Patent Description:
In the related art, a liquid discharge apparatus has a valve-type nozzle and includes a valve that opens and closes the valve-type nozzle (discharge port) from which a liquid is discharged. For example, <CIT> discloses a valve that includes a core and an elastic member disposed at a leading end of the core.

When the valve includes the elastic member at the leading end of the core, the elastic member is joined to the core. Examples of the joining include bonding by an adhesive, but the elastic member may be hardly bonded to the core depending on a material thereof. The elastic member may be joined to the core by mechanical joining such as crimping instead of bonding. However, the elastic member may be restrained by a crimped portion of the core, thereby deteriorating an elastic behavior of the elastic member.

<CIT> discloses a liquid discharge head according to the preamble of claim <NUM>.

To solve the above-described situation, the present disclosure has an object to provide a liquid discharge head including the elastic member joined to the core with a good elastic behavior and a liquid discharge apparatus incorporating the liquid discharge head.

The present invention is defined by the independent claim. Further embodiments of the present invention are described in the dependent claims.

As a result, according to the present disclosure, the elastic member can be joined to the core of the valve while maintaining a good elastic behavior.

With reference to drawings attached, descriptions are given below of embodiments of the present disclosure. In the drawings for illustrating embodiments of the present disclosure, elements or components identical or similar in function or shape are given identical reference numerals as far as distinguishable, and redundant descriptions are omitted.

<FIG> are external views of a liquid discharge head <NUM> according to an embodiment of the present disclosure. <FIG> is an overall perspective view of the liquid discharge head <NUM>, and <FIG> is an overall side view of the same liquid discharge head <NUM>. The liquid discharge head <NUM> according to the present embodiment discharges ink as a liquid.

The liquid discharge head <NUM> includes a first housing 11a and a second housing 11b. The second housing 11b is stacked on and joined to the first housing 11a. In the present embodiment, the first housing 11a is made of a material having high thermal conductivity, such as metal. The second housing 11b may be made of a different material from the first housing 11a, but is preferably made of the same material as the first housing 11a. In the following description, the two housings (i.e., the first housing 11a and the second housing 11b) are collectively referred to as a housing <NUM>.

The first housing 11a includes heaters <NUM> as heating devices on a front surface and a back surface thereof. The heater <NUM> is temperature controllable to heat the first housing 11a. The second housing 11b includes a connector <NUM> for communication of electric signals on an upper portion thereof.

<FIG> is an overall cross-sectional view of the liquid discharge head <NUM> according to the present embodiment, taken along line A-A in <FIG>. The first housing 11a holds a nozzle plate <NUM> as a discharge port substrate. The nozzle plate <NUM> has a nozzle <NUM> as a discharge port from which ink (liquid) is discharged. The first housing 11a further includes a channel <NUM> which is a liquid supply portion. The channel <NUM> sends the ink from a supply port <NUM> to a collection port <NUM> over the nozzle plate <NUM>.

The second housing 11b includes the supply port <NUM> and the collection port <NUM>. The supply port <NUM> and the collection port <NUM> are connected to one side and the other side of the channel <NUM>, respectively. A plurality of liquid discharge modules <NUM> is disposed between the supply port <NUM> and the collection port <NUM>. The liquid discharge module <NUM> discharges the ink in the channel <NUM> from the nozzle <NUM>. A restraint <NUM> is disposed above the liquid discharge module <NUM>.

Each of the liquid discharge modules <NUM> faces the corresponding nozzle <NUM> on the nozzle plate <NUM> held by the first housing 11a. In the present embodiment, the eight liquid discharge modules <NUM> correspond to the eight nozzles <NUM> arranged in a row, respectively. The number and an arrangement of the nozzles <NUM> and the liquid discharge modules <NUM> are not limited to eight as described above. For example, the number of nozzles <NUM> and the number of liquid discharge modules <NUM> may be one instead of plural. The nozzles <NUM> and the liquid discharge modules <NUM> may be arranged in multiple rows instead of one row.

In <FIG>, a housing seal <NUM> is disposed at a joint between the first housing 11a and the second housing 11b. In the present embodiment, the housing seal <NUM> is an O-ring that prevents ink leakage from the joint between the first housing 11a and the second housing 11b.

With the above-described configuration, the supply port <NUM> takes in the pressurized ink from the outside of the liquid discharge head <NUM>, feeds the ink in the direction indicated by arrow a1, and supplies the ink to the channel <NUM>. The channel <NUM> feeds the ink from the supply port <NUM> in the direction indicated by arrow a2. Then, the collection port <NUM> collects the ink that is not discharged from the nozzles <NUM> in the direction indicated by arrow a3. The nozzles <NUM> are arranged along the channel <NUM>.

The liquid discharge module <NUM> of the liquid discharge head <NUM> includes a valve <NUM> and a piezoelectric element <NUM> as a driving body. The valve <NUM> opens and closes the nozzle <NUM>. The piezoelectric element <NUM> drives the valve <NUM>. When a voltage is applied, the piezoelectric element <NUM> expands and contracts in a longitudinal direction, which is the vertical direction in <FIG>.

In the above-described configuration, when the piezoelectric element <NUM> moves the valve <NUM> upward in <FIG>, the nozzle <NUM> closed by the valve <NUM> is brought into an open state, and ink can be discharged from the nozzle <NUM>. When the piezoelectric element <NUM> moves the valve <NUM> downward in <FIG>, a leading end of the valve <NUM> seals the nozzle <NUM> to close the nozzle <NUM>, so that ink is not discharged from the nozzle <NUM>.

<FIG> is a partial front cross-sectional view of the liquid discharge head <NUM> illustrating a positional relation between the liquid discharge head <NUM> according to the present embodiment and the heater <NUM> (heating device). As described above, the first housing 11a includes the heater <NUM>. As indicated by a broken line in <FIG>, the heater <NUM> is disposed in the vicinity of the nozzles <NUM> so as to traverse the plurality of nozzles <NUM>.

The liquid discharge module <NUM> is described in detail below with reference to <FIG> is a cross-sectional view of one liquid discharge module <NUM>, and <FIG> is an enlarged view of a part of the liquid discharge module <NUM> illustrated in <FIG>. O-rings <NUM> are attached to an outer periphery of a shaft of the valve <NUM> at upper and lower two steps. The two O-rings <NUM> prevent a leakage of high-pressure ink. The liquid discharge module <NUM> includes the valve <NUM> and the piezoelectric element <NUM> described above, a fixing member <NUM>, a holder <NUM>, and a plug <NUM>.

The holder <NUM> has a driving body accommodating portion 35a therein, and accommodates and holds the piezoelectric element <NUM> in the driving body accommodating portion 35a. The holder <NUM> is made of elastically expandable metal that can expand or contract in the longitudinal direction of the piezoelectric element <NUM>. For example, steel use stainless (SUS) such as SUS304 or SUS316L can be used as the elastically expandable metal. The holder <NUM> is a frame in which multiple elongated members extending in the longitudinal direction are arranged around the piezoelectric element <NUM>. For example, four elongated members are arranged at intervals of <NUM>°. The piezoelectric element <NUM> is inserted inside the holder <NUM> through a gap between the elongated members of the holder <NUM>.

The longitudinal direction of the piezoelectric element <NUM> is the direction indicated by double-headed arrow A illustrated in <FIG>, which is the same as the longitudinal directions of the valve <NUM>, the liquid discharge module <NUM>, and the second housing 11b. The longitudinal direction indicated by double-headed arrow A is also the same as a moving direction of the valve <NUM>.

The valve <NUM> is coupled to one end of the holder <NUM> on a front side close to the nozzle <NUM>. The holder <NUM> has a bellows portion 35b on the front side close to the nozzle <NUM>. When the piezoelectric element <NUM> expands and contracts, the bellows portion 35b allows the front side of the holder <NUM> to expand and contract in the same direction as the longitudinal direction of the piezoelectric element <NUM>.

The fixing member <NUM> is coupled to the other end of the holder <NUM> on a base side opposite to the front side. In other words, the fixing member <NUM> is accommodated in an upper portion of the second housing 11b. The fixing member <NUM> has a through screw hole 33a extending in a radial direction of the liquid discharge module <NUM>. A positioning screw <NUM> is screwed into the through screw hole 33a from the outside of the second housing 11b.

The positioning screw <NUM> is inserted through a slotted hole 11b1, which is long in the longitudinal direction, formed in the upper portion of the second housing 11b. Accordingly, the positioning screw <NUM> is movable by a predetermined length in the longitudinal direction of the second housing 11b. The positioning screw <NUM> is tightened so as to position the fixing member <NUM> in the longitudinal direction.

As illustrated in <FIG>, a female screw hole 11b2 is formed in an upper opening of the second housing 11b. A plug <NUM> that contacts the restraint <NUM> illustrated in <FIG> is screwed into the female screw hole 11b2. The plug <NUM> contacts an upper end of the fixing member <NUM> positioned in the longitudinal direction by the positioning screw <NUM> to finally fix the position of the fixing member <NUM>.

A compression spring <NUM> is disposed at a lower end of the second housing 11b. The compression spring <NUM> presses the piezoelectric element <NUM> and the holder <NUM> holding the piezoelectric element <NUM> upward in <FIG>.

As illustrated in <FIG>, the valve <NUM> includes a core <NUM> and a seal member <NUM>. The core <NUM> is formed of metal such as stainless steel. The core <NUM> has a recess <NUM> on a leading end side. The recess <NUM> opens toward the nozzle <NUM>. Examples of a material of the seal member <NUM> includes an elastic member such as rubber or fluororesin, for example, polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE). Preferably, PTFE has a tensile elastic modulus of <NUM> GPa or more and <NUM>. <NUM> GPa or less, and PCTFE has the tensile elastic modulus of <NUM> GPa or more and <NUM> GPa or less. The tensile elastic modulus can be measured according to International Organization for Standardization (ISO) <NUM>: Plastics-Determination of tensile properties or Japanese Industrial Standards (JIS) K7161: Plastics-tensile properties test.

The seal member <NUM> has a first portion fitted into the recess <NUM> of the core <NUM> so as to attach the seal member <NUM> to the leading end (end on the side close to the nozzle <NUM>) of the core <NUM>. Further, the seal member <NUM> has a second portion projecting from the recess <NUM> of the core <NUM> toward the nozzle <NUM>. Thus, when the piezoelectric element <NUM> moves the valve <NUM> downward in the direction indicated by arrow a4 in <FIG>, the seal member <NUM> disposed at the leading end of the valve <NUM> (the core <NUM>) is pressed against the nozzle plate <NUM>. As a result, the nozzle <NUM> is sealed (closed) by the seal member <NUM>. On the other hand, when the piezoelectric element <NUM> moves the valve <NUM> upward, the seal member <NUM> is separated from the nozzle plate <NUM> to open the nozzle <NUM>.

As described above, the valve <NUM> moves between a contact position at which the seal member <NUM> (elastic member) is pressed against the nozzle plate <NUM> (discharge port substrate) and a separated position at which the seal member <NUM> is separated from the nozzle plate <NUM>, thereby opening and closing the nozzle <NUM> (discharge port).

In the liquid discharge module <NUM> according to the present example, the valve <NUM> includes the core <NUM> and the seal member <NUM> attached to the leading end of the core <NUM>. The core <NUM> and the seal member <NUM> are joined to each other so that the seal member <NUM> does not come off from the core <NUM>. An example of joining is bonding with an adhesive. However, when the seal member <NUM> is made of a material such as a fluororesin which is hard to be bonded, it is difficult to bond the seal member <NUM> by bonding. Another example of joining is mechanical joining such as crimping or swaging. The leading end of the core <NUM> is crimped to mechanically join the seal member <NUM> to the core <NUM>.

<FIG> is an enlarged cross-sectional view of the valve <NUM> having a joined structure by crimping. In the configuration illustrated in <FIG>, the leading end of the core <NUM> is crimped from the state indicated by the broken line to the state indicated by the solid line in <FIG>. As a result, the seal member <NUM> is restrained in the recess <NUM> so as to prevent the seal member <NUM> from falling off the recess <NUM>. However, in this case, since the seal member <NUM> is clamped at a position relatively close to the leading end of the seal member <NUM> by the crimped portion of the core <NUM>, the seal member <NUM> may be restricted from being elastically deformed (in particular, elastic deformation in a depth direction B of the recess <NUM> indicated by double-headed arrow B in <FIG>). As a result, the seal member <NUM> may not exhibit a good elastic behavior.

When the seal member <NUM> is formed by punching a sheet-shaped material, the seal member <NUM> is likely to be formed in a shape in which the width is smaller at the middle than at the top and at the bottom of the seal member <NUM> in the vertical direction as illustrated in <FIG>. With such a seal member <NUM>, when the seal member <NUM> is inserted into the recess <NUM>, a gap is generated between the seal member <NUM> and a side face 312b of the recess <NUM> as illustrated in <FIG>. From this state, when the leading end of the core <NUM> is crimped, the seal member <NUM> is deformed by crimping. Accordingly, the gap between the seal member <NUM> and the side face 312b of the recess <NUM> is increased, and another gap is also generated between the seal member <NUM> and a bottom face 312a of the recess <NUM>. As a result, the adhesiveness of the seal member <NUM> in the recess <NUM> decreases, and the posture of the seal member <NUM> becomes unstable. As illustrated in <FIG>, when the seal member <NUM> is pressed against the nozzle plate <NUM>, the seal member <NUM> is retracted (moved backward) from the state indicated by the broken line to the state indicated by the solid line in <FIG>. For this reason, a desired contact pressure of the seal member <NUM> with respect to the nozzle plate <NUM> may not be obtained, and a sealing performance may deteriorate.

A test was conducted to examine an elastic behavior of the seal member <NUM> clamped by crimping in the valve <NUM> described above. In this test, the seal member <NUM> having a diameter of <NUM> at the leading end was joined to the core <NUM> of the valve <NUM> by crimping. The valve <NUM> was attached to a tester, and the tester pressed the seal member <NUM> toward a quartz piezoelectric dynamometer <NUM> illustrated in <FIG> by a total of <NUM> in increments of <NUM> (i.e., pressurization). Thereafter, the tester retracted the seal member <NUM> by <NUM> at a time to remove the pressing load (i.e., depressurization). A displacement (pushing amount) and the pressing load of the valve <NUM> during pressurization (forward movement) and during depressurization (backward movement) were measured. <FIG> illustrates a relation between the measured displacement and the pressing load.

In <FIG>, the solid line indicates a load-displacement curve of the valve <NUM> during pressurization, and the broken line indicates a load-displacement curve of the valve <NUM> during depressurization. As illustrated in <FIG>, when the pressing load was <NUM> N at the start of pressurization, the displacement was <NUM>, and when the pressing load was removed, the displacement was about <NUM>. This is because when the seal member <NUM> is pressed against the dynamometer <NUM>, the seal member <NUM> is retracted and displaced into the recess <NUM>, and thus the leading end of the seal member <NUM> does not return to the original position (position before pressurization) even when the pressing load is removed. As a result, the leading end of the seal member <NUM> is retracted by about <NUM>. For this reason, although the elastic modulus (primary coefficient) of the seal member <NUM> is originally about <NUM> N/µm, the apparent elastic modulus of the seal member <NUM> decreases to about <NUM> N/µm which is smaller than <NUM> N/µm.

As described above, in the crimped-joint valve, since the leading end of the seal member <NUM> is clamped (restrained) by the core <NUM>, the elastic deformation of the seal member <NUM> is limited, and in addition, since the seal member <NUM> is retracted into the recess <NUM> during pressurization, the apparent elastic modulus decreases, so that the seal member <NUM> may not exhibit a desired elastic behavior. Moreover, such a deterioration of the elastic behavior is not constant and is affected by variations in the crimping process. For this reason, in order to maintain the sealing performance, a position of each valve <NUM> is adjusted based on the degree of the deterioration of the elastic behavior of the seal member <NUM> as follows.

<FIG> are diagrams illustrating a relation between the position (displacement) of the valve <NUM> and the discharge amount of ink discharged from the nozzle <NUM>. Ranges A to D in <FIG> correspond to positions of the valve <NUM> illustrated in <FIG>, respectively.

In the state illustrated in <FIG>, the leading end of the valve <NUM> (i.e., the seal member <NUM>) is positioned farthest from the nozzle <NUM>. At this time, the discharge amount of ink is maximum. When the leading end of the valve <NUM> approaches the nozzle <NUM> as illustrated in <FIG>, the discharge amount of ink decreases. When the leading end of the valve <NUM> further approaches the nozzle <NUM> and the seal member <NUM> comes into contact with the nozzle plate <NUM> as illustrated in <FIG>, the discharge amount of ink becomes substantially <NUM>. However, in this state, the nozzle <NUM> is not completely sealed. In order to completely seal the nozzle <NUM>, the leading end of the valve <NUM> (i.e., the seal member <NUM>) is pressed against the nozzle plate <NUM> as illustrated in <FIG> to compress the seal member <NUM>.

However, when the leading end of the valve <NUM> is pressed against the nozzle plate <NUM>, if the seal member <NUM> is retracted into the recess <NUM> as described above, an amount of compression of the seal member <NUM> may be insufficient, and thus the nozzle <NUM> may not be sealed. For this reason, a reference position (initial position) of the valve <NUM> is shifted forward by a distance by which the seal member <NUM> has been retracted so as to obtain a sufficient amount of compression of the seal member <NUM>.

However, when the reference position of the valve <NUM> is shifted in the forward direction, since the amount of expansion and contraction of the piezoelectric element is constant (for example, about <NUM> to <NUM>), the position of the valve <NUM> when the nozzle <NUM> is opened changes. The sufficient gap between the seal member <NUM> and the nozzle <NUM> is preferably, for example, <NUM> or more in order to obtain a predetermined discharge amount of ink when the nozzle <NUM> is opened. Accordingly, the position of the valve <NUM> is adjusted while maintaining both the sufficient gap between the seal member <NUM> and the nozzle <NUM> when the nozzle <NUM> is opened and the sufficient amount of compression of the seal member <NUM> when the nozzle <NUM> is closed. It is difficult to maintain both the position of the valve <NUM> when the nozzle <NUM> is opened and the position of the valve <NUM> when the nozzle <NUM> is closed, and it takes a large amount of labor and time to adjust the position of the valve <NUM>. Therefore, the present disclosure has an object to prevent the elastic behavior of the seal member <NUM> from deteriorating in order to facilitate adjusting the position of the valve <NUM>.

A joined structure of the seal member <NUM> according to the present disclosure is described below with reference to an example illustrated in <FIG>. As illustrated in <FIG>, in the present embodiment, the core <NUM> has the recess <NUM> including a retaining portion <NUM> that prevents the seal member <NUM> from falling off. The retaining portion <NUM> is wider than a portion of the recess <NUM> other than the retaining portion <NUM>. The term "width" refers to the size of the recess <NUM> in a width direction C indicated by double headed arrow C in <FIG>, which is orthogonal to the depth direction B indicated by double headed arrow B in <FIG>. Note that the "width" in the following description and drawings has the same meaning with a "width" in the "width direction C.

The retaining portion <NUM> is disposed between the bottom face 312a and a center of the recess <NUM> in the depth direction B. In particular, in the present example, the retaining portion <NUM> is disposed adjacent to the bottom face 312a. The recess <NUM> has a projection <NUM> having a triangular cross section on the bottom face 312a. The projection <NUM> is disposed at a center of the bottom face 312a and projects from the bottom face 312a toward the opening of the recess <NUM> (downward in <FIG>).

<FIG> illustrates the core <NUM> and the seal member <NUM> which are separated from each other. As illustrated in <FIG>, when the seal member <NUM> is separated from the core <NUM>, the seal member <NUM> has a columnar shape that is different from a shape of the recess <NUM>. When the seal member <NUM> having such a shape is inserted into the recess <NUM>, the inserted end face of the seal member <NUM> is pressed against the projection <NUM> of the recess <NUM>, and thus the seal member <NUM> is pushed and expanded in the width direction C. Accordingly, the retaining portion <NUM> is filled with a portion of the seal member <NUM> (the expanded portion), and the seal member <NUM> is fitted into the retaining portion <NUM> (see <FIG>).

As described above, in the present example, the seal member <NUM> is inserted into the recess <NUM>, and the portion of the seal member <NUM> is fitted into the retaining portion <NUM>. As a result, the seal member <NUM> is joined to the core <NUM> so as not to fall off the recess <NUM>. Therefore, in the present embodiment, the seal member <NUM> can be joined to the core <NUM> without crimping the leading end of the core <NUM>, and various situations associated with crimping as described above can be solved.

That is, in the present example, since the leading end of the seal member <NUM> is not clamped by the crimped leading end of the core <NUM>, the seal member <NUM> is elastically deformable without being restrained on the leading end side. In addition, since the gap due to crimping is not generated between the seal member <NUM> and the recess <NUM>, the posture of the seal member <NUM> is stable, and the seal member <NUM> is less likely to be retracted into the recess <NUM> during pressurization. Accordingly, since the seal member <NUM> is less likely to be retracted into the recess <NUM>, a decrease in apparent elastic modulus is also reduced.

In the present example, the retaining portion <NUM> is disposed adjacent to the bottom face 312a of the recess <NUM>. If the retaining portion <NUM> is disposed on the opening side of the recess <NUM>, elastic deformation of the seal member <NUM> (in particular, elastic deformation in the depth direction B of the recess <NUM>) may be restrained on the leading end side by a portion of the seal member <NUM> fitted into the retaining portion <NUM>. Regarding this point, in the present example, as illustrated in <FIG>, since the retaining portion <NUM> is disposed in a region d2 of a half of the recess <NUM> (i.e., a rear region) between the bottom face 312a and the center of the recess <NUM> in the depth direction B, the seal member <NUM> is not restrained on the leading end side thereof. That is, in the present example, since the seal member <NUM> is elastically deformable on the leading end side, the elastic behavior of the seal member <NUM> on the leading end side can be sufficiently maintained, and the amount of compression of the seal member <NUM> when pressed against the nozzle plate <NUM> can be sufficiently maintained.

As described above, in the present example, the elastic behavior and the amount of compression of the seal member <NUM> are sufficiently maintained, thereby reliably seal the nozzle <NUM>. In the present example, the seal member <NUM> is less likely to be retracted into the recess <NUM> when pressed against the nozzle plate <NUM>, thereby facilitating adjusting the position of the valve <NUM>. With the configuration according to the present example, the liquid discharge head having high reliability can be provided. Such a liquid discharge head facilitates adjusting the discharge amount of ink (i.e., the position of the valve <NUM>) and has a good sealing performance of the seal member <NUM> and the reliable joined structure between the seal member <NUM> and the core <NUM>.

<FIG> is a graph illustrating a relation between the displacement (pushing amount) and the pressing load of the valve <NUM> according to the present embodiment. In <FIG>, the solid line indicates a load-displacement curve of the valve <NUM> during pressurization, and the broken line indicates a load-displacement curve of the valve <NUM> during depressurization. The same test described above is conducted to examine the relation according to the present embodiment.

As illustrated in <FIG>, in the present example, the load-displacement curve (solid line) of the valve <NUM> during pressurization (forward movement) is not largely changed from the load-displacement curve (broken line) of the valve <NUM> during depressurization (backward movement), and the position of the leading end of the seal member <NUM> is substantially the same at the start of pressurization and at the end of depressurization. This result indicates that the seal member <NUM> is less likely to be retracted into the recess <NUM> and exhibits the good elastic behavior in the present embodiment. From the above, the configuration (joined structure) according to the present embodiment maintains the good sealing performance of the seal member <NUM> and enhance workability of position adjustment of the valve <NUM>.

In the present example, the retaining portion <NUM> is disposed adjacent to the bottom face 312a, but the retaining portion <NUM> is not necessarily disposed adjacent to the bottom face as long as the retaining portion <NUM> is disposed within the range d2 of the half of the recess <NUM> (i.e., the rear region) between the bottom face 312a and the center of the recess <NUM>. The retaining portion <NUM> has, but not limited to, the rectangular cross section as illustrated in <FIG>, and may be a triangular or semicircular cross section. As long as the retaining portion <NUM> is wider than the other portion (i.e., a portion of the recess <NUM> other than the retaining portion <NUM>), the width of the recess <NUM> may sharply increases from the other portion to the retaining portion <NUM> or may gradually increases from the other portion to the retaining portion <NUM>. The width of the retaining portion <NUM> preferably increases from the other portion to the retaining portion <NUM> at a right angle or an angle close to the right angle with respect to the depth direction B of the recess <NUM> (for example, a shape illustrated in <FIG>) to enable the retaining portion <NUM> to prevent the seal member <NUM> from falling off the recess <NUM>. The retaining portion <NUM> may be continuously disposed around the center of the bottom face 312a in a circumferential direction E indicated by double headed arrow E as illustrated in <FIG>, or may be partially disposed in the circumferential direction E as illustrated in <FIG>.

Modifications of the valve <NUM> are described below. In the following description, portions different from those of the above-described embodiment is mainly described. The other portions have basically the same configuration, and thus descriptions thereof is appropriately omitted.

In the modification illustrated in <FIG>, the shape of the projection <NUM> in the recess <NUM> is different from that of the above-described embodiment. In the above-described embodiment, the projection <NUM> has a conical shape or a pyramid shape having a triangular cross section (see <FIG>), but in the modification, the projection <NUM> has a hemispherical shape as illustrated in <FIG> or a spherical shape. As described above, even when the projection <NUM> has the hemispherical shape or the spherical shape, the projection <NUM> can push and expand the seal member <NUM> in the width direction C to assist the seal member <NUM> to be filled into the retaining portion <NUM>. In other modifications, the projection <NUM> may have another shape (a cylindrical shape, a prismatic shape, or the like).

<FIG> is a cross-sectional view of the seal member <NUM> which is separated from the core <NUM> according to another modification of the present example.

In the above-described embodiment, the seal member <NUM> has a columnar shape having a uniform width (see <FIG>), but the seal member <NUM> illustrated in <FIG> has a shape in which the width decreases from the top and the bottom toward the middle of the seal member <NUM> in the vertical direction in <FIG>. As described above, when the seal member <NUM> is formed by punching, the seal member <NUM> is likely to be formed in such a shape.

When the seal member <NUM> having such a shape is inserted into the recess <NUM>, a gap may be formed between the side face 312b of the recess <NUM> and the seal member <NUM> as illustrated in <FIG>. In this case, the adhesiveness of the seal member <NUM> to the recess <NUM> decreases, but a slight gap between the side face 312b of the recess <NUM> and the seal member <NUM> is allowable.

Also in this case, since the seal member <NUM> is joined to the core <NUM> without crimping, the seal member <NUM> is not restrained from elastically deforming by crimping and the gap between the seal member <NUM> and the recess <NUM> does not expand. Accordingly, the seal member <NUM> can exhibit the good elastic behavior. The seal member <NUM> is less likely to be retracted into the recess <NUM> when pressed against the nozzle plate <NUM>, thereby facilitating adjusting the position of the valve <NUM>. Also in this case, the good sealing performance of the seal member <NUM> can be maintained and the workability of position adjustment of the valve <NUM> may be enhanced.

In the example illustrated in <FIG>, the shapes of both the recess <NUM> and the seal member <NUM> are different from those of the above-described embodiment. Specifically, in the example illustrated in <FIG>, the width of the recess <NUM> gradually increases toward an opening rim 312c of the recess <NUM>, and the retaining portion <NUM> have a triangular cross section. On the other hand, the width of the seal member <NUM> gradually decreases toward the leading end thereof (in other words, toward the nozzle <NUM>).

As described above, the retaining portion <NUM> may have the triangular cross section. The width of the recess <NUM> gradually increases toward the opening rim 312c thereof and the width of the seal member <NUM> gradually decreases toward the leading end thereof. As a result, a clearance is formed between the seal member <NUM> and the side face 312b of the recess <NUM> at the opening rim 312c of the recess <NUM> and in the vicinity of the opening rim 312c (see <FIG>). Accordingly, in the example illustrated in <FIG>, when the leading end of the seal member <NUM> is pressed against the nozzle plate <NUM> as illustrated in <FIG>, even if the nozzle plate <NUM> is inclined, the seal member <NUM> is deformed following the inclination of the nozzle plate <NUM>. That is, the leading end of the seal member <NUM> is not restrained by the side face 312b of the recess <NUM>, and the clearance between the seal member <NUM> and the opening rim 312c allows the seal member <NUM> to be deformed following the inclination of the nozzle plate <NUM>.

As a result, when the seal member <NUM> is pressed against the nozzle plate <NUM>, the seal member <NUM> does not apply an excessive pressing load to the nozzle plate <NUM>. Accordingly, the nozzle plate <NUM> is prevented from being deformed, and thus ink is not obliquely discharged from the nozzle <NUM> of the nozzle plate <NUM>. Since the adhesiveness of the seal member <NUM> to the nozzle plate <NUM> can be maintained, the good sealing performance can be obtained. Further, since the gap between the seal member <NUM> and the nozzle <NUM> when the nozzle is opened can be sufficiently maintained, a predetermined discharge amount of ink can be discharged from the nozzle <NUM>.

The clearance between the seal member <NUM> and the side face 312b of the recess <NUM> is preferably disposed within a region d1 of a half of the recess <NUM> from the center of the recess <NUM> toward the opening of the recess <NUM> including at least the opening rim 312c (see <FIG>) to allow the leading end side of the seal member <NUM> to be deformed.

In the examples illustrated in <FIG>, the width of the recess <NUM> gradually increase toward the opening rim 312c, but the width of the recess <NUM> may increase stepwise as in the example illustrated in <FIG>. The width of the seal member <NUM> may be constant when the width of the recess <NUM> gradually increase toward the opening rim 312c as in the example illustrated in <FIG>. On the other hand, when the width of the seal member <NUM> decreases toward the leading end (toward the nozzle <NUM>), the width of the recess <NUM> in the region d1 of the half of the recess <NUM> may be constant as in the example illustrated in <FIG>. That is, at least one of the width of the recess <NUM> or the width of the seal member <NUM> changes (increases or decreases, respectively) to form the clearance between the seal member <NUM> and the side face 312b of the recess <NUM> in the region d1 of the half of the recess <NUM> including at least opening rim 312c.

The core <NUM> may be divided into two parts along the bottom face 312a of the recess <NUM> as in the example illustrated in <FIG>. This configuration allows the retaining portion <NUM> to be processed from the bottom face 312a side of the recess <NUM>, thereby facilitating forming the retaining portion <NUM>.

The retaining portion <NUM> may be a plurality of grooves <NUM> formed continuously in the depth direction B of the recess <NUM> as in the example illustrated in <FIG>. In this case, when the seal member <NUM> is inserted into the recess <NUM>, a portion of the seal member <NUM> is filled in the groove <NUM> to join the seal member <NUM> to the recess <NUM> as illustrated in <FIG>, thereby preventing the seal member <NUM> from falling off the recess <NUM>. The grooves <NUM> serving as the retaining portion <NUM> is disposed in the region d2 of the half of the recess <NUM> on the bottom face 312a side in the depth direction B, allowing the seal member <NUM> on the leading end side to exhibit the good elastic behavior similarly to the above-described embodiment. Accordingly, also in this example, the seal member <NUM> can be joined to the core <NUM> of the valve <NUM> while maintaining the elastic behavior of the seal member <NUM>. The grooves <NUM> may be multiple annular grooves formed independently of each other, or may be a single spiral groove formed continuously. The groove <NUM> may have a rectangular cross section or a semicircular cross section besides a triangular cross section as illustrated in <FIG>.

In the embodiment of the invention illustrated in <FIG>, a straight portion <NUM> in which the groove <NUM> is not formed is disposed between the groove <NUM> and the bottom face 312a. The straight portion <NUM> is a cylindrical face extending in the direction (depth direction B) orthogonal to the bottom face 312a. Accordingly, in the straight portion <NUM>, the width of the recess <NUM> does not change and is constant in the depth direction B. As described above, since the straight portion <NUM> is disposed between the groove <NUM> and the bottom face 312a, the grooves <NUM> can be easily formed without cutting the inner surface of the recess <NUM> up to the bottom face 312a.

A description is given below of a liquid discharge apparatus <NUM> including the liquid discharge head <NUM> described above. <FIG> are overall schematic views of the liquid discharge apparatus <NUM>. <FIG> is a side view, and <FIG> is a plan view of the liquid discharge apparatus <NUM>. The liquid discharge apparatus <NUM> is installed so as to face an object <NUM> onto which ink (liquid) is applied. The liquid discharge apparatus <NUM> includes an X-axis rail <NUM>, a Y-axis rail <NUM> intersecting the X-axis rail <NUM>, and a Z-axis rail <NUM> intersecting the X-axis rail <NUM> and the Y-axis rail <NUM>. In particular, in the present embodiment, the X-axis, Y-axis, and Z-axis rails <NUM>,<NUM>, and <NUM> extend in directions orthogonal to each other.

The Y-axis rail <NUM> movably holds the X-axis rail <NUM> along the Y-axis. The X-axis rail <NUM> movably holds the Z-axis rail <NUM> along the X-axis. The Z-axis rail <NUM> movably holds a carriage <NUM> along the Z-axis.

Further, the liquid discharge apparatus <NUM> includes a 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>. Further, the liquid discharge apparatus <NUM> includes a second Z-direction driver <NUM> that moves a head holder <NUM> relative to the carriage <NUM> in the Z direction.

The liquid discharge head <NUM> described above is attached to the head holder <NUM> mounted on the carriage <NUM> so that the nozzle <NUM> (see <FIG>) of the liquid discharge head <NUM> faces the object <NUM>. The liquid discharge apparatus <NUM> described above discharges ink, as an example of a liquid, from the liquid discharge head <NUM> attached to the head holder <NUM> toward the object <NUM> while moving the carriage <NUM> along the X-axis, the Y-axis, and the-Z axis to move the liquid discharge head <NUM>, thereby drawing images on the object <NUM>.

A description is given below of a configuration of an inkjet printer <NUM> as another example of the liquid discharge apparatus according to the present embodiment with reference to <FIG>. <FIG> is a diagram illustrating a configuration of the inkjet printer <NUM> as the example of the liquid discharge apparatus according to the present embodiment. <FIG> is a schematic perspective view of the inkjet printer <NUM> illustrated in <FIG> installed so as to face an object M onto which ink (liquid) is applied, such as an automobile. <FIG> is a schematic perspective view of the inkjet printer <NUM> illustrated in <FIG> installed in another arrangement so as to face the object M onto which ink (liquid) is applied, such as the automobile. <FIG> are diagrams illustrating images printed on a spherical surface of the object M by the inkjet printer <NUM>. <FIG> is a diagram illustrating the object M having the spherical surface onto which ink is discharged from a print head <NUM> by the inkjet printer <NUM>. <FIG> is a diagram illustrating a quadrangle image printed on the spherical surface by the inkjet printer <NUM>. <FIG> is a diagram illustrating two quadrangle images successively printed on the spherical surface by the inkjet printer <NUM>.

As illustrated in <FIG>, the inkjet printer <NUM> according to the present embodiment includes the print head <NUM>, an X-Y table <NUM>, a camera <NUM>, a controller <NUM>, a driver <NUM>, and the like.

The print head <NUM> is an inkjet liquid discharge head, such as the liquid discharge head <NUM> described above, that discharges ink (liquid) toward the surface the object M to be coated. The term "ink" in the present disclosure includes "paint. " The print head <NUM> includes a plurality of valve-type nozzles and discharges ink from each valve-type nozzle in a direction perpendicular to a discharge surface of the print head <NUM>. The discharge surface of the print head <NUM> from which ink is discharged is parallel to the X-Y plane formed by the movement of the X-Y table <NUM>, and the ink is discharged from each valve-type nozzle in the direction perpendicular to the X-Y plane. The ink is discharged from the respective valve-type nozzles in parallel to each other. Each valve-type nozzle communicates with an ink tank of a predetermined color. The ink tank is pressurized by a pressurizing device. A distance between each valve-type nozzle and the surface of the object M to be coated is preferably about <NUM> to discharge ink from each valve-type nozzle onto the surface of the object M as desired.

The X-Y table <NUM> includes a mechanism that moves the print head <NUM> and the camera <NUM> in the X and Y directions orthogonal to each other. Specifically, the X-Y table <NUM> includes an X-axis moving mechanism <NUM> that moves a slider holding the print head <NUM> and a camera <NUM>, which is described later, in the X direction, and a Y-axis moving mechanism <NUM> that moves the X-axis moving mechanism <NUM> in the Y direction while holding the X-axis moving mechanism <NUM> with two arms. The Y-axis moving mechanism <NUM> includes a shaft <NUM>, and a robot arm <NUM> holds and drives the shaft <NUM> to freely move the print head <NUM> to a predetermined position at which the print head <NUM> coats the object M with ink. For example, when the object M is the automobile, the robot arm <NUM> can position the print head <NUM> at the top of the automobile as illustrated in <FIG> or at the side of the automobile as illustrated in <FIG>. An operation of the robot arm <NUM> is controlled based on a program stored in advance in the controller <NUM>.

The camera <NUM> is an imaging device such as a digital camera that captures an image of the surface of the object M to be coated. The camera <NUM> is moved in the X direction and the Y direction by the X-axis moving mechanism <NUM> and the Y-axis moving mechanism <NUM>, and captures an image of the surface of the object M in a predetermined area at small constant intervals. Specifications such as characteristics of a lens and a resolution of the camera <NUM> are appropriately determined to enable the camera <NUM> to capture a plurality of subdivided images of a predetermined area of the surface of the object M. The controller <NUM> described below causes the camera <NUM> to capture the plurality of subdivided images of the surface of the object M continuously and automatically.

The controller <NUM> operates the X-Y table <NUM> based on image editing software S for editing an image captured by the camera <NUM> and a preset control program to control a printing operation (ink discharge operation) of the print head <NUM>. Examples of the controller <NUM> includes a so-called microcomputer, and the controller <NUM> includes a storage device that records and stores various programs, data of captured images, and data of images to be printed, a central processing unit that executes various processing according to the programs, an input device such as a keyboard and a mouse, and a digital versatile disk (DVD) player if desired. The controller <NUM> further includes a monitor <NUM>. The monitor <NUM> displays input information to the controller <NUM>, a processing result by the controller <NUM>, and the like.

For example, the print head <NUM> discharges ink from each nozzle <NUM> to form a two-dimensional quadrangular image on the spherical surface of the object M by inkjet method in the direction illustrated in <FIG>. Since the print head <NUM> discharges the ink from each nozzle <NUM> in a direction perpendicular to the print head <NUM>, a printed image 252a printed on the surface of the object M has a quadrangular shape with a deformed (bent) periphery as illustrated in <FIG> without image processing. When an image 252b is printed adjacent to the printed image 252a on the surface of the object M that is not flat, a non-printed area <NUM> may be formed between the image 252b and the printed image 252a on the object M as illustrated in <FIG>.

In the present embodiment, when an image is printed on the surface of the object M that is not flat, the controller <NUM> performs image processing on data of the plurality of subdivided images captured by the camera <NUM> using image processing software, and generates a composite print surface onto which the surface of the object M is projected. The controller <NUM> edits an image to be printed on the surface of the objects so that the image to be printed is continuously connected to a printed image that has already been printed on the surface of the object M at the edges of the image to be printed and the printed image on the composite print surface to create an edited image to be printed.

The controller <NUM> edits the image 252b so as to match the image 252b with the composite print surface not to form the non-printed area <NUM>, and creates the edited image to be printed. The print head <NUM> discharges ink onto the surface of the object M based on the created edited image to be printed, thereby printing the image 252b adjacent to the printed image 252a without a gap (i.e., the non-printed area <NUM>) between the image 252b and the printed image 252a. The controller <NUM> controls the driver <NUM> to cause the camera <NUM> to capture the plurality of subdivided images and to cause the print head <NUM> to discharge ink from each nozzle to print an image on the object M.

In the present disclosure, the term "liquid discharge apparatus" includes a liquid discharge head and drives the liquid discharge head to discharge liquid. The term "liquid discharge apparatus" used here includes, in addition to apparatuses to discharge liquid to materials onto which liquid can adhere, apparatuses to discharge the liquid into gas (air) or liquid.

The "liquid discharge apparatus" may further include devices relating to feeding, conveying, and ejecting of the material onto which liquid can adhere and also include a pretreatment device and an aftertreatment device.

The "liquid discharge apparatus" may be, for example, an image forming apparatus to form an image on a sheet by discharging ink, or a three-dimensional apparatus to discharge fabrication liquid to a powder layer in which powder material is formed in layers to form a three-dimensional object.

The "liquid discharge apparatus" is not limited to an apparatus that discharges liquid to visualize meaningful images such as letters or figures. For example, the liquid discharge apparatus may be an apparatus that forms meaningless images such as meaningless patterns or an apparatus that fabricates three-dimensional images.

The above-described term "material onto which liquid can adhere" serves as the object onto which liquid is applied as described above and represents a material on which liquid is at least temporarily adhered, a material on which liquid is adhered and fixed, or a material into which liquid is adhered to permeate. Specific examples of the "material onto which liquid can adhere" include, but are not limited to, a recording medium such as a paper sheet, recording paper, a recording sheet of paper, a film, or cloth, an electronic component such as an electronic substrate or a piezoelectric element, and a medium such as layered powder, an organ model, or a testing cell. The "material onto which liquid can adhere" includes any material to which liquid adheres, unless particularly limited.

Examples of the "material onto which liquid can adhere" include any materials to which liquid can adhere even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramic.

The term "liquid discharge apparatus" may be an apparatus to relatively move the liquid discharge head and the material onto which liquid can adhere. However, the liquid discharge apparatus is not limited to such an apparatus. For example, the liquid discharge apparatus may be a serial head apparatus that moves the liquid discharge head or a line head apparatus that does not move the liquid discharge head.

Claim 1:
A liquid discharge head (<NUM>) comprising:
a nozzle plate (<NUM>) having a discharge port (<NUM>) from which a liquid is discharged; and
a valve (<NUM>) facing the nozzle plate (<NUM>), the valve (<NUM>) configured to open and close the discharge port (<NUM>), the valve (<NUM>) including:
a core (<NUM>); and
an elastic member (<NUM>) attached to the core (<NUM>),
wherein the core (<NUM>) has a recess (<NUM>), and
the recess (<NUM>) has:
an opening rim (312c) on a leading end of the core (<NUM>), the opening rim (312c) defining an opening of the recess (<NUM>), and the opening opening toward the discharge port (<NUM>) in a depth direction of the recess (<NUM>);
a bottom face (312a) opposite to the opening rim (312c) in the depth direction; and
a retaining portion (<NUM>) having a width wider than a width of a portion other than the retaining portion (<NUM>) of the recess (<NUM>) in a width direction orthogonal to the depth direction, the retaining portion (<NUM>) disposed in a rear region between the bottom face (312a) and a center of the recess (<NUM>) in the depth direction, and
the elastic member (<NUM>) includes:
a first portion fitted into the recess (<NUM>); and
a second portion projecting from the opening of the recess (<NUM>) toward the discharge port (<NUM>) in the depth direction,
characterized in that
the retaining portion (<NUM>) has a plurality of grooves (<NUM>) in the rear region, the plurality of grooves (<NUM>) extending in the depth direction, and
the recess (<NUM>) further has a straight portion (<NUM>) between the plurality of grooves (<NUM>) and the bottom face (312a), the straight portion (<NUM>) having a width constant in the depth direction.