Patent Description:
In a liquid ejection head that ejects a liquid such as an ink, the amount of heat generated by a piezoelectric material, such as lead zirconate titanate (PZT), increases as the driving frequency increases. In order to efficiently control the temperature, it is usually necessary to provide a temperature control fluid flow path near the piezoelectric material.

In addition, in such liquid ejection heads if the resistance value of a common electrode used in driving ejections increases, latch-up of a driver IC may occur, which leads to a failure of the liquid ejection head. Since an increase in the area occupied by the common electrode reduces the resistance value of the common electrode, it is common for electrodes or portions thereof to be on both sides of the liquid ejection head substrate.

However, with such an arrangement, the temperature control fluid (e.g., cooling water) may flow over the common electrode portion provided on the back surface of the substrate, so that there is a concern that the common electrode may be corroded by this interaction with the temperature control fluid. It is noted that corrosion may be a problem for the common electrode or any other electrode in contact with any liquid/fluid, whether used as the temperature control fluid or not. Thus, even in a liquid ejection head in which an electrode portion other than the common electrode is provided on the back surface of the substrate, there remains a concern with possible corrosion.

<CIT> discloses a liquid ejection head without a temperature control fluid flow path.

The present invention concerns in general the prevention of electrode corrosion in a liquid ejection head.

A liquid ejection head according to appended claims is provided.

Hereinafter, a liquid ejection head <NUM> and a liquid ejection apparatus <NUM> incorporating the liquid ejection head <NUM> will be described with reference to <FIG>. <FIG> is a perspective view illustrating a configuration of the liquid ejection head <NUM> according to the embodiment. <FIG> is a bottom view illustrating the configuration of the liquid ejection head <NUM>. <FIG> is an exploded perspective view of the liquid ejection head <NUM>. <FIG> is a cross-sectional view illustrating a configuration of a head body <NUM>. <FIG> is a bottom view of the liquid ejection head. <FIG> is a cross-sectional view illustrating a portion of the head body. <FIG> is a bottom view illustrating the configuration of the liquid ejection head <NUM> with a nozzle plate <NUM> omitted. <FIG> is a plan view illustrating the configuration of the back side of a substrate <NUM>. <FIG> and <FIG> are cross-sectional views illustrating a configuration of a portion of the head body <NUM>. <FIG> is a bottom view illustrating the configuration of a manifold <NUM>, and <FIG> is a plan view illustrating the configuration of a shielding member <NUM>. <FIG> is an explanatory diagram illustrating the configuration of the liquid ejection apparatus <NUM>. In the figures, X, Y, and Z indicate three directions perpendicular to each other. It is noted that, in each figure, for the sake of description, aspects may be illustrated as enlarged, reduced, or omitted as appropriate.

The liquid ejection head <NUM> is, for example, a shear-mode inkjet head provided in the liquid ejection apparatus <NUM>, such as an inkjet recording apparatus illustrated in <FIG>. The liquid ejection head <NUM> has, for example, an independent drive structure where pressure chambers <NUM> and air chambers <NUM> are alternately provided. The liquid ejection head <NUM> is provided in a head unit <NUM> including a supply tank <NUM> as a liquid container provided in the liquid ejection apparatus <NUM>.

The liquid ejection head <NUM> is supplied with ink or other liquid stored in the supply tank <NUM>. The ink is also referred to as a first liquid. It is noted that the liquid ejection head <NUM> may be a non-circulation type head that does not circulate the ink or may be a circulation type head through which the ink circulates. In the present embodiment, the liquid ejection head <NUM> will be described by using an example of a non-circulation type head. The liquid ejection head <NUM> is connected to a temperature control device <NUM> provided in the liquid ejection apparatus <NUM> and is supplied with a temperature control fluid (also referred to as a second liquid) for controlling temperature in the liquid ejection head <NUM> and/or the ink.

As illustrated in <FIG>, the liquid ejection head <NUM> includes a head body <NUM>, a manifold unit <NUM>, a temperature control flow path unit <NUM>, a circuit board <NUM>, and a cover <NUM>. For example, the liquid ejection head <NUM> is a side shooter type, four-row integrated structure head having a pair of head bodies <NUM>, each head body <NUM> having a pair of actuators <NUM>.

The head body <NUM> ejects liquid (e.g., ink). The head body <NUM> includes a substrate <NUM>, a frame <NUM>, an actuator <NUM> having the plurality of pressure chambers <NUM> and the plurality of air chambers <NUM>, and a nozzle plate <NUM>.

The head body <NUM> has a common liquid chamber <NUM> communicating with (connected to) the plurality of pressure chambers <NUM> of the actuator <NUM>. A primary side of the plurality of pressure chambers <NUM> is the upstream side of the plurality of pressure chambers <NUM> in a liquid flowing direction. A secondary side of the plurality of pressure chambers <NUM> is the downstream side of the plurality of pressure chambers <NUM> in the liquid flowing direction.

In addition, the head body <NUM> has an electrode portion formed from an electrode film formed on the substrate <NUM> and the actuator <NUM>. Specifically, the head body <NUM> has, as electrode portions, a plurality of individual electrodes <NUM> respectively driving the plurality of pressure chambers <NUM> of the actuator <NUM>, and at least one common electrode <NUM> for the plurality of pressure chambers <NUM> as a group.

In the present example, each head body <NUM> has two actuators <NUM> and the common liquid chamber <NUM> has one first common liquid chamber <NUM> and two second common liquid chambers <NUM>. The common liquid chamber <NUM> includes, for example, the first common liquid chamber <NUM> communicating with primary side openings (inlets of the pressure chambers <NUM>) of the plurality of pressure chambers <NUM> of an actuator <NUM> and the second common liquid chamber <NUM> communicating with secondary side openings (outlets of the pressure chamber <NUM>) of the plurality of pressure chambers <NUM> of the actuator <NUM>.

The substrate <NUM> is formed in a rectangular plate shape from a ceramic material such as alumina. The substrate <NUM> has a front surface <NUM> which is a polished surface and a back surface <NUM>. The substrate <NUM> is formed, for example, in a rectangular shape elongated in one direction (X direction). A third electrode portion <NUM> (which is a portion of the plurality of individual electrodes <NUM>) and a third electrode portion <NUM> (which is a portion of one common electrode <NUM>) are formed on the front surface <NUM> of the substrate <NUM>. The pair of actuators <NUM> are provided on the front surface <NUM> of the substrate <NUM> to be aligned in a lateral direction (Y direction) of the substrate <NUM>. The substrate <NUM> has one supply port <NUM>, which is a hole through which the ink flows, and a plurality of discharge ports <NUM>, which are holes through which the ink flows for discharge. The supply port <NUM> and the discharge port <NUM> are through-holes penetrating the substrate <NUM>.

The supply port <NUM> is an inlet for supplying the ink to the first common liquid chamber <NUM>. The supply port <NUM> is a through-hole formed in the center of the substrate <NUM> in the lateral direction. The supply port <NUM> extends along the longitudinal direction of the substrate <NUM>. In other words, the supply port <NUM> is, for example, an elongated hole or slot elongated in the longitudinal direction of the actuator <NUM> and the first common liquid chamber <NUM>. The supply port <NUM> is provided between the pair of actuators <NUM> and opens at the position facing the first common liquid chamber <NUM>.

A fourth electrode portion <NUM> (which is a portion of the common electrode <NUM>) is formed on an inner wall surface of the supply port <NUM>.

The discharge port <NUM> is an outlet for discharging the ink from the first common liquid chamber <NUM>, the pressure chamber <NUM>, and the second common liquid chamber <NUM>. A plurality of (for example, four) discharge ports <NUM> are provided. Each discharge port <NUM> is, for example, between the first common liquid chamber <NUM> and one of the second common liquid chambers <NUM> and adjacent to both end portions of the pair of actuators <NUM> in the longitudinal direction. It is noted that the plurality of discharge ports <NUM> may be provided in the second common liquid chamber <NUM> in some examples.

The actuator <NUM> and the frame <NUM> are provided on the substrate <NUM>. The inside of the frame <NUM> serves as the liquid contact area where the ink can be present, and outside of the frame <NUM> is a mounting area to which various electronic components can be connected.

The frame <NUM> is fixed to one side of the substrate <NUM> with adhesive or the like. The frame <NUM> surrounds the supply port <NUM>, the plurality of discharge ports <NUM>, and the actuator(s) <NUM> provided in or on the substrate <NUM>.

For example, the frame <NUM> is formed in a rectangular frame shape. The frame <NUM> may have a stepped structure where a portion of the front surface is recessed. The pair of actuators <NUM>, the supply port <NUM>, and the four discharge ports <NUM> are arranged inside the opening of the frame <NUM>. The frame <NUM> surrounds the actuator <NUM> between the nozzle plate <NUM> and the substrate <NUM> and is configured to retain liquid inside.

The pair of actuators <NUM> are adhered to the front surface <NUM> of the substrate <NUM>. The pair of actuators <NUM> are in separate rows with the supply port <NUM> interposed therebetween. Each actuator <NUM> is formed in a plate shape elongated in one direction. The actuators <NUM> are arranged inside the opening of the frame <NUM> and adhered to the front surface <NUM> of the substrate <NUM>.

The actuator <NUM> has pressure chambers <NUM> arranged at equal intervals in the longitudinal direction and he air chambers <NUM> arranged at equal intervals in the longitudinal direction between otherwise adjacent pressure chambers <NUM>. In other words, the actuator <NUM> has a plurality of pressure chambers <NUM> and air chambers <NUM> that are alternately arranged with each other along the longitudinal direction. The plurality of pressure chambers <NUM> and the plurality of air chambers <NUM> extend in a direction intersecting an alignment direction, for example, in the lateral direction of the actuator <NUM>.

A top surface of the actuator <NUM> opposite to the substrate <NUM> is adhered to the nozzle plate <NUM>. The actuators <NUM> are arranged to be aligned at equal intervals in the longitudinal direction, and the plurality of grooves are formed along a direction perpendicular to the longitudinal direction. The plurality of grooves form the pressure chambers <NUM> and air chambers <NUM>. In other words, the actuator <NUM> has a plurality of piezoelectric bodies <NUM> as walls (sidewalls) of the grooves between the piezoelectric bodies <NUM>. The piezoelectric bodies <NUM> are thus arranged at equal intervals in the longitudinal direction and can function as drive elements for changing the volume of the pressure chambers <NUM> when a drive voltage is applied.

For example, the width of the actuator <NUM> in the lateral direction gradually increases from a top side toward the substrate <NUM> side. A cross-sectional shape of the cross section along a direction (lateral direction) perpendicular to the longitudinal direction of the actuator <NUM> is formed in a trapezoidal shape. That is, the actuator <NUM> has an inclined surface <NUM> that is inclined on the side portion in the lateral direction. The side portion (inclined surface <NUM>) is arranged to face the first common liquid chamber <NUM> and the second common liquid chamber <NUM>. A second electrode portion <NUM> which is a portion of the plurality of individual electrodes <NUM> and a second electrode portion <NUM> which is a portion of one or a plurality of the common electrodes <NUM> are formed on the inclined surface <NUM>.

As a specific example, the actuator <NUM> is formed of the stacked piezoelectric material in which two layers of piezoelectric materials are adhered to each other so that the polarization directions are opposite to each other. Herein, the piezoelectric material is, for example, PZT (lead zirconate titanate). The actuator <NUM> is adhered to the front surface <NUM> of the substrate <NUM> by, for example, thermosetting epoxy adhesive. The inclined surface <NUM> of the actuator <NUM> may be formed by, for example, cutting of the initially stacked layers of piezoelectric material. The substrate <NUM> and the actuator <NUM> the front surface <NUM> on which the plurality of individual electrodes <NUM> and the common electrode(s) <NUM> are formed is a polished surface. The grooves for forming the plurality of pressure chambers <NUM> and the plurality of air chambers <NUM> can be formed by cutting of the initially stacked layers of piezoelectric material.

In addition, a first electrode portion <NUM> and the second electrode portion <NUM>, which are each a portion of the plurality of individual electrodes <NUM>, and a first electrode portion <NUM> and the second electrode portion <NUM>, which are each a portion of a common electrode <NUM> are formed in the actuator <NUM>.

The pressure chambers <NUM> are deformed when the liquid ejection head <NUM> performs an operation such as printing, so that the ink is ejected from nozzles <NUM>. The pressure chamber <NUM> has an inlet connected to the first common liquid chamber <NUM> and an outlet connected to the second common liquid chamber <NUM>. The ink flows into the pressure chamber <NUM> from the inlet, and the ink flows out from the outlet. It is noted that, in other examples, the pressure chamber <NUM> may have a configuration where the ink flows in from both the openings described as the inlet and the outlet in the present example. The first electrode portions <NUM> are formed in the grooves constituting the pressure chambers <NUM>.

As illustrated in <FIG> and <FIG>, the air chamber <NUM> has an inlet side and an outlet side, but both are closed by a liquid-proof wall (resin wall) <NUM> formed of a photosensitive resin or the like, so that the air chamber <NUM> is separated (blocked) from the first common liquid chamber <NUM> and the second common liquid chamber <NUM>. The first electrode portion <NUM> as a portion of one or a plurality of the common electrodes <NUM> is formed in the air chamber <NUM>. As a specific example, the liquid-proof wall <NUM> of the air chamber <NUM> can be formed by injecting an ultraviolet curing resin onto the first electrode portion <NUM> in the groove forming the air chamber <NUM>, and after that, selectively irradiating the area using an exposure mask or the like with ultraviolet rays. The liquid-proof wall <NUM> prevents the ink from invading the air chamber <NUM>. In addition, the air chamber <NUM> is covered by the nozzle plate <NUM>, and a nozzle <NUM> is not arranged to connect to the air chamber <NUM>. Therefore, the ink can not flow into the air chamber <NUM>.

The nozzle plate <NUM> is fixed to the frame <NUM> opposite to the substrate <NUM> with adhesive or the like. The nozzle plate <NUM> has the plurality of nozzles <NUM> formed at positions facing the plurality of pressure chambers <NUM>. In the present embodiment, the nozzle plate <NUM> has two nozzle rows <NUM>.

The first common liquid chamber <NUM> is formed between the middle portions of the pair of actuators <NUM>, and constitutes an ink flow path from the supply port <NUM> to the primary side openings (inlets) of the pressure chambers <NUM> of each actuator <NUM>. The first common liquid chamber <NUM> extends along the longitudinal direction of the actuator <NUM>. The first common liquid chamber <NUM> constitutes a portion of an ink flow path which is also referred to as a second flow path.

The second common liquid chamber <NUM> is formed between an actuator <NUM> and the frame <NUM>. The second common liquid chamber <NUM> forms the ink flow path from the secondary side openings (outlets) of the pressure chambers <NUM> to a discharge port <NUM>. The second common liquid chamber <NUM> extends along the longitudinal direction of the actuator <NUM>. The second common liquid chamber <NUM> constitutes a portion of the ink flow path (second flow path).

The individual electrodes <NUM> individually apply drive voltages to the plurality of piezoelectric bodies <NUM>. The plurality of individual electrodes <NUM> can be used to selectively deform the respective pressure chambers <NUM>. The individual electrode <NUM> is formed by a wiring pattern portion formed on the substrate <NUM> and a wiring pattern portion formed on the actuator <NUM>. The plurality of individual electrodes <NUM> extend from the plurality of pressure chambers <NUM> along the lateral direction of the actuators <NUM> and are drawn out to a region of an outer side of the pair of actuators <NUM>.

As a specific example, as illustrated in <FIG> and <FIG>, the individual electrodes <NUM> are deposited on the inner surface of each pressure chamber <NUM>, the inclined surface <NUM> of an actuator <NUM>, and the substrate <NUM>. A portion of the individual electrode <NUM> formed on the inner surface of the pressure chamber <NUM> is formed on a side surface of the piezoelectric body <NUM> forming the pressure chamber <NUM> and a bottom surface of the groove forming the pressure chamber <NUM>. In addition, the individual electrodes <NUM> are formed on the inclined surface <NUM> and a portion of the front surface <NUM> of the substrate <NUM>. The individual electrodes <NUM> extend from the pressure chambers <NUM> to the edges of the substrate <NUM> in the lateral direction, and the ends of the individual electrodes <NUM> are arranged at the connection portions <NUM> to which the circuit board <NUM> of the substrate <NUM> is connected. That is, the individual electrode <NUM> includes the first electrode portion <NUM> formed in the groove constituting the pressure chamber <NUM> of the actuator <NUM>, the second electrode portion <NUM> formed on the inclined surface <NUM> of the actuator <NUM>, and the third electrode portion <NUM> formed on the front surface <NUM> of the substrate <NUM>. The individual electrode <NUM> is provided in close contact with the bottom surface of the groove forming the pressure chamber <NUM> and the side surface of the piezoelectric body <NUM> forming the pressure chamber <NUM>. The individual electrode <NUM> is formed by stacking, for example, a nickel (Ni) sputtered film <NUM>, an electroless Ni plated film <NUM>, and an electrolytic gold (Au) plated film <NUM>. The thickness of the individual electrode <NUM> is, for example, <NUM> to <NUM>.

Specifically, each of the first electrode portion <NUM>, the second electrode portion <NUM>, and the third electrode portion <NUM> is configured to have a three-layer stacked structure of a Ni sputtered film <NUM>, an electroless Ni plated film <NUM>, and an electrolytic Au plated film <NUM>. In some examples, the individual electrode <NUM> may lack the electrolytic Au plated film <NUM> in one or more portions. For example, the first electrode portion <NUM> may have a two-layer structure of a Ni sputtered film <NUM> and an electroless Ni plated film <NUM>.

The common electrode <NUM> is formed on both the main surfaces of the substrate <NUM>. The common electrode <NUM> applies the same drive voltage to all of the plurality of piezoelectric bodies <NUM>. The common electrode <NUM> is formed by a wiring pattern portion formed on the substrate <NUM> and a wiring pattern portion formed on the actuator <NUM>. The common electrode <NUM> is a wiring pattern provided from the inner peripheral surface of the supply port <NUM> of the substrate <NUM> to a piezoelectric body <NUM> forming the air chambers <NUM>. The common electrode <NUM> is connected to the circuit board <NUM>. The common electrode <NUM> is drawn out from the air chamber <NUM> to an area between the pair of actuators <NUM>. That is, the common electrode <NUM> is formed by connecting electrodes portions from the plurality of air chambers <NUM>.

As a specific example, the common electrode <NUM> is deposited on the inner surface of each air chamber <NUM>, the inclined surface <NUM> of the actuator <NUM>, the area avoiding the individual electrodes <NUM> on the front surface <NUM> of the substrate <NUM>, the back surface of the substrate <NUM>, and the inner surface of the supply port <NUM>. A portion of the common electrode <NUM> formed on the inner surface of each air chamber <NUM> is formed on a side surface of the piezoelectric body <NUM> forming each air chamber <NUM> and a bottom surface of the groove forming each air chamber <NUM>.

As a specific example, the common electrode <NUM> is provided on the inclined surface <NUM> from inside each air chamber <NUM> toward the central portion of the substrate <NUM> and on the front surface <NUM> of the substrate <NUM> between the pair of actuators <NUM> and the inner peripheral surface of the supply port <NUM>. In addition, the common electrode <NUM> is also formed on the back surface <NUM> of the substrate <NUM>. For example, the common electrode <NUM> extends to the edge of the substrate <NUM> in the lateral direction, and the end is arranged at the connection portion <NUM> to which the circuit board <NUM> of the substrate <NUM> is connected.

In other words, the common electrode <NUM> is provided between the pair of actuators <NUM> and extends to the connection portion <NUM> formed at an end of the substrate <NUM>. A portion of the common electrode <NUM> extends in the thickness direction of the substrate <NUM> on the inner peripheral surface of the supply port <NUM>. In addition, a portion of the common electrode <NUM> is provided on the front surface of the piezoelectric member forming each air chamber <NUM>. Furthermore, a portion of the common electrode <NUM> is provided on the back surface <NUM> of the substrate <NUM>.

That is, the common electrode <NUM> includes a plurality of first electrode portions <NUM> formed in the grooves constituting the air chambers <NUM> of the actuator <NUM>, at least one second electrode portion <NUM> formed on the inclined surface <NUM> of the actuator <NUM>, the third electrode portion <NUM> formed on the front surface <NUM> of the substrate <NUM>, the fourth electrode portion <NUM> formed on the inner peripheral (sidewall) surface of the supply port <NUM> and/or the discharge port <NUM>, and the fifth electrode portion <NUM> formed on the back surface <NUM> of the substrate <NUM>. The plurality of first electrode portions <NUM>, the second electrode portion(s) <NUM>, the third electrode portion <NUM>, the fourth electrode portion <NUM> and the fifth electrode portion <NUM> of the common electrode <NUM> are connected to each other. In some examples, the first electrode portion <NUM> may extend to the end in the longitudinal direction on the front surface <NUM> of the substrate <NUM>, and to the fourth electrode portion <NUM> or instead of just the fourth electrode portion <NUM>. An electrode portion may be formed on the longitudinal end surface of the substrate <NUM>, and the common electrode <NUM> may connect with the fifth electrode portion <NUM> on the back surface <NUM> through this electrode portion on the end surface of the substrate. Each of the electrode portions <NUM> to <NUM> of the common electrode <NUM> are formed avoiding the individual electrodes <NUM>. In addition, each of the electrode portions <NUM> to <NUM> of the common electrode <NUM> may be partially formed on the front surface of the substrate <NUM> or the actuator <NUM>.

For example, the fifth electrode portion <NUM> can be formed on the back surface of the substrate <NUM> at least at the position facing the opening (second liquid hole) of the first temperature control flow path <NUM> of the manifold <NUM> through which the temperature control fluid (second liquid) flows. The fifth electrode portion <NUM> may be formed on, for example, the entire back surface of the substrate <NUM>. It is noted that, as long as the fifth electrode portion <NUM> is connected with the third electrode portion <NUM> through the fourth electrode portion <NUM> or the like and is formed at the position facing at least the opening of the first temperature control flow path <NUM> on the back surface of the substrate <NUM>, the fifth electrode portion <NUM> may be formed on any portion of the back surface of the substrate <NUM>. It is noted that, from the viewpoint of securing the area of the common electrode <NUM>, it is preferable that the fifth electrode portion <NUM> of the common electrode <NUM> be formed over the entire back surface of the substrate <NUM> or over as wide a range of the back surface of the substrate <NUM> as feasible in view of any other constraints.

In the common electrode <NUM>, the third electrode portion <NUM> on the front surface <NUM> and the fifth electrode portion <NUM> on the back surface <NUM> are connected by the fourth electrode portion <NUM> inside the supply port <NUM>. It is noted that the common electrode <NUM> may extend to the ends (edges) of the front surface <NUM> of the substrate <NUM> in the longitudinal direction and continue to the back surface at the end surfaces of the substrate <NUM> in the longitudinal direction.

The common electrode <NUM> is provided so as to be in close contact with the bottom of the air chamber <NUM> and the front surface of the piezoelectric member forming the piezoelectric body <NUM>. The common electrode <NUM> can have a multi-layer structure where, for example, a Ni sputtered film <NUM>, an electroless Ni plated film <NUM>, and an electrolytic Au plated film <NUM> are stacked. For example, the electrode film constituting the common electrode <NUM> has a three-layer stacked structure of the Ni sputtered film <NUM>, the electroless Ni plated film <NUM>, and the electrolytic Au plated film <NUM> on the front side and a two-layer stacked structure of the Ni sputtered film <NUM> and the electrolytic Au plated film <NUM>.

For example, each of the first electrode portion <NUM>, the second electrode portion <NUM>, and the third electrode portion <NUM> may have a three-layer stacked structure of a Ni sputtered film <NUM>, an electroless Ni plated film <NUM>, and an electrolytic Au plated film <NUM>. In some examples, the first electrode portion <NUM> inside the groove may have just a two-layer structure of a Ni sputtered film <NUM> and an electroless Ni plated film <NUM>.

Each of the fourth electrode portion <NUM> and the fifth electrode portion <NUM> may have a two-layer stacked structure of a Ni sputtered film <NUM> and an electrolytic Au plated film <NUM>. In addition, similarly to the first electrode portion <NUM>, the second electrode portion <NUM>, and the third electrode portion <NUM>, the fourth electrode portion <NUM> and the fifth electrode portion <NUM> may have a three-layer stacked structure of a Ni sputtered film <NUM>, an electroless Ni plated film <NUM>, and an electrolytic Au plated film <NUM>.

The thickness of the common electrode <NUM> is, for example, <NUM> to <NUM>. It is noted that the thickness of the common electrode <NUM> is generally configured to be larger than the thickness of the individual electrodes <NUM>. The common electrode <NUM> is typically configured to have lower resistance per unit length or the like than the individual electrodes <NUM>. In other words, the thickness of the individual electrodes <NUM> is usually less than the thickness of the common electrode <NUM>. The individual electrode <NUM> may have a higher resistance value per unit length or the like than the common electrode <NUM>.

As illustrated in <FIG>, <FIG>, <FIG>, and <FIG>, the manifold unit <NUM> includes the manifold <NUM>, a top plate <NUM>, an ink supply tube <NUM>, an ink discharge tube <NUM>, a first temperature control fluid supply tube <NUM>, a first temperature control fluid discharge tube <NUM>, and a shielding member <NUM>. It is noted that the number of the ink supply tubes <NUM>, the ink discharge tubes <NUM>, the first temperature control fluid supply tubes <NUM>, and the first temperature control fluid discharge tubes <NUM> can be appropriately varied.

The manifold <NUM> is formed in a plate shape or a block shape. The manifold <NUM> includes a supply flow path <NUM> that connects with the supply port <NUM> of the substrate <NUM> and forms a liquid supply flow path (which is a portion of the second flow path), a discharge flow path <NUM> that connects with the discharge port <NUM> of the substrate <NUM> and forms the liquid discharge flow path (that is a portion of the second flow path). The manifold <NUM> also includes a first temperature control flow path <NUM> that forms part of the flow path of temperature control fluid. It is noted that, since the manifold <NUM> is connected to a pair of head bodies <NUM>, the manifold <NUM> has a pair of supply flow paths <NUM> and a pair of discharge flow paths <NUM>.

The manifold <NUM> is formed, for example, by assembling a plurality of manifold members to form the supply flow path <NUM>, the discharge flow path <NUM>, and the first temperature control flow path <NUM>.

One main surface of the manifold <NUM> is fixed to the back surface <NUM> of the substrate <NUM> through the shielding member <NUM>. In addition, the top plate <NUM> is fixed to the manifold <NUM> opposite to the substrate <NUM>. The ink supply tube <NUM>, the ink discharge tube <NUM>, the first temperature control fluid supply tube <NUM> and the first temperature control fluid discharge tube <NUM> are fixed to the manifold <NUM> through the top plate <NUM>.

The supply flow path <NUM> is formed in the manifold <NUM> by holes and grooves. The supply flow path <NUM> includes a hole (first liquid hole) that opens to the main surface of the manifold <NUM> facing the substrate <NUM>. For example, the supply flow path <NUM> is a cuboidal liquid chamber extending along the longitudinal direction of the actuator <NUM> and the longitudinal direction of the supply port <NUM>. The supply flow path <NUM> fluidly connects the ink supply tube <NUM> and the supply port <NUM> of the substrate <NUM>.

The discharge flow path <NUM> is formed in the manifold <NUM> by holes and grooves. The discharge flow path <NUM> includes a hole (first liquid hole) that opens to the main surface of the manifold <NUM> facing the substrate <NUM>. The discharge flow path <NUM> fluidly connects the ink discharge tube <NUM> and the discharge port <NUM> of the substrate <NUM>.

The first temperature control flow path <NUM> is formed in the manifold <NUM> by holes or grooves. The first temperature control flow path <NUM> has a groove formed in the surface of the manifold <NUM> facing the substrate <NUM>, and the opening of the groove is covered with the shielding member <NUM>. As the example, the first temperature control flow path <NUM> is formed with one opening (second liquid hole) <NUM> for each actuator <NUM>. For example, the two openings <NUM> of the first temperature control flow path <NUM> are arranged on the side of the actuator <NUM> on the discharge side of the pressure chamber <NUM> and extend along the longitudinal direction of the actuator <NUM>. For example, the two openings <NUM> of the first temperature control flow path <NUM> are formed at the respective positions facing the back surface <NUM> of the substrate <NUM> on the side surface side of the substrate <NUM> in the lateral direction (Y direction) from the central side of the substrate <NUM> where the supply port <NUM> is formed. The first temperature control flow path <NUM> fluidly connects the temperature control fluid supply tube <NUM> and the temperature control fluid discharge tube <NUM>.

The ends of the first temperature control flow path <NUM> are openings connected to the temperature control fluid supply tube <NUM> and the temperature control fluid discharge tube <NUM> provided on the surface of the manifold <NUM>. In addition, the first temperature control flow path <NUM> is formed so as to be able to exchange heat through the shielding member <NUM> with the substrate <NUM> fixed to the manifold <NUM>. The temperature control fluid flows through the first temperature control flow path <NUM> to promote heat exchange.

The top plate <NUM> is provided on the surface of the manifold <NUM> opposite to the surface on which the substrate <NUM> is provided. In addition, the top plate <NUM> also has openings that connect the tubes <NUM>, <NUM>, and <NUM> and allow the tubes <NUM>, <NUM>, and <NUM> and the flow paths <NUM> and <NUM> to connect with each other.

The ink supply tube <NUM> is connected to the supply flow path <NUM>. The ink discharge tube <NUM> is connected to the discharge flow path. The temperature control fluid supply tube <NUM> and the temperature control fluid discharge tube <NUM> are connected to the primary side and the secondary side of the first temperature control flow path <NUM>.

In the present embodiment, the pair of ink supply tubes <NUM> and the first temperature control fluid discharge tube <NUM> are arranged on one end side of the manifold <NUM> in the longitudinal direction, and the pair of ink discharge tubes <NUM> and the first temperature control fluid supply tube <NUM> are arranged on the other end side of the manifold <NUM> in the longitudinal direction. It is noted that the arrangement and number of the ink supply tube <NUM>, the ink discharge tube <NUM>, the first temperature control fluid supply tube <NUM>, and the first temperature control fluid discharge tube <NUM> are not limited to this example.

The shielding member <NUM> covers at least the two openings <NUM> of the first temperature control flow path <NUM> formed on the surface of the manifold <NUM> facing the substrate <NUM>. The shielding member <NUM> covers the two openings <NUM> to prevent the temperature control fluid flowing through the first temperature control flow path <NUM> from being in contact with the common electrode <NUM> on the substrate <NUM>. The shielding member <NUM> is made of a material that is corrosion resistant with respect to the temperature control fluid. The shielding member <NUM> is formed in a film shape or a sheet shape.

One shielding member <NUM> or, alternatively, the same number of the shielding members <NUM> as the number of the openings <NUM> formed in the main surface of the manifold <NUM> of the first temperature control flow path <NUM> can be provided. If just one shielding member <NUM> is provided, this shielding member <NUM> can be provided on a partial area including the two openings <NUM> on the surface of the manifold <NUM> or over the entire area of the surface of the manifold <NUM>. It is noted that, if separate shielding members <NUM> are provided for each of the openings <NUM>, each shielding members <NUM> may respectively cover one of the openings <NUM>, respectively.

In a specific example illustrated in <FIG>, a single shielding member <NUM> is provided, and the shielding member <NUM> covers the two openings <NUM> and no through-holes are formed in the regions facing the two openings <NUM>. The shielding member <NUM> is formed, in this example, in the same shape as the outer edge shape of the surface of the manifold <NUM> facing the substrate <NUM> or the outer edge shape of the back surface <NUM> of the substrate <NUM> and covers the region of the surface of the manifold <NUM> facing the electrode portion <NUM>.

A first through-hole <NUM> and a second through-hole <NUM> are formed in the shielding member <NUM>. The first through-hole <NUM> allows the supply port <NUM> of the substrate <NUM> and the supply flow path <NUM> formed in the manifold <NUM> to communicate with each other. The first through-hole <NUM> is formed in a region of the shielding member <NUM> facing the supply port <NUM> and the supply flow path <NUM>. The first through-hole <NUM> is, for example, an elongated hole formed in the same shape as the opening of the supply port <NUM> and/or the opening of the supply flow path <NUM>.

The second through-hole <NUM> allows the discharge port <NUM> of the substrate <NUM> and the discharge flow path <NUM> formed in the manifold <NUM> to communicate with each other. The second through-hole <NUM> is formed in a region of the shielding member <NUM> facing the discharge port <NUM> and the discharge flow path <NUM>. For example, one second through-hole <NUM> is formed on one end of the shielding member <NUM> in the longitudinal direction (X direction) and is an elongated hole extending in the lateral direction (Y direction), facing the two discharge ports <NUM> formed on one end side of the substrate <NUM> in the longitudinal direction (X direction) of the four discharge ports <NUM> formed in the substrate <NUM>. In this example, the two discharge ports <NUM> that do not face the second through-holes <NUM> are covered and blocked by the shielding member <NUM>.

It is noted that the second through-holes <NUM> may be at both ends of the shielding member <NUM> in some examples. In addition, the second through-hole <NUM> may in the same shape as the discharge port <NUM> instead of being an elongated hole, and second through-holes <NUM> may be formed to face the respective discharge ports <NUM>.

The shielding member <NUM> is attached to the substrate <NUM> and the manifold <NUM> with adhesive, for example. The shielding member <NUM> can be made of a material having a linear expansion coefficient close to that of the substrate <NUM> and the manifold <NUM> material. As a specific example, a difference between the linear expansion coefficient of the shielding member <NUM> and the linear expansion coefficient of the substrate <NUM> and a difference between the linear expansion coefficient of the shielding member <NUM> and the linear expansion coefficient of the manifold <NUM> can be <NUM> x <NUM>-<NUM> (/K) or less.

The shielding member <NUM> can be made of a material with a high thermal conductivity, for example, a material with a thermal conductivity of <NUM> W/(m·K) or more. In addition, the shielding member <NUM> can be made of, for example, a non-conductive material.

As a specific example, the shielding member <NUM> is made of a polyimide film. From the viewpoint of thermal conduction, the polyimide film forming the shielding member <NUM> preferably has a thermal conductivity of <NUM> W/(m·K) or more and a thickness of <NUM> or less.

It is noted that the shielding member <NUM> may be made of other materials besides a polyimide film. For example, if the substrate <NUM> and the manifold <NUM> are made of ceramics, a configuration may be used where, shielding member <NUM> is made of ceramics so the linear expansion coefficients are close to each other. From the viewpoint of thermal conduction, it is preferable that the ceramic material forming the shielding member <NUM> has a thermal conductivity of <NUM> W/(m·K) or more and a thickness of <NUM> or less.

As a specific example, if the substrate <NUM> and the manifold <NUM> are alumina and the shielding member <NUM> is a polyimide film, a difference between the linear expansion coefficient of the shielding member <NUM> and the linear expansion coefficient of the substrate <NUM> and a difference between the linear expansion coefficient of the shielding member <NUM> and the linear expansion coefficient of the manifold <NUM> is <NUM> x <NUM>-<NUM> (/K) or less. In addition, if the substrate <NUM> and the manifold <NUM> are made of alumina and the shielding member <NUM> can be made of ceramics as well, a difference between the linear expansion coefficient of the shielding member <NUM> and the linear expansion coefficient of the substrate <NUM> and a difference between the linear expansion coefficient of the shielding member <NUM> and the linear expansion coefficient of the manifold <NUM> is <NUM> x <NUM>-<NUM> (/K) or less. The shielding member <NUM> can be alumina.

It is noted that these described materials of the shielding member <NUM> are merely non-limiting examples. However, from the viewpoint of adhesion, it is preferable that the differences between the linear expansion coefficients of the substrate <NUM> and the manifold <NUM> and the linear expansion coefficient of the shielding member <NUM> are preferably set within the above-mentioned range, and it is preferable that, from the viewpoint of temperature control, a heat transfer coefficient and a thickness of the shielding member <NUM> are within a numerical range in which heat can be effectively transferred between the temperature control fluid and the substrate <NUM>.

The temperature control flow path unit <NUM> has a plurality of second temperature control flow paths <NUM>, a second temperature control fluid supply tube <NUM>, and a second temperature control fluid discharge tube <NUM>. A plurality of openings <NUM> are formed between the plurality of second temperature control flow paths <NUM> in the temperature control flow path unit <NUM>. The temperature control flow path unit <NUM> is connected to the temperature control device <NUM> of the liquid ejection apparatus <NUM>. The second temperature control flow paths <NUM> are long in the X direction and arranged in the Y direction perpendicular to the second temperature control flow paths <NUM>.

As a specific example, since the pair of head bodies <NUM> are provided in the present embodiment, four nozzle rows <NUM>, four actuators <NUM>, and four driver ICs <NUM> are provided. With this arrangement, the temperature control flow path unit <NUM> has three second temperature control flow paths <NUM>, and two openings <NUM> are formed between the second temperature control flow paths <NUM>.

The plurality of second temperature control flow paths <NUM> are connected to the second temperature control fluid supply tube <NUM> and the second temperature control fluid discharge tube <NUM>.

In the temperature control flow path unit <NUM>, a portion of the driver IC <NUM> of the circuit board <NUM> and a printed wiring board <NUM> are arranged in the openings <NUM>, and the plurality of second temperature control flow paths <NUM> are arranged to face the driver IC <NUM> (which acts in this context as a heating element), so that cooling of the driver IC <NUM> is performed.

As illustrated in <FIG> and <FIG>, the circuit board <NUM> includes the driver IC <NUM> of which is connected to the connection portion <NUM> of the substrate <NUM> and the printed wiring board <NUM>.

The circuit board <NUM> drives the actuator <NUM> by applying a drive voltage to the wiring pattern for the actuator <NUM> from the driver IC <NUM>. The applied voltage increases or decreases the volume of the pressure chamber <NUM>, and acts to eject liquid droplets from the nozzle <NUM>.

The driver IC <NUM> is connected to the plurality of individual electrodes <NUM> and the common electrode <NUM> through the ACF (anisotropic conductive film) fixed to the connection portion of the substrate <NUM> by thermocompression. The driver IC <NUM> generates heat during operation. It is noted that the driver IC <NUM> may be connected to the plurality of individual electrodes <NUM> and the common electrode <NUM> by other means such as ACP (anisotropic conductive paste), NCF (non-conductive film), and NCP (non-conductive paste). The plurality of driver ICs <NUM> to be connected are provided, for example, for each head body <NUM>. In the present embodiment, driver ICs <NUM> are connected to each actuator <NUM>. The driver IC <NUM> is, for example, a COF (chip on film) in which an IC chip is mounted on a film. The front surface of the driver IC <NUM> is in contact with the outer surface of the second temperature control flow path <NUM>.

The printed wiring board <NUM> is a PWA (printing wiring assembly) on which various electronic components and connectors are mounted.

The cover <NUM> includes, for example, an outer shell <NUM> covering the side surfaces of the pair of head bodies <NUM>, the manifold unit <NUM>, and the circuit board <NUM> and a mask plate covering a portion of the pair of head bodies <NUM> on the nozzle plate <NUM> side.

The outer shell <NUM> exposes, for example, the ink supply tube <NUM>, the ink discharge tube <NUM>, the temperature control fluid supply tube <NUM>, and the temperature control fluid discharge tube of the manifold unit <NUM> and the end of the circuit board <NUM> to the outside.

The mask plate covers the pair of head bodies <NUM> except for the nozzles <NUM> and the nozzle plate <NUM> surrounding the nozzles <NUM>.

The liquid ejection head <NUM> has a plurality of individual electrodes <NUM> for individually applying a drive voltage to each of the piezoelectric bodies <NUM> and a common electrode <NUM> capable of applying a drive voltage to all the piezoelectric bodies <NUM> in the head body <NUM>.

The liquid ejection head <NUM> can drive the plurality of pressure chambers <NUM> selectively in groups, individually, or collectively (all simultaneously). When a pressure chamber <NUM> is driven, the pressure chamber <NUM> is deformed in a shear-mode, and thus, the ink in the pressure chamber <NUM> is pressurized (compressed). Therefore, the liquid ejection head <NUM> can selectively eject the ink from the nozzles <NUM> facing the pressure chambers <NUM>.

The common electrode <NUM> is also formed on the front surface <NUM> of the actuator <NUM>, the inclined surface <NUM> of the actuator <NUM>, the inner surface of the air chamber <NUM>, and the inner peripheral surface of the supply port <NUM> formed in the substrate <NUM>.

The liquid ejection head <NUM> has the first temperature control flow path <NUM> for controlling the temperature of the head body <NUM> and the second temperature control flow path <NUM> for cooling the driver IC <NUM> using the manifold unit <NUM> and the temperature control flow path unit <NUM>. The temperature control fluid supplied from the second temperature control fluid supply tube <NUM> is discharged from the second temperature control fluid discharge tube <NUM> through the first temperature control flow path <NUM> and the second temperature control flow path <NUM>. The temperature control fluid flowing through the first temperature control flow path <NUM> cools the substrate <NUM> through the shielding member <NUM> for controlling the temperature of the head body <NUM>, and the temperature control fluid flowing through the second temperature control flow path <NUM> cools the driver IC <NUM>.

A liquid ejection apparatus <NUM> incorporating a liquid ejection head <NUM> will be described with reference to <FIG>. The liquid ejection apparatus <NUM> includes a housing <NUM>, a medium supply unit <NUM>, an image formation unit <NUM>, a medium discharge unit <NUM>, a conveying device <NUM> as a media support, a maintenance device <NUM>, and a control unit <NUM>. The liquid ejection apparatus <NUM> also includes a temperature control device that controls the temperature of the ink supplied to the liquid ejection head <NUM>.

The liquid ejection apparatus <NUM> can be an inkjet printer that performs an image forming process on paper P by ejecting a liquid such as ink while conveying a recording medium to be ejected, for example, the paper P, along a predetermined conveyance path <NUM> from the medium supply unit <NUM> to the medium discharge unit <NUM> through the image formation unit <NUM>.

The medium supply unit <NUM> has a plurality of paper feed cassettes <NUM>. The image formation unit <NUM> includes a support unit <NUM> that supports the paper and a plurality of head units <NUM> above the support unit <NUM>. The medium discharge unit <NUM> includes a paper discharge tray <NUM>.

The support unit <NUM> includes a conveying belt <NUM> provided in a loop shape, a support plate <NUM> supporting the conveying belt <NUM> from the back side, and a plurality of belt rollers <NUM> provided on the back side of the conveying belt <NUM>.

The head unit <NUM> includes a plurality of liquid ejection heads <NUM>, a plurality of supply tanks <NUM> mounted on the respective liquid ejection heads <NUM>, a pump <NUM> that supplies the ink, and a connection flow path <NUM> that connects the liquid ejection heads <NUM> to the supply tanks <NUM>.

In the present embodiment, the liquid ejection heads <NUM> are provided for four colors, cyan, magenta, yellow, and black along with four supply tanks <NUM> containing the ink of respective colors. A supply tank <NUM> is connected to a liquid ejection head <NUM> by a connection flow path <NUM>.

The pump <NUM> is, for example, a liquid feed pump such as a piezoelectric pump. The pump <NUM> is connected to the control unit <NUM> and driven and controlled by the control unit <NUM>.

The connection flow path <NUM> has a supply flow path connected to the ink supply tube <NUM> of the liquid ejection head <NUM>. In addition, the connection flow path <NUM> includes a recovery flow path connected to the ink discharge tube <NUM> of the liquid ejection head <NUM>. For example, if the liquid ejection head <NUM> is of the non-circulating type, a recovery circuit is connected to a maintenance device <NUM>, and if the liquid ejection head <NUM> is of the circulating type, the recovery flow path is connected to the supply tank <NUM>.

The conveying device <NUM> conveys the paper P along the conveyance path <NUM> from the paper feed cassette <NUM> to the paper discharge tray <NUM> through the image formation unit <NUM>. The conveying device <NUM> includes a plurality of guide plate pairs <NUM> to <NUM> arranged along the conveyance path <NUM> and a plurality of conveying rollers <NUM> to <NUM>. The conveying device <NUM> supports the paper P and moves the paper P relative to the liquid ejection head <NUM>.

The temperature control device <NUM> has the temperature control fluid tank <NUM>, the temperature control circuit <NUM> (in this context, the "circuit" comprises components such as pipes and tubes) for supplying the temperature control fluid, the pump for supplying the temperature control fluid, the cooler and/or the heater for controlling the temperature of the temperature control fluid, and the like. The temperature control device <NUM> supplies the temperature control fluid from the temperature control fluid tank <NUM> at a predetermined temperature by using the cooler, the heater, or the like to the second temperature control fluid supply tube <NUM> through the temperature control circuit <NUM> using the pump. In addition, the temperature control device <NUM> recovers the temperature control fluid discharged from the second temperature control fluid discharge tube <NUM> through the first temperature control flow path <NUM> and the second temperature control flow path <NUM> into the temperature control fluid tank <NUM> through the temperature control circuit <NUM>.

The maintenance device <NUM>, for example, suctions and recovers the ink remaining on the outer surface of the nozzle plate <NUM> during a maintenance operation. In addition, if the liquid ejection head <NUM> is of the non-circulating type, the maintenance device <NUM> recovers the ink from inside the head body <NUM> during a maintenance operation. The maintenance device <NUM> has a tray, a tank, or the like for storing the recovered ink.

The control unit <NUM> includes a CPU <NUM> (as an example of a processor), a memory such as a ROM (read only memory) for storing various programs, and a RAM (random access memory) for temporarily storing various variable data and image data, and an interface unit for receiving data (input) from the outside and outputting data to the outside.

In the liquid ejection head <NUM> and the liquid ejection apparatus <NUM>, the opening <NUM> of the first temperature control flow path <NUM> formed on the surface of the manifold <NUM> facing the back surface <NUM> of the substrate <NUM> is covered with the shielding member <NUM>. In addition, the common electrode <NUM> formed at the position facing the opening <NUM> of the first temperature control flow path <NUM> is covered with the shielding member <NUM>. Therefore, since the common electrode <NUM> is not in contact with the temperature control fluid, the liquid ejection head <NUM> can avoid corrosion of the common electrode <NUM> while still maintaining the cooling performance of the temperature control fluid. Therefore, the liquid ejection head <NUM> can prevent the common electrode <NUM> from being corroded by electrolysis during operation of the liquid ejection head <NUM> with the temperature control fluid in contact with the common electrode <NUM> and can prevent the resistance of the common electrode <NUM> from increasing due to corrosion. Thus, the liquid ejection head <NUM> can prevent the driver IC <NUM> from being damaged due to latch-up or the like. In addition, the liquid ejection head <NUM> can avoid differences in a drive waveform from being applied to the end portions and the center portion of the actuator row and can maintain good printing quality such as dot diameter and linearity.

The shielding member <NUM> may avoid peel off from the substrate <NUM> and the manifold <NUM> when the difference in the linear expansion coefficient between shielding member <NUM> and the substrate <NUM> and the manifold <NUM> is within the above-described ranges.

In addition, the shielding member <NUM> can have the same shape as the outer edge shape of the main surface of the manifold <NUM> facing the substrate <NUM> or the outer edge shape of the back surface <NUM> of the substrate <NUM>, so that the shielding member <NUM> can cover two openings of the first temperature control flow path <NUM> formed in the main surface of the manifold <NUM>. In addition, the shielding member <NUM> has the same shape as the outer edge shape of the main surface of the manifold <NUM> facing the substrate <NUM> or the outer edge shape of the back surface <NUM> of the substrate <NUM>, so that the shielding member <NUM> can easily perform position alignment when being attached to the substrate <NUM> and the manifold <NUM>. Therefore, the liquid ejection head <NUM> can be produced without additional manufacturing difficult.

In an embodiment, in the liquid ejection head <NUM> and the liquid ejection apparatus <NUM>, corrosion of the common electrode <NUM> can be prevented by covering the opening of the first temperature control flow path <NUM> (through which the temperature control fluid flows) and the common electrode <NUM> facing the opening of the first temperature control flow path <NUM> with the shielding member <NUM>.

It is noted that the embodiments of the present disclosure are not limited to the specific configurations described above. In an example, a single shielding member <NUM> is provided that has the same shape as the outer edge shape of the main surface of the manifold <NUM> facing the substrate <NUM> or the outer edge shape of the back surface <NUM> of the substrate <NUM>, but the present disclosure is not limited thereto. For example, even in a case where one shielding member <NUM> is used, if all the openings <NUM> can still be covered, the shape of the shielding member <NUM> may be different from the outer edge shape of the main surface of the manifold <NUM> facing the substrate <NUM> or the outer edge shape of the back surface <NUM> of the substrate <NUM>. In addition, multiple shielding members <NUM> may be used to cover the openings of the first temperature control flow paths <NUM> formed on the main surface of the manifold <NUM>, and each of these shielding members <NUM> may separately cover one or a subset of the openings of the first temperature control flow paths <NUM>. In another example, the number of openings <NUM> may be provided to face a portion of the common electrode <NUM> can be varied as appropriate.

Although an example is described where the shielding member <NUM> prevents the temperature control fluid from contacting the common electrode <NUM>, the present disclosure is not limited thereto. That is, the liquid blocked by the shielding member <NUM> may be any liquid that might corrode the common electrode <NUM>. It is noted that preferably the material forming the shielding member <NUM> is a material that is corrosion resistant with respect to the liquid to be shielded.

That is, in a case where the shielding member <NUM> is configured to cover a portion of the common electrode <NUM> and the opening of the flow path of the liquid corroding the common electrode <NUM> if the common electrode <NUM> is in contact with the liquid, the shape and number of the shielding member <NUM>, the common electrode <NUM>, and the openings (for example, the openings <NUM> of the first temperature control flow path <NUM>) of the flow path of the liquid can be set as appropriate.

In an example, the supply port <NUM> is an elongated hole is arranged between the pair of actuators <NUM> and the discharge port <NUM> is arranged at both ends of the pair of actuators <NUM> in the longitudinal direction, but in other examples, the shape, number, and arrangement of the supply port <NUM> and the discharge port <NUM> can be varied as appropriate.

In an example, the common electrode <NUM> a portion of the common electrode <NUM> may be formed on the inner wall of the discharge port <NUM> in addition to the fourth electrode portion <NUM> formed in the supply port <NUM> or even instead of the fourth electrode portion <NUM>. In addition, a portion of the common electrode <NUM> may be formed on the end surface of the substrate <NUM>. Furthermore, the substrate <NUM> may be formed with a through-hole for a portion of the common electrode <NUM> to be formed on the inner surface thereof. For example, the area of the common electrode <NUM> can be increased by the electrode film being formed on the discharge port <NUM>, the end surface, and/or a through-hole, and the resistance value can be further reduced. However, if a portion of the common electrode <NUM> faces the flow path through which a corroding liquid (second liquid) flows, the shielding member <NUM> can be configured to cover the flow path and the common electrode <NUM> facing the flow path.

In an example, the individual electrode <NUM> is formed in the pressure chamber <NUM> and the common electrode <NUM> is formed in the air chamber <NUM>, but, in other examples, the common electrode <NUM> may be formed in the pressure chamber <NUM>, and the individual electrode <NUM> may be formed in the air chamber <NUM>.

In an example, liquid ejection head <NUM> is an independently-driven type head and, among the common electrodes <NUM> that are the electrode portions formed over the front and back main surfaces of the substrate <NUM>, the common electrode <NUM> on the back surface of the substrate <NUM> is covered with the shielding member <NUM>, but the present disclosure is not limited thereto. For example, a configuration may be adopted in which some electrode other than the common electrode is provided on a part of the back surface <NUM> of the substrate <NUM> and this other electrode may be covered with the shielding member <NUM>. That is, the liquid ejection head <NUM> can prevent corrosion of any electrode type by covering the relevant electrode portion provided on the back surface <NUM> of the substrate <NUM> with the shielding member <NUM>. With such a configuration, for example, even if the liquid ejection head <NUM> is a division-driving type head, corrosion of the electrode provided on the back surface <NUM> of the substrate <NUM> can be prevented.

In an example, the liquid ejection head <NUM> is provided with a pair of head bodies <NUM>, but a configuration having one head body <NUM> may instead be adopted in other examples. Furthermore, although a configuration is described where the head body <NUM> has a pair of actuators <NUM>, a configuration where the head body <NUM> has just one actuator <NUM> may be adopted in other examples.

The liquid ejection head <NUM> can be of a non-circulating type or of a circulating type.

In an example, an inkjet head <NUM> in which one side of the pressure chamber <NUM> is the supply side, the other side is the discharge side, and the ink flows in from one side of the pressure chamber <NUM> and flows out from the other side is exemplified, but the present disclosure is not limited thereto. In other examples, common chambers on both sides of the pressure chamber <NUM> can function as the supply side and the ink inflows from both sides may be adopted. In addition, the supply side and the discharge side may be reversed or may be configured to be switchable in other examples.

In an example, a side shooter type inkjet head is exemplified, but the present disclosure is not limited to this, and an end-shooter type inkjet head may be used in other examples.

In The liquid to be ejected is not limited to printing ink, and a device for ejecting liquid containing conductive particles for forming a wiring pattern of a printed wiring board may be provided according to the present disclosure.

In an example, the inkjet head <NUM> is used in the liquid ejection apparatus <NUM> such as an inkjet printer, the present disclosure is not limited thereto and the inkjet head <NUM> or the like can also be used in, for example, 3D printers, industrial manufacturing machines, and medical applications and can reduce the size, weight, and cost of such devices.

According to at least one of the embodiments described above, the flow path through which a potentially corrosive liquid flows can be prevented from contacting an electrode element (e.g., the common electrode) otherwise exposed to the corrosive liquid flow path by being covered with a shielding member, so that corrosion of the electrode can be prevented.

Claim 1:
A liquid ejection head (<NUM>), comprising:
a substrate (<NUM>) with a hole (<NUM>);
a nozzle plate (<NUM>) with a plurality of nozzles;
an actuator (<NUM>) on a first surface of the substrate (<NUM>), the actuator having a plurality of pressure chambers (<NUM>) aligned to the plurality of nozzles;
an electrode (<NUM>) having a first portion on the first surface of the substrate (<NUM>) and a second portion on a second surface of the substrate (<NUM>), the second surface being on an opposite side of the substrate (<NUM>) from the first surface;
a manifold (<NUM>) with a first liquid hole (<NUM>) facing the hole in the substrate (<NUM>), wherein the manifold includes a first liquid flow path for a first liquid, the first liquid flow path connected to the first liquid hole,
wherein the manifold further includes a second liquid hole (<NUM>) facing another portion of the substrate (<NUM>) other than the hole; and
a second liquid flow path (<NUM>) for a second liquid different from the first liquid, the second liquid being a temperature control fluid for controlling temperature in the liquid ejection head and/or the first liquid, the second liquid flow path being connected to the second liquid hole, wherein the liquid ejection head further comprises a shielding member (<NUM>) between the substrate (<NUM>) and the manifold (<NUM>) and covering the second liquid hole.