Patent Description:
In the related art, a liquid discharge head presses a movable valve body toward a discharge port from which ink is discharged to control ink discharge. <CIT> describes a liquid discharge head that includes a valve body having a recessed portion facing the discharge port. Such a liquid discharge head may have insufficient sealing performance of the discharge port due to foreign substances.

<CIT> discloses a method for the rapid manufacture of a three-dimensional workpiece from a molten material, in particular a molten metal, in which method the molten material is supplied to a compression chamber and delivered in drop form via an injector hole by means of a pressure pulse which is generated with the aid of a reciprocating piston that delimits the compression chamber. According to the invention, the compression chamber is degassed before manufacturing begins and/or during a pause in the manufacturing. In a first step, ultrasonic waves are coupled into the molten material in the compression chamber, which generate a force (FBjrk) that makes the gas in the molten material sink, and in a second step, after the ultrasonic excitation has ended, the piston is introduced deeper into the compression chamber in order to remove the rising gas via a conduit of the piston.

The present disclosure has an object to prevent deterioration of sealing performance of the discharge port (nozzle) due to foreign substances adhering to a surface of the valve body.

The invention is directed to a liquid discharge apparatus according to claim <NUM>.

As a result, according to the present disclosure, the deterioration of sealing performance of the nozzle due to the foreign substances adhering to the surface of the valve body can be prevented.

Embodiments of the present disclosure are described below with reference to drawings. In the description of the drawings, the same elements are denoted by the same reference codes and redundant descriptions thereof are omitted below.

First, a configuration of an inkjet head unit HU (hereinafter referred to as a head unit HU) as an example of a head unit according to the present embodiment is described with reference to <FIG> is a cross-sectional view illustrating a configuration of the head unit HU as an example of a head unit according to the present embodiment. As illustrated in <FIG>, the head unit HU includes an inkjet head <NUM> (hereinafter referred to as a head <NUM>) as an example of a liquid discharge head, and a drive controller <NUM> as an example of circuitry.

The head <NUM> includes a housing <NUM> with a hollow structure and a nozzle plate <NUM> disposed at one end of the housing <NUM>. The nozzle plate <NUM> has a nozzle <NUM> from which ink <NUM> as an example of a liquid is discharged. The housing <NUM> further has an inlet <NUM> from which the ink <NUM> is injected on a side face of the housing <NUM> in the vicinity of the nozzle <NUM>. The ink <NUM> injected from the inlet <NUM> is stored in a liquid chamber <NUM> in the housing <NUM>. The liquid chamber <NUM> is a space formed between the nozzle plate <NUM> and a seal <NUM> in the housing <NUM>. In the liquid chamber <NUM>, a valve body <NUM> is disposed adjacent to the nozzle plate <NUM> so as to face the nozzle <NUM>. A needle <NUM> as an example of a valve body coupler is coupled to the valve body <NUM>.

The seal <NUM> such as an O-ring fits onto the needle <NUM> so as to seal a gap between an inner face of the housing <NUM> and an outer circumferential surface of the needle <NUM>. Thus, the seal <NUM> prevents the ink <NUM> in the liquid chamber <NUM> from flowing toward a piezoelectric element <NUM> as an example of a driver.

The piezoelectric element <NUM> is disposed in a space adjacent to the liquid chamber <NUM> (above the liquid chamber <NUM> in <FIG>) via the seal <NUM>. The piezoelectric element <NUM> drives the needle <NUM> according to a signal (drive waveform) from the drive controller <NUM> to move the valve body <NUM> between a contact position at which the valve body <NUM> contacts the nozzle plate <NUM> and a separated position at which the valve body <NUM> is separated from the nozzle plate <NUM>. The valve body <NUM> is moved to open and close the nozzle <NUM>. The piezoelectric element <NUM> is made of zirconia ceramics, for example. The piezoelectric element <NUM> has a suitable shape to discharge the ink <NUM> in accordance with a volume of droplets of the ink <NUM>. The drive controller <NUM> is electrically connected to the piezoelectric element <NUM> to drive the piezoelectric element <NUM>.

A pressure mechanism that pressurizes and supplies the ink <NUM> to the head <NUM> and a moving mechanism that moves the head <NUM> are described below with reference to <FIG> and <FIG>. <FIG> is a diagram of a pressure mechanism <NUM> and a head moving mechanism <NUM>. <FIG> is a block diagram of a control system of the head unit HU, the pressure mechanism <NUM>, and the head moving mechanism <NUM>.

As illustrated in <FIG>, the ink <NUM> to be discharged from the head <NUM> is stored in a sealed ink tank (liquid tank) <NUM>. The ink tank <NUM> is connected to the inlet <NUM> of the head <NUM> via a tube <NUM>. Further, the ink tank <NUM> is connected to a compressor <NUM> via a pipe <NUM> including an air regulator <NUM>. The air regulator <NUM> adjusts a pressure of air compressed by the compressor <NUM> to a desired air pressure to supply the pressurized air from the compressor <NUM> to the ink tank <NUM>.

Accordingly, the ink <NUM> pressurized by the air is supplied to the inlet <NUM> of the head <NUM>. Thus, the ink <NUM> is discharged from the nozzle <NUM> when the valve body <NUM> opens the nozzle <NUM>. For example, the ink tank <NUM>, the pipe <NUM>, the air regulator <NUM>, and the compressor <NUM> function as a pressure mechanism <NUM> as an example of "a pressure mechanism" that pressurizes and supplies the ink <NUM> to the liquid chamber <NUM> (in other words, pressurizes the ink <NUM> in the liquid chamber <NUM>).

As illustrated in <FIG>, a portion (an upper portion in <FIG>) of the housing <NUM> of the head <NUM> is attached to a head holder <NUM>. The head holder <NUM> includes a driving device <NUM>. The driving device <NUM> is driven to move the head holder <NUM> along a rail <NUM> in directions indicated by arrow A and arrow B in <FIG>.

As a result, the head <NUM> attached to the head holder <NUM> also moves along the rail <NUM> in the directions indicated by arrow A and arrow B. The head holder <NUM>, the driving device <NUM>, and the rail <NUM> function as a head moving mechanism <NUM> as an example of "a moving mechanism" that moves the head <NUM> relative to an object onto which the ink <NUM> is discharged. The driving device <NUM> and the rail <NUM> may have a known mechanism such as a feed screw mechanism using a ball screw, a feed mechanism using a rack and pinion, or a feed mechanism using a power transmission belt and a pulley.

As illustrated in <FIG>, the head unit HU, the pressure mechanism <NUM>, and the head moving mechanism <NUM> are electrically connected to a controller <NUM>. The controller <NUM> may have, for example, a function of controlling the overall operation of a liquid discharge apparatus, which is described later, and may be connected to additional components other than the unit and mechanisms illustrated in <FIG>, if desired.

The controller <NUM> transmits an ink discharge cycle signal based on image data to the drive controller <NUM> of the head unit HU, for example. The controller <NUM> receives data indicating a state of the head <NUM> via the drive controller <NUM>. The controller <NUM> transmits a switching signal for switching pressurization of the ink <NUM> on and off to the pressure mechanism <NUM>. Further, the controller <NUM> transmits a movement signal for moving the head <NUM> to the head moving mechanism <NUM>.

The drive controller <NUM> of the head unit HU generates the drive waveform based on the ink discharge cycle signal received from the controller <NUM>, and drives the head <NUM> using the generated drive waveform. The head <NUM> opens and closes the nozzle <NUM> in accordance with the drive waveform from the drive controller <NUM> to discharge the ink <NUM>.

The pressure mechanism <NUM> switches the compressor <NUM> (or the air regulator <NUM>) on and off based on the switching signal received from the controller <NUM> to switch between a pressurized state and a non-pressurized state of the ink <NUM> to be supplied to the liquid chamber <NUM>. The head moving mechanism <NUM> drives the driving device <NUM> to move the head holder <NUM> in a predetermined direction by a predetermined distance based on the movement signal received from the controller <NUM>, and moves the head <NUM> to a desired position via the head holder <NUM>.

Operations of the head unit HU are described below with reference to <FIG>. <FIG> are graphs of the drive waveform of the head <NUM>. <FIG> illustrates the drive waveform for discharging the ink <NUM> from the head <NUM> (i.e., a liquid discharge waveform), and <FIG> illustrate the drive waveforms for vibrating the valve body <NUM> of the head <NUM> (i.e., a valve-body vibration waveform). <FIG>, and <FIG> are diagrams illustrating the operation of the head unit HU.

The drive controller <NUM> generates the liquid discharge waveform illustrated in <FIG> and the valve-body vibration waveform illustrated in <FIG>, and applies the liquid discharge waveform and the valve-body vibration waveform to the piezoelectric element <NUM>. A voltage V3 of the valve-body vibration waveform is larger than a voltage V1 of the liquid discharge waveform and the valve-body vibration waveform, and is smaller than a voltage V2 of the liquid discharge waveform. A voltage V4 of the valve-body vibration waveform is smaller than the voltage V3 and larger than the voltage V1.

In the liquid discharge waveform, illustrated in <FIG>, applied from the drive controller <NUM> to the piezoelectric element <NUM>, when the voltage V1 is applied to the piezoelectric element <NUM>, the valve body <NUM> is at the contact position at which the valve body <NUM> contacts the nozzle plate <NUM> as illustrated in <FIG>. In this state, since the valve body <NUM> closes the nozzle <NUM>, the ink <NUM> in the liquid chamber <NUM> is not discharged from the nozzle <NUM>.

When the voltage V2 is applied to the piezoelectric element <NUM>, the piezoelectric element <NUM> contracts as illustrated in <FIG>, and moves the needle <NUM> upward in <FIG>. As the needle <NUM> moves, the valve body <NUM> also moves to the separated position at which the valve body <NUM> is separated from the nozzle plate <NUM>, and a gap G is formed between a leading end of the valve body <NUM> and the nozzle <NUM>. The pressure mechanism <NUM> pressurizes and supplies the ink <NUM> into the liquid chamber <NUM> at a pressure of about <NUM> to <NUM> MPa, for example. The ink <NUM> in the liquid chamber <NUM> is discharged as ink droplets <NUM>' from the nozzle <NUM> as the gap G is formed.

Thus, when the liquid discharge waveform is applied to the piezoelectric element <NUM>, the valve body <NUM> moves between the contact position and the separated position (in directions indicated by arrow C in <FIG>), and the valve body <NUM> opens and closes the nozzle <NUM>. Thus, the drive controller <NUM> controls the valve body <NUM> to open and close the nozzle <NUM>, thereby discharging the ink <NUM> from the nozzle <NUM> (hereinafter, this control is also referred to as a "first operation").

In the valve-body vibration waveform, illustrated in <FIG>, applied from the drive controller <NUM> to the piezoelectric elements <NUM>, when the voltage V3 and the voltage V4 are alternately applied to the piezoelectric element <NUM>, the valve body <NUM> moves in directions indicated by arrows D in <FIG> via the piezoelectric element <NUM> and the needle <NUM>. In other words, the valve body <NUM> moves, at the separated position separated from the nozzle plate <NUM>, with an amplitude smaller than an amplitude when the ink <NUM> is discharged from the nozzle <NUM>. Since the voltage V3 and the voltage V4 in the valve-body vibration waveform are larger than the voltage V1 in the liquid discharge waveform illustrated in <FIG>, the valve body <NUM> is separated from the nozzle plate <NUM> when the voltage V3 or the voltage V4 is applied to the piezoelectric element <NUM>. This movement of the valve body <NUM> with the small amplitude causes foreign substances adhering to the surface of the valve body <NUM> to fall off.

Since the voltages V3 and V4 are smaller than the voltage V2 in the liquid discharge waveform as illustrated in <FIG>, the valve body <NUM> can be vibrated by a potential difference of the valve-body vibration waveform smaller than that of the liquid discharge waveform, so that heat generation and power consumption of the piezoelectric element <NUM> can be reduced.

That is, the drive controller <NUM> controls the valve body <NUM> to vibrate at the separated position separated from the nozzle plate <NUM>, causing the foreign substances adhering to the surface of the valve body <NUM> to fall off (hereinafter, this control is also referred to as a "second operation").

In the valve-body vibration waveform illustrated in <FIG>, the voltages V3 and V4 are set smaller than the voltage V2, but the voltages V3 and V4 can be set to arbitrary voltages at which the valve body <NUM> is positioned away from the nozzle plate <NUM>. For example, as illustrated in <FIG>, the voltage V3 of the valve-body vibration waveform may be the same as the voltage V2 of the liquid discharge waveform. The voltage V3 equal to the voltage V2 can simplifies a voltage control by the drive controller <NUM>.

As another example, the voltage V3 of the valve-body vibration waveform may be set larger than the voltage V2 of the liquid discharge waveform to vibrate the valve body <NUM> with a large amplitude at a position where the valve body <NUM> is sufficiently separated from the nozzle plate <NUM>. As a result, the foreign substances adhering to the valve body <NUM> can be removed more effectively.

In <FIG>, in the valve-body vibration waveform, the voltage V3 and the voltage V4 are alternately applied to the piezoelectric element <NUM>, but the shape of the waveform is not limited thereto. The valve-body vibration waveform may be any waveform, such as a sine wave or a triangular wave, that can vibrate the valve body <NUM> at the separated position separated from the nozzle plate <NUM>.

The drive controller <NUM> can selectively execute the first operation and the second operation described above. For example, the drive controller <NUM> executes the second operation before the first operation so as to start a liquid discharge operation after the foreign substances on the surface of the valve body <NUM> are removed.

In the above description, the piezoelectric element <NUM> has, but not limited to, a property of contracting in a direction away from the nozzle plate <NUM> when a voltage is applied. For example, the piezoelectric element <NUM> may have a property of expanding toward the nozzle plate <NUM> when a voltage is applied. In such a case, when the voltage V2 is applied to the piezoelectric element <NUM>, the piezoelectric element <NUM> expands, causing the valve body <NUM> to close the nozzle <NUM>, and when the voltage V1 is applied to the piezoelectric element <NUM>, the piezoelectric element <NUM> contracts, causing the valve body <NUM> to open the nozzle <NUM> to discharge the ink <NUM> pressurized and supplied into the liquid chamber <NUM> from the nozzle <NUM>.

As described above, the head unit HU according to the present embodiment includes the head <NUM> and the drive controller <NUM>. The head <NUM> includes the nozzle plate <NUM> having the nozzle <NUM>, the liquid chamber <NUM> to store the ink <NUM> to be discharged from the nozzle <NUM>, the valve body <NUM> in the liquid chamber <NUM>, the needle <NUM> coupled to the valve body <NUM>, and the piezoelectric element <NUM> to drive the needle <NUM> to move the valve body <NUM>. The drive controller <NUM> executes the first operation of the piezoelectric element <NUM> to move the valve body <NUM> between the contact position at which the valve body <NUM> contacts the nozzle plate <NUM> and the separated position at which the valve body <NUM> is separated from the nozzle plate <NUM> to open and close the nozzle <NUM>, and executes the second operation of the piezoelectric element <NUM> to vibrate the valve body <NUM> at the separated position.

In addition, as described above, the drive controller <NUM> selectively execute the first operation and the second operation. With this configuration, the foreign substances (e.g., components, particles, and the like in the ink <NUM>) adhering to the surface of the valve body <NUM> can be removed from the valve body <NUM>, thereby preventing deterioration of sealing performance of the nozzle <NUM> due the foreign substances adhering to the valve body <NUM>.

<FIG> is a diagram illustrating a configuration of the head unit HU according to a modification of the present disclosure. In this modification, the head unit HU further includes a liquid path (i.e., the tube <NUM>) communicating with the liquid chamber <NUM> and a vibrator <NUM> in the liquid path in addition to the configuration of the above-described embodiment.

A drive controller <NUM>' causes the vibrator <NUM> to apply vibrations to the ink <NUM> in the liquid path. As a result, the external vibrations are additionally transmitted to the valve body <NUM> moved (vibrated) in the directions indicated arrows D through the ink <NUM> to which the vibrations are applied. As a result, the foreign substances adhering to the valve body <NUM> can be removed more effectively.

<FIG> are diagrams illustrating an operation of the head unit HU in a liquid discharging apparatus. As described with reference to <FIG>, in the liquid discharge apparatus, the head moving mechanism <NUM> moves the head unit HU in the left-right direction in <FIG>.

When the drive controller <NUM> executes the second operation of vibrating the valve body <NUM> in the directions indicated by arrows D using the valve-body vibration waveform, as illustrated in <FIG>, the controller <NUM> causes the pressure mechanism <NUM> not to pressurize the ink <NUM> (i.e., the non-pressurized state). On the other hand, in the first operation of moving the valve body <NUM> between the contact position at which the valve body <NUM> contacts the nozzle plate <NUM> and the separated position at which the valve body <NUM> is separated from the nozzle plate <NUM> to discharge the ink <NUM> from the nozzle <NUM>, the controller <NUM> causes the pressure mechanism <NUM> to pressurize the ink <NUM> (i.e., the pressurized state). In the second operation, the controller <NUM> causes the pressure mechanism <NUM> to stop pressurizing the ink <NUM>.

With this configuration, when the ink <NUM> is discharged toward a discharge area of an object <NUM> onto which the ink <NUM> is discharged, the pressure is applied to the ink <NUM> so as to reliably discharge the ink <NUM> from the nozzle <NUM>. When the valve body <NUM> is vibrated to remove the foreign substances adhering to the valve body <NUM>, this configuration prevents the ink <NUM> from being unintentionally discharged toward the object <NUM>. In addition, consumption of the ink <NUM> can be reduced.

In this case, since the nozzle <NUM> is opened as illustrated in <FIG>, even if the ink <NUM> is not pressurized, the ink <NUM> may be unintentionally discharged due to pressure fluctuation in the head unit HU, electrical noise in the drive controller <NUM>, or the like.

For this reason, the controller <NUM> causes the pressure mechanism <NUM> to stop pressurizing the ink <NUM>, and further causes the head moving mechanism <NUM> to move the head unit HU to an evacuation position at which the nozzle <NUM> does not face the discharge area of the object <NUM> (i.e., the nozzle <NUM> faces a non-discharge area of the object <NUM> or does not face the object <NUM>). Then, the valve body <NUM> is moved away from the nozzle plate <NUM> and vibrated at the evacuation position where the head <NUM> faces the non-discharge area or does not face the object <NUM>. As a result, the ink <NUM> is not discharged onto the discharge area unintentionally.

Next, another embodiment of the present disclosure is described with reference to <FIG> are diagrams of the head unit HU according to another embodiment of the present disclosure. <FIG> is a cross-sectional view of the head unit HU with the nozzle <NUM> closed, and <FIG> is a cross-sectional view of the head unit HU with the nozzle <NUM> opened.

This embodiment is different from the above-described embodiment in that a reverse spring mechanism <NUM> as an example of a transmission mechanism is disposed between the needle <NUM> and the piezoelectric element <NUM>. In this embodiment, the piezoelectric element <NUM> has the property of expanding toward the nozzle plate <NUM> when a voltage is applied.

The reverse spring mechanism <NUM> is an elastic body formed of rubber, soft resin, or thin metal plate which is appropriately processed to be deformable. The reverse spring mechanism <NUM> includes a deformable portion 134a, a secured portion 134b, a guide portion 134c, and a bent side 134d.

The deformable portion 134a has a substantially trapezoidal cross-section. The deformable portion 134a contacts a base end (upper end in <FIG>) of the needle <NUM>. The secured portion 134b is secured to the deformable portion 134a and the inner wall of the housing <NUM>. The guide portion 134c couples the secured portion 134b and the piezoelectric element <NUM>. The bent side 134d couples the long side (corresponding to the lower base of the trapezoid) of the trapezoidal deformable portion 134a and the secured portion 134b.

With the reverse spring mechanism <NUM> having the above-described configuration, the piezoelectric element <NUM> expands when a predetermined voltage is applied to the piezoelectric element <NUM>. The guide portion 134c is pushed toward the nozzle <NUM> by the expanded piezoelectric element <NUM> in the direction indicated by arrow a in <FIG>.

This pushing force causes the deformable portion 134a to be retracted in the direction away from the nozzle <NUM> (direction indicated by arrows b in <FIG>). That is, the reverse spring mechanism <NUM> converts an expanding force of the piezoelectric element <NUM> into a retracting force to retract the needle <NUM>, and then transmits the retracting force to the needle <NUM>. In this embodiment, when a voltage is applied to the piezoelectric element <NUM>, the piezoelectric element <NUM> expands, and accordingly the valve body <NUM> opens the nozzle <NUM>. As a result, the head <NUM> discharges the ink droplets <NUM>' from the nozzle <NUM>.

As described above, in this embodiment, the reverse spring mechanism <NUM> is disposed between the needle <NUM> and the piezoelectric element <NUM>. The reverse spring mechanism <NUM> converts the expanding force of the piezoelectric element <NUM> into the retracting force to retract the needle <NUM>, which acts in the direction opposite to the expanding force, and then transmits the retracting force to the needle <NUM>. Also in this embodiment, the foreign substances adhering to the surface of the valve body <NUM> can be removed from the valve body <NUM> by the second operation described above, thereby preventing the deterioration of sealing performance of the nozzle <NUM> due the foreign substances adhering to the valve body <NUM>.

An application example in which the head <NUM> described above is used is describe with reference to <FIG> is a cross-sectional view of a head module <NUM> according to the application example. As illustrated in <FIG>, the head module <NUM> includes a plurality of heads <NUM> (eight heads <NUM> in the example illustrated in <FIG>) in a housing <NUM>.

The housing <NUM> includes a supply port <NUM> through which the ink <NUM> is supplied into the housing <NUM>, a supply path <NUM> connecting the supply port <NUM> and an inlet <NUM>, and a drain port <NUM> on the opposite side to the inlet <NUM> across a liquid chamber <NUM>. The housing <NUM> further includes a collection port <NUM> from which the ink <NUM> in the housing <NUM> is collected, and a collection path <NUM> connecting the collection port <NUM> and the drain port <NUM>.

The basic configuration of the plurality of heads <NUM> is the same as that described with reference to <FIG>, and corresponding elements in <FIG> are given reference numerals in the <NUM> series (e.g., a nozzle plate <NUM>, a valve body <NUM>, a needle <NUM>, a piezoelectric element <NUM>, a seal <NUM>, and the like).

In this application example, eight nozzles <NUM> of the eight heads <NUM> are arranged at substantially equal intervals in one direction (the left-right direction in <FIG>). Each of the heads <NUM> is disposed extending in the vertical direction so as to discharge the ink <NUM> downward from the nozzle <NUM> disposed at a lower portion of the head <NUM> in <FIG>.

The liquid chamber <NUM> of each head <NUM> penetrates the head <NUM> so that the ink <NUM> flows from one side (the left side in <FIG>) to the other side (the right side in <FIG>) in the direction of arrangement of the eight heads <NUM>. In other words, each head <NUM> has a configuration different from the above-described embodiment in that the drain port <NUM> is disposed on the side of the liquid chamber <NUM> opposite to the inlet <NUM>.

An applied case of the head module <NUM> described with reference to <FIG> is described below with reference to <FIG> and <FIG>. <FIG> is an overall perspective view of a carriage <NUM> on which the head module <NUM> is mounted, and <FIG> is an overall perspective view of a liquid discharge apparatus <NUM> including the carriage <NUM>. <FIG> illustrates the carriage <NUM> mounted on the liquid discharge apparatus <NUM> illustrated in <FIG> as viewed from the object <NUM> onto which a liquid such as the ink <NUM> is discharged.

The carriage <NUM> includes a head holder <NUM>. The carriage <NUM> is movable in the Z-direction (positive and negative directions) along a Z-axis rail <NUM> by driving force of a first Z-direction driver <NUM> which is described later. The head holder <NUM> is movable in the Z-direction (positive and negative directions) relative to the carriage <NUM> by driving force of a second Z-direction driver <NUM> which is described later. The head holder <NUM> includes a head fixing plate 80a for attaching the head module <NUM>.

In this applied case, the six head modules <NUM> described with reference to <FIG> are attached to the head fixing plate 80a and stacked one on another. Each of the head modules <NUM> includes the multiple nozzles <NUM>. The number and type of ink used in the head modules <NUM> is not particularly limited, and the ink may be different color for each head module <NUM> or may be the same color for all head modules <NUM>. For example, when the liquid discharge apparatus <NUM> is a coating apparatus using a single color, the ink <NUM> used in the head modules <NUM> may be the same color. Further, the number of head modules <NUM> is not limited to six, and may be more than six or less than six.

The head modules <NUM> are secured to the head fixing plate 80a such that a nozzle row, which is formed by the eight nozzles <NUM>, of each head module <NUM> intersects the horizontal plane (i.e., X-Z plane) and the multiple nozzles <NUM> are obliquely arrayed with respect to the X-axis as illustrated in <FIG>. Thus, the head module <NUM> discharges the ink <NUM> from the nozzles <NUM> in a direction (positive Z direction in the present embodiment) intersecting the direction of gravity.

The liquid discharge apparatus <NUM> such as a printing apparatus is installed to face the object <NUM> as illustrated in <FIG>. The liquid discharge apparatus <NUM> includes an X-axis rail <NUM>, a Y-axis rail <NUM> intersecting the X-axis rail <NUM>, and the Z-axis rail <NUM> intersecting the X-axis rail <NUM> and the Y-axis rail <NUM>.

The Y-axis rail <NUM> movably holds the X-axis rail <NUM> in the Y direction (positive and negative directions). The X-axis rail <NUM> movably holds the Z-axis rail <NUM> in the X direction (positive and negative directions). The Z-axis rail <NUM> movably holds the carriage <NUM> in the Z direction (positive and negative directions).

The liquid discharge apparatus <NUM> includes the first Z-direction driver <NUM> and an X-direction driver <NUM>. The first Z-direction driver <NUM> moves the carriage <NUM> in the Z direction along the Z-axis rail <NUM>. The X-direction driver <NUM> moves the Z-axis rail <NUM> in the X direction along the X-axis rail <NUM>. The liquid discharge apparatus <NUM> further includes a Y-direction driver <NUM> that moves the X-axis rail <NUM> in the Y direction along the Y-axis rail <NUM>. The liquid discharge apparatus <NUM> includes the second Z-direction driver <NUM> that moves a head holder <NUM> relative to the carriage <NUM> in the Z direction.

The liquid discharge apparatus <NUM> discharges the ink <NUM> from the head modules <NUM> (see <FIG>) mounted on the head holder <NUM> while moving the carriage <NUM> in the X direction, the Y direction, and the Z direction, thereby printing images on the object <NUM>. The movement of the carriage <NUM> and the head holder <NUM> in the Z direction is not necessarily parallel to the Z direction, and may be an oblique movement including at least a Z direction component.

Although the object <NUM> is flat in <FIG>, the object <NUM> may have a surface shape which is a nearly vertical surface, a curved surface with the large radius of curvature, and a surface having a slight unevenness, such as a body of a car, a truck, or an aircraft.

Examples of the liquid include a solution, a suspension, or an emulsion that contains, for example, a solvent, such as water or an organic solvent, a colorant, such as dye or pigment, a functional material, such as a polymerizable compound, a resin, or a surfactant, a biocompatible material, such as DNA, amino acid, protein, or calcium, or an edible material, such as a natural colorant.

These liquids can be used for, e.g., inkjet ink, coating paint, surface treatment solution, a liquid for forming components of electronic element or light-emitting element or a resist pattern of electronic circuit, or a material solution for three-dimensional fabrication.

The liquid discharge apparatus according to the present embodiment is not limited to the printing apparatus described above. For example, the head unit (or the head) according to the above-described embodiments of the present disclosure may be attached to a tip of a robot arm of a multi-articulated robot that can freely move like a human arm by a plurality of joints.

Claim 1:
A liquid discharge apparatus (<NUM>) configured to discharge the liquid onto an object (<NUM>) and comprising
a head unit (HU) comprising
a liquid discharge head (<NUM>) including:
a nozzle plate (<NUM>) having a nozzle (<NUM>);
a liquid chamber (<NUM>) configured to store a liquid to be discharged from the nozzle (<NUM>);
a valve body (<NUM>) in the liquid chamber (<NUM>), the valve body (<NUM>) being movable between a contact position at which the valve body (<NUM>) contacts the nozzle plate (<NUM>) to close the nozzle (<NUM>) and a separated position at which the valve body (<NUM>) is separated from the nozzle plate (<NUM>) to open the nozzle (<NUM>);
a valve body coupler (<NUM>) coupled to the valve body (<NUM>); and
a driver (<NUM>) configured to drive the valve body coupler (<NUM>) to move the valve body (<NUM>); and
circuitry (<NUM>) configured to
move the valve body (<NUM>) between the contact position and the separated position to open and close the nozzle (<NUM>) in a first operation; and
apply vibration to the valve body (<NUM>) while the valve body (<NUM>) is temporarily held at the separated position in a second operation, wherein the liquid discharge apparatus (<NUM>) further comprises a pressure mechanism (<NUM>) configured to pressurize the liquid in the liquid chamber (<NUM>),
characterized in that
the circuitry (<NUM>) is further configured to
execute the first operation while the pressure mechanism (<NUM>) applies a pressure to the liquid in the liquid chamber (<NUM>) to discharge the liquid from the nozzle (<NUM>); and
execute the second operation while the pressure mechanism (<NUM>) temporarily stops application of the pressure to the liquid in the liquid chamber (<NUM>).