-described first to fourth embodiments, constitutions which achieve the same effects can be exchanged with each other as long as the effects of the present invention are not impaired.

For example, the liquid ejection device in the first embodiment may include the detection unit <NUM> included in the liquid ejection device described in the second to fourth embodiments instead of the detection unit <NUM>.

Similarly, the liquid ejection device described in the second to fourth embodiments may include the detection unit <NUM> included in the liquid ejection device in the first embodiment instead of the detection unit <NUM>.

Also, among the constitutions of the liquid ejection unit and the liquid ejection device described in the first to fourth embodiments, constitutions which achieve the same effects may be achieved may be repeatedly included as long as the effects of the present invention are not impaired.

For example, the liquid ejection device may include both of the detection unit <NUM> and the detection unit <NUM>. In this case, the control unit <NUM> may obtain the pressure of the liquid L on the basis of the detection result of both of the detection unit <NUM> and the detection unit <NUM> and control the pressure of the liquid L.

Claim 1:
A liquid ejection unit (<NUM>) comprising:
a liquid holding section (<NUM>) which has an ejection port (111a) through which a liquid is ejected and which holds the liquid;
a support section (<NUM>) configured to support the liquid holding section (<NUM>);
a pressure adjustment section (120A) which is configured to adjust a pressure of a liquid held in the liquid holding section (<NUM>); and
a displacement member (<NUM>) which is configured to displace the support section (<NUM>), and thereby to displace the liquid holding section (<NUM>) and at least a part of the liquid whose pressure is adjusted by the pressure adjustment section (120A) and eject the liquid from the liquid holding section (<NUM>),
wherein the displacement member (<NUM>) is configured to displace the liquid holding section (<NUM>) substantially parallel to an ejection direction of the liquid,
the liquid holding section (<NUM>) is a tubular member extending substantially parallel to the ejection direction of the liquid,
the liquid holding section (<NUM>) and the displacement member (<NUM>) are arranged to overlap when viewed in a plan view, and
a shape of the liquid holding section (<NUM>) when viewed in a plan view is smaller than a shape of the displacement member (<NUM>) when viewed in a plan view.