Patent Description:
There is known an inkjet head including a nozzle layer having a nozzle and a liquid chamber substrate having a liquid chamber. In such an inkjet head, a piezoelectric actuator is disposed in the nozzle layer. In the above-described inkjet head, the piezoelectric actuator is disposed adjacent to the nozzle to discharge ink, and a drive circuit is disposed in the liquid chamber substrate to drive the piezoelectric actuator. In this case, a circuit connection is provided to supply power to the drive circuit.

In PTL <NUM>, the piezoelectric actuator is disposed in at least a part of a nozzle portion of the nozzle layer and over a side of the nozzle layer from which liquid is discharged. A bonding pad (also referred to as the circuit connection) is disposed over the side of the nozzle layer from which the liquid is discharged to energize the drive circuit that drives the piezoelectric actuator. Further, a protective layer is disposed on the side of the nozzle layer from which the liquid is discharged to protect the piezoelectric actuator. The protective layer is opened at portions of the nozzle and the bonding pad. <CIT> discloses a plurality of pressure chambers that are provided on a substrate, and a piezoelectric actuator and an ink ejection nozzle that are provided thereon through a diaphragm.

The protective layer includes, for example, a polyimide-based resin that has high hygroscopicity. If moisture is absorbed (enters) through the protective layer having high hygroscopicity into the piezoelectric actuator below the protective layer, the piezoelectric actuator may deteriorate in performance. Therefore, a water-resistant film is generally formed over the protective layer. In a manufacturing process of the inkjet head as a comparative technique, a piezoelectric actuator, an electrode pad (bonding pad), a protective layer, a water-resistant film, and a pad opening that exposes the electrode pad are generally formed in this order. Accordingly, the water-resistant film is not present on the side surface of the protective layer facing the pad opening. As a result, in the comparative technique, moisture is absorbed from the pad opening above the bonding pad (circuit connection), and the piezoelectric actuator may deteriorate in performance. If moisture in the outside air is absorbed from the pad opening above the circuit connection, the moisture may erode the piezoelectric actuator, and the piezoelectric actuator may deteriorate. The moisture absorption may shorten the life of the inkjet head and may decrease the reliability of the inkjet head.

As described above, in a liquid discharge head including a nozzle layer in which a piezoelectric actuator and a circuit connection are disposed, moisture absorption from an opening above the circuit connection may cause the piezoelectric actuator to deteriorate. To solve such a situation, the present disclosure has an object to provide a liquid discharge head that can prevent the piezoelectric actuator from deteriorating in the piezoelectric performance.

A liquid discharge head includes a nozzle layer having a nozzle through which a liquid is discharged, a liquid chamber substrate, and a drive circuit. The nozzle layer includes a vibration layer having a first side and a second side opposite to the first side, a piezoelectric actuator adjacent to the nozzle and over the first side, a circuit connection over the first side, a first protective layer around the circuit connection, a second protective layer over the piezoelectric actuator, a first water-resistant film over a surface of the first protective layer, and a second water-resistant film over a surface of the second protective layer. The liquid is discharged through the nozzle in a direction from the second side toward the first side. The second protective layer is separated from the first protective layer. The first protective layer defines an opening above the circuit connection. The liquid chamber substrate has a liquid chamber communicating with the nozzle. The drive circuit is disposed over the second side and connected to the circuit connection to drive the piezoelectric actuator.

According to the present disclosure, the liquid discharge head can be provided that includes the nozzle layer in which the piezoelectric actuator and the circuit connection are disposed and prevents the deterioration of piezoelectric performance of the piezoelectric actuator due to the moisture absorption from the opening above the circuit connection.

Hereinafter, a liquid discharge head, a liquid discharge device, and a liquid discharge apparatus according to embodiments of the present disclosure is described with reference to the drawings. It is to be noted that the following embodiments are not limiting the present disclosure and any deletion, addition, modification, change, etc. can be made within a scope in which person skilled in the art can conceive including other embodiments, and any of which is included within the scope of the present disclosure as long as the effect and feature of the present disclosure are exhibited.

A liquid discharge head according the present disclosure includes a nozzle layer having a nozzle through which a liquid is discharged, a liquid chamber substrate, and a drive circuit. The nozzle layer includes a vibration layer having a first side and a second side opposite to the first side, a piezoelectric actuator adjacent to the nozzle and over the first side, a circuit connection over the first side, a first protective layer around the circuit connection, a second protective layer over the piezoelectric actuator, a first water-resistant film over a surface of the first protective layer, and a second water-resistant film over a surface of the second protective layer. The liquid is discharged through the nozzle in a direction from the second side toward the first side. The second protective layer is separated from the first protective layer. The first protective layer defines an opening above the circuit connection. The liquid chamber substrate has a liquid chamber communicating with the nozzle. The drive circuit is disposed over the second side and connected to the circuit connection to drive the piezoelectric actuator. The first protective layer and the second protective layer are discontinuous from each other.

A liquid discharged from the liquid discharge head according to the present embodiment is not particularly limited and can be appropriately changed. The liquid discharge head that discharges ink as the liquid is also referred to as an inkjet head.

A liquid discharge head <NUM> according to the present embodiment is described with reference to <FIG> is a schematic cross-sectional view of the liquid discharge head <NUM> according to the present embodiment. <FIG> is a schematic plan view of the liquid discharge head <NUM> according to the present embodiment as viewed from a nozzle surface side (also referred to as a liquid discharge side from which liquid is discharged). That is, the liquid discharge head <NUM> illustrated in <FIG> is viewed in the direction indicated by arrow a in <FIG> is the schematic cross-sectional view taken along line A-A in <FIG>.

As illustrated in <FIG>, the liquid discharge head <NUM> according to the present embodiment includes a nozzle layer <NUM>, a liquid chamber substrate <NUM>, and a drive circuit <NUM>.

The nozzle layer <NUM> includes a vibration layer <NUM>, a piezoelectric actuator <NUM>, an electrode pad <NUM>, a first protective layer <NUM>, and a second protective layer <NUM>. The electrode pad <NUM> is an example of a circuit connection.

The nozzle layer <NUM> has a nozzle <NUM>, and liquid (for example, ink) is discharged from the nozzle <NUM>. The liquid chamber substrate <NUM> and a part of the nozzle layer <NUM> define a liquid chamber <NUM>, and the piezoelectric actuator <NUM> is driven to discharge the liquid in the liquid chamber <NUM> from the nozzle <NUM>.

The vibration layer <NUM> vibrates when the piezoelectric actuator <NUM> is driven. The material of the vibration layer <NUM> is not particularly limited, and for example, aluminum oxide (Al<NUM>O<NUM>), silicon nitride (SiN), silicon dioxide (SiO<NUM>), high temperature oxide (HTO), or a combination of some of these materials that are laminated one on another can be used.

The liquid chamber substrate <NUM> has the liquid chamber <NUM> communicating with the nozzle <NUM>. A circuit protective layer <NUM> is disposed between the liquid chamber substrate <NUM> and the vibration layer <NUM>. The circuit protective layer <NUM> protects the drive circuit <NUM> and an inter-layer wiring layer <NUM>.

The material of the circuit protective layer <NUM> is not particularly limited, and examples thereof include a polytetrafluoroethylene (PTFE)-based resin. A position where the circuit protective layer <NUM> is formed is not particularly limited, and for example, the circuit protective layer <NUM> is formed so as to cover the drive circuit <NUM> and the inter-layer wiring layer <NUM>. The nozzle layer <NUM> may include the circuit protective layer <NUM>, or the liquid chamber substrate <NUM> may include the circuit protective layer <NUM>.

The piezoelectric actuator <NUM> includes a lower electrode <NUM>, a piezoelectric body <NUM>, and an upper electrode <NUM>. The lower electrode <NUM> may be a common electrode and the upper electrode <NUM> may be an individual electrode. Alternatively, the lower electrode <NUM> may be the individual electrode and the upper electrode <NUM> may be the common electrode.

The material of the piezoelectric body <NUM> is not particularly limited, and for example, lead zirconate titanate (PZT) can be used. The materials of the lower electrode <NUM> and the upper electrode <NUM> are not particularly limited, and known electrode materials can be used. For example, platinum (Pt) may be used.

The piezoelectric actuator <NUM> (the piezoelectric body <NUM>) is disposed adjacent to the nozzle <NUM> and over a side (first side) of the vibration layer <NUM> from which liquid is discharged (i.e., the nozzle surface side). In other words, the piezoelectric actuator <NUM> is disposed on the vibration layer <NUM>. Since the piezoelectric actuator <NUM> is disposed at such a position, a diaphragm plate is unnecessary, which applies pressure to liquid sucked and introduced into the liquid chamber <NUM> to discharge the liquid from the nozzle <NUM>.

In the comparative example, which is not included in embodiments of the present disclosure, a nozzle substrate, a liquid chamber substrate, and the diaphragm plate on which the piezoelectric actuator is disposed are laminated in this order. The configuration of the entire liquid discharge head <NUM> (e.g., the inkjet head) according to the present embodiment can be simplified as compared with the comparative example. In addition, in a manufacturing process of the liquid discharge head <NUM> according to the present embodiment, a process of manufacturing the diaphragm plate, a process of bonding the nozzle substrate, the liquid chamber substrate, a substrate including the piezoelectric actuator, and a frame substrate, and an assembly process can be omitted, thereby significantly reducing manufacturing costs of the liquid discharge head <NUM>.

The piezoelectric actuator <NUM> is connected to the drive circuit <NUM> to drive the piezoelectric actuator <NUM>, via connection electrodes 94b and 94c. For example, the lower electrode <NUM> is connected to the drive circuit <NUM> via the connection electrode 94b, and the upper electrode <NUM> is connected to the drive circuit <NUM> via the connection electrode 94c.

The drive circuit <NUM> is connected to the electrode pad <NUM> via a connection electrode 94a, and is energized from a power supply unit via the electrode pad <NUM> and the connection electrode 94a. The drive circuit <NUM> is disposed over a side (second side) opposite to the side (first side) where the electrode pad <NUM> is disposed across the vibration layer <NUM>. The drive circuit <NUM> is preferably disposed, but not limited to, on one side of the liquid chamber substrate <NUM>. In such a case, the drive circuit <NUM> can be easily formed. Note that the connection electrodes 94a, 94b, and 94c may be collectively referred to as connection electrodes <NUM> unless distinguished.

The drive circuit <NUM> is not particularly limited, but may be, for example, a complementary metal oxide semiconductor (CMOS) circuit. Although not particularly limited, the drive circuit <NUM> is divided into multiple portions connected to the electrode pad <NUM> and connected to the piezoelectric actuator <NUM> as illustrated in <FIG>, and the multiple portions are connected to each other via the inter-layer wiring layer <NUM>. As the material of the inter-layer wiring layer <NUM>, for example, a known electrode material can be used.

The electrode pad <NUM> (i.e., the circuit connection) is disposed over the liquid discharge side (nozzle surface side) of the vibration layer <NUM>, and is connected to the drive circuit <NUM> via the connection electrode 94a. Here, two connection electrodes 94a are illustrated in <FIG>, but the number of the connection electrodes 94a is not limited to two. Two connection electrodes 94b and 94c connected to the lower electrode <NUM> and the upper electrode <NUM> of the piezoelectric actuator <NUM> correspond to the two connection electrodes 94a, respectively.

As illustrated in <FIG>, in the present embodiment, the first and second protective layers <NUM> and <NUM> are disposed over the liquid discharge side (nozzle surface side). The first protective layer <NUM> is disposed around the electrode pad <NUM> and defines an opening <NUM> above the electrode pad <NUM>. The second protective layer <NUM> is disposed over the piezoelectric actuator <NUM>. The first protective layer <NUM> and the second protective layer <NUM> can protect, for example, at least one of the piezoelectric actuator <NUM>, the vibration layer <NUM>, or the electrode pad <NUM>, thereby preventing deterioration of these components.

The materials of the first protective layer <NUM> and the second protective layer <NUM> are not particularly limited, and for example, a polyimide-based resin can be used. The first protective layer <NUM> and the second protective layer <NUM> may be made of the same material or different materials. From the viewpoint of ease of manufacturing, the same material is preferable. Positions where the first protective layer <NUM> and the second protective layer <NUM> are formed are not particularly limited. The first protective layer <NUM> and the second protective layer <NUM> are preferably formed in the entire area or substantially the entire area of the nozzle layer <NUM>.

As illustrated in <FIG>, the first protective layer <NUM> is disposed around the electrode pad <NUM> and defines the opening <NUM> above the electrode pad <NUM>. In the example illustrated in <FIG>, the first protective layer <NUM> and the electrode pad <NUM> are spaced apart, but the first protective layer <NUM> and the electrode pad <NUM> may be in contact with each other in another example. The first protective layer <NUM> does not necessarily surround the entire periphery of the electrode pads <NUM> as illustrated in <FIG>. For example, the first protective layer <NUM> may not be continuous around the electrodes pads <NUM> and may have separated portions.

As illustrated in <FIG>, the second protective layer <NUM> is disposed over the piezoelectric actuator <NUM>. A portion of the second protective layer <NUM> and the vibration layer <NUM> is opened to form the nozzle <NUM>. The opening of the vibration layer <NUM> may be referred to as the nozzle <NUM>, or the opening of the vibration layer <NUM> and the second protective layer <NUM> may be referred to as the nozzle <NUM>.

The liquid discharge head <NUM> according to the present embodiment includes a water-resistant film <NUM> disposed over the surface of the first protective layer <NUM> and the surface of the second protective layer <NUM>. The water-resistant film <NUM> can prevent moisture from permeating into the first and second protective layers <NUM> and <NUM>. Therefore, the piezoelectric actuator <NUM> is prevented from deteriorating in performance due to the moisture permeating through the second protective layer <NUM>. Therefore, the life of the liquid discharge head <NUM> can be extended, and the reliability of the liquid discharge head <NUM> can be improved.

As the water-resistant film <NUM>, for example, Al<NUM>O<NUM>, tantalum dioxide (TaO<NUM>), aluminum nitride (AlN) can be used. The water-resistant film <NUM> is omitted in <FIG> for simplicity.

In the present embodiment, the first protective layer <NUM> and the second protective layer <NUM> are not continuous. As illustrated in <FIG>, the first protective layer <NUM> and the second protective layer <NUM> are separated from each other by a separation groove <NUM>. That is, the first protective layer <NUM> and the second protective layer <NUM> are discontinuous. With such a structure, in the liquid discharge head <NUM> in which the piezoelectric actuator <NUM> and the electrode pad <NUM> (circuit connection) are formed in the nozzle layer <NUM>, the piezoelectric actuator <NUM> is prevented from absorbing moisture from the opening <NUM> above the electrode pad <NUM>, thereby suppressing the deterioration of piezoelectric performance of the piezoelectric actuator <NUM>.

In the comparative example, the piezoelectric actuator may absorb moisture from the opening above the electrode pad, causing the deterioration of piezoelectric performance of the piezoelectric actuator. If moisture in the outside air is absorbed (enters) from the opening above the electrode pad, the moisture erodes the piezoelectric actuator, causing the piezoelectric actuator to deteriorate. The moisture absorption may shorten the life of the inkjet head and may decrease the reliability of the inkjet head.

The comparative example that is not included in embodiments of the present disclosure is described with reference to <FIG>. In the comparative example, the water-resistant film <NUM> is disposed on the surface of a protective layer <NUM>. In this comparative example, the water-resistant film <NUM> is not disposed on a side face of the protective layer <NUM> facing the opening <NUM> above the electrode pad <NUM>, and the side face without the water-resistant film <NUM> is exposed to the outside air. Therefore, moisture in the outside air is absorbed through the protective layer <NUM> and reaches the piezoelectric actuator <NUM>. That is, the moisture is absorbed as indicated by the blank arrow in <FIG>. As a result, the piezoelectric actuator <NUM> may deteriorate.

On the other hand, in the present embodiment, the first protective layer <NUM> and the second protective layer <NUM> are not continuous with each other. Accordingly, even if moisture in the outside air enters through the side face facing the opening <NUM> without the water-resistant film <NUM>, the moisture does not reach and erode the piezoelectric actuator <NUM>. If the first protective layer <NUM> and the second protective layer <NUM> are continuous, for example, if the separation groove <NUM> is not provided, moisture enters between the first and second protective layers <NUM> and <NUM> and the vibration layer <NUM> from the opening <NUM> and reaches the piezoelectric actuator <NUM>. On the other hand, the first protective layer <NUM> and the second protective layer <NUM> are not continuous in the present embodiment. Accordingly, even when moisture enters between the first protective layer <NUM> and the vibration layer <NUM> from the opening <NUM>, the moisture reaches only the separation groove <NUM>. Therefore, the moisture does not affect the piezoelectric actuator <NUM>.

Although the separation groove <NUM> is disposed between the first protective layer <NUM> and the second protective layer <NUM> in the present embodiment, the water-resistant film <NUM> covering the surface (and the side surface) of the second protective layer <NUM> that covers the piezoelectric actuator <NUM> can prevent moisture from entering between the second protective layer <NUM> and the vibration layer <NUM> from the separation groove <NUM>.

The position where the water-resistant film <NUM> is formed can be changed as appropriate, but as illustrated in <FIG>, the water-resistant film <NUM> over the surface of the first protective layer <NUM> (i.e., a first water-resistant film) and the water-resistant film <NUM> over the surface of the second protective layer <NUM> (i.e., a second water-resistant film) are preferably continuous. Such a structure can prevent moisture from entering from the separation groove <NUM>. As a result, the moisture does not permeate into (reach) the piezoelectric actuator <NUM>.

Next, a liquid discharge head <NUM> according to another embodiment of the present disclosure is described. Descriptions of the same items as those in the above embodiment are omitted.

<FIG> illustrates the liquid discharge head <NUM> according to the present embodiment. <FIG> is the cross-sectional view similar to <FIG>. In the liquid discharge head <NUM> according to the present embodiment, the liquid chamber substrate <NUM> is a silicon on insulator (SOI) substrate. In the present embodiment, the SOI substrate includes an insulating layer <NUM> on the side on which the drive circuit <NUM> is disposed.

According to the present embodiment, the liquid chamber substrate <NUM> is the SOI substrate, and in particular, the SOI substrate includes the insulating layer <NUM> on the side on which the drive circuit <NUM> is disposed, thereby reducing a stray capacitance and a leakage current generated in the drive circuit <NUM>. Such a structure can increase the speed of the printing process using the liquid discharge head <NUM> according to the present embodiment and improve the power saving of the liquid discharge head <NUM> and the withstand voltage and reliability of the drive circuit <NUM>.

The structure of the drive circuit <NUM> according to a comparative example may generate a stray capacitance and a leakage current from the drive circuit <NUM>, thereby generating a delay of a signal or a leakage current to the substrate. The structure according to the present embodiment can prevent such a situation.

Also in the present embodiment, the water-resistant film <NUM> described above is provided, thereby further improving the reliability.

Next, a process of manufacturing the liquid discharge head <NUM> according to the above embodiments is described with reference to <FIG>, which are schematic cross-sectional views similar to <FIG> and <FIG> described above. Here, an example in which a normal silicon substrate is used is described, but even in the case where the SOI substrate described above is used, the manufacturing process basically has the same flow.

First, a silicon substrate is prepared as the liquid chamber substrate <NUM> as illustrated in <FIG>. The CMOS circuit as the drive circuit <NUM> and the inter-layer wiring layer <NUM> that connects the drive circuits <NUM> are formed by a general method as illustrated in <FIG>.

Next, the circuit protective layer <NUM> that protects the drive circuit <NUM> and the inter-layer wiring layer <NUM> is formed. Further, the vibration layer <NUM> is formed over the circuit protective layer <NUM> as illustrated in <FIG>. As the material of the circuit protective layer <NUM>, for example, the PTFE-based resin is used, and as the material of the vibration layer <NUM>, for example, Al<NUM>O<NUM>, SiN, SiO<NUM>, HTO, or a combination of some of these materials that are laminated one on another is used.

Next, contact portions (i.e., the connection electrodes 94a) that connect the drive circuit <NUM> and the electrode pad <NUM>, and contact portions (i.e., the connection electrodes 94b and 94c) that connect the drive circuit <NUM> and the piezoelectric actuator <NUM> are formed as illustrated in <FIG>.

The lower electrode <NUM> is formed over the vibration layer <NUM> from Pt as illustrated in <FIG>. A film formation pattern of the lower electrode <NUM> can be formed by photolithography and etching. As illustrated in <FIG>, the electrode pad <NUM> is formed, which serves as the circuit connection for supplying power to the drive circuit <NUM>. Further, as illustrated in <FIG>, with a mask on the lower electrode <NUM> (the liquid chamber substrate <NUM>), the piezoelectric body <NUM> is formed from a piezoelectric material by a process such as chemical vapor deposition (CVD) or physical vapor deposition (PVD), and then the mask is removed. As the piezoelectric material, various materials such as PZT and the like can be selected.

Next, with a mask for wiring, a film is formed from an electrode material, and then the mask is removed. As a result, the upper electrode <NUM> is formed and simultaneously conducted to the connection electrode 94c as illustrated in <FIG>.

Next, a protective layer <NUM> and <NUM> is formed over the upper surfaces of the piezoelectric actuator <NUM> and the electrode pad <NUM> as illustrated in <FIG>. The piezoelectric actuator <NUM> surrounds the position where the nozzle <NUM> is to be formed. In this example, the protective layer <NUM> and <NUM> is formed in the entire area of the nozzle layer <NUM>, but the area on which the protective layer <NUM> and <NUM> is formed is not limited thereto. Note that, in this example, the first protective layer <NUM> and the second protective layer <NUM> are made of the same material (for example, a polyimide-based resin) and collectively referred to as the protective layer <NUM> and <NUM>, which is not separated here.

Next, the liquid chamber <NUM> is formed by photolithography and etching from the back surface (the side opposite to the piezoelectric actuator <NUM>) of the liquid chamber substrate <NUM> as illustrated <FIG>. In this case, the vibration layer <NUM> serves as an etch stop layer.

Next, the protective layer <NUM> and <NUM> formed in the entire area of the nozzle layer <NUM> is processed by photolithography to form a nozzle recess 4a as illustrated in <FIG>. Thus, at a nozzle formation position surrounded by the piezoelectric actuator <NUM>, the protective layer <NUM> and <NUM> is opened so as to coincide with the shape of the nozzle <NUM> to be formed. Further, as illustrated in <FIG>, the separation groove <NUM> that separates the protective layer <NUM> and <NUM> into the first protective layer <NUM> and the second protective layer <NUM> is formed.

Next, the nozzle layer <NUM> (the vibration layer <NUM>) is etched using the second protective layer <NUM>, which is opened by photolithography as described above, as a mask to form the nozzle <NUM> as illustrated in <FIG>. The vibration layer <NUM> in the separation groove <NUM> around the electrode pad <NUM> is also etched at the same time, but the drive circuit <NUM> is protected by the circuit protective layer <NUM> under the vibration layer <NUM>.

Next, the water-resistant film <NUM> is formed from the nozzle surface side as illustrated in <FIG>. The water-resistant film <NUM> is formed over the surface of the first protective layer <NUM> and the surface of the second protective layer <NUM>, for example, by an atomic layer deposition (ALD) method.

Next, portions of the water-resistant film <NUM> and the first protective layer <NUM> above the electrode pad <NUM> are opened with a mask to form the opening <NUM> as illustrated in <FIG>. As a result, a component of the liquid discharge head <NUM> according to the present embodiment is obtained.

Thereafter, the component is combined with another component such as a common liquid chamber substrate which is separately manufactured, thereby completing the liquid discharge head <NUM> having the common liquid chamber. Other components may be combined as appropriate.

As described above, in the manufacturing process of the liquid discharge head <NUM> according to the present embodiment, the process of manufacturing the diaphragm plate, the process of bonding the nozzle substrate, the liquid chamber substrate, the substrate including the piezoelectric actuator, and the frame substrate, and the assembly process can be omitted, thereby significantly reducing manufacturing costs of the liquid discharge head <NUM>.

Next, an example of a liquid discharge apparatus according to the present disclosure is described with reference to <FIG> is a plan view of a part of a liquid discharge apparatus <NUM>. <FIG> is a side view of the part of the liquid discharge apparatus <NUM> in <FIG>.

The liquid discharge apparatus <NUM> is a serial-type apparatus in which a main-scanning moving mechanism <NUM> reciprocates a carriage <NUM> in the main scanning directions indicated by arrow MSD in <FIG>. The main-scanning moving mechanism <NUM> includes a guide <NUM>, a main-scanning motor <NUM>, and a timing belt <NUM>. The guide <NUM> is bridged between left and right side plates 491A and 491B to moveably hold the carriage <NUM>. The main-scanning motor <NUM> reciprocates the carriage <NUM> in the main scanning direction via the timing belt <NUM> looped around a drive pulley <NUM> and a driven pulley <NUM>.

The carriage <NUM> is mounted with a liquid discharge device <NUM> including a plurality of liquid discharge heads <NUM> according to the above described embodiments of the present disclosure and a head tank <NUM> as a single integrated unit. The plurality of liquid discharge heads <NUM> of the liquid discharge device <NUM> discharges color liquids of, for example, yellow (Y), cyan (C), magenta (M), and black (K). The liquid discharge head <NUM> is mounted on the liquid discharge device <NUM> such that a nozzle row including a plurality of nozzles <NUM> is arranged in the sub-scanning direction perpendicular to the main scanning direction. The liquid discharge head <NUM> discharges the color liquid downward.

A supply mechanism <NUM> disposed outside the liquid discharge head <NUM> supplies liquid stored in liquid cartridges <NUM> to the head tank <NUM> of the liquid discharge head <NUM>.

The supply mechanism <NUM> includes a cartridge holder <NUM> which is a filling part to mount the liquid cartridges <NUM>, a tube <NUM>, a liquid feed unit <NUM> including a liquid feed pump, and the like. The liquid cartridge <NUM> is detachably mounted on the cartridge holder <NUM>. The liquid feed unit <NUM> feeds the liquid from the liquid cartridge <NUM> to the head tank <NUM> via the tube <NUM>.

The liquid discharge apparatus <NUM> further includes a conveyance mechanism <NUM> to convey a sheet <NUM>. The conveyance mechanism <NUM> includes a conveyance belt <NUM> as a conveyor and a sub-scanning motor <NUM> to drive the conveyance belt <NUM>.

The conveyance belt <NUM> attracts the sheet <NUM> and conveys the sheet <NUM> to a position facing the liquid discharge head <NUM>. The conveyance belt <NUM> is an endless belt stretched between a conveyance roller <NUM> and a tension roller <NUM>. The sheet <NUM> can be attracted to the conveyance belt <NUM> by electrostatic attraction, air suction, or the like.

The conveyance belt <NUM> circumferentially moves in the sub-scanning direction indicated by arrow SSD in <FIG> as the conveyance roller <NUM> is rotationally driven by the sub-scanning motor <NUM> via a timing belt <NUM> and a timing pulley <NUM>.

On one side of the carriage <NUM> in the main scanning direction, a maintenance mechanism <NUM> that maintains and recovers the liquid discharge head <NUM> is disposed lateral to the conveyance belt <NUM>.

The maintenance mechanism <NUM> includes, for example, a cap <NUM> to cap the nozzle surface (i.e., the surface on which the nozzles <NUM> are formed) of the liquid discharge head <NUM> and a wiper <NUM> to wipe the nozzle surface.

The main-scanning moving mechanism <NUM>, the supply mechanism <NUM>, the maintenance mechanism <NUM>, and the conveyance mechanism <NUM> are mounted onto a housing including the side plates 491A and 491B and a back plate 491C.

In the liquid discharge apparatus <NUM> having the above-described configuration, the sheet <NUM> is fed and attracted onto the conveyance belt <NUM> and conveyed in the sub-scanning direction indicated by arrow SSD as the conveyance belt <NUM> circumferentially moves.

The liquid discharge apparatus further includes a head driver <NUM> to drive the liquid discharge head. The liquid discharge head <NUM> is driven by the head driver <NUM> in response to an image signal while moving the carriage <NUM> in the main scanning direction to discharge liquid onto the sheet <NUM> not in motion, thereby forming an image.

As described above, the liquid discharge apparatus <NUM> includes the liquid discharge head <NUM> according to the above-described embodiments of the present disclosure, thus allowing stable formation of high-quality images.

Next, another example of the liquid discharge device <NUM> according to the present disclosure is described with reference to <FIG> is a plan view illustrating a part of the liquid discharge device <NUM>.

The liquid discharge device <NUM> includes the housing, the main-scanning moving mechanism <NUM>, the carriage <NUM>, and the liquid discharge head <NUM> among components of the liquid discharge apparatus <NUM> described above. The side plates 491A and 491B, and the back plate 491C construct the housing.

The liquid discharge device <NUM> may further include at least one of the maintenance mechanism <NUM> and the supply mechanism <NUM>, which may be attached to the side plate 491B.

Next, still another example of the liquid discharge device <NUM> according to the present disclosure is described with reference to <FIG> is a front view of the liquid discharge device <NUM>.

The liquid discharge device <NUM> includes the liquid discharge head <NUM> to which a channel component <NUM> is attached and tubes <NUM> connected to the channel component <NUM>.

The channel component <NUM> is disposed inside a cover <NUM>. In some embodiments, the liquid discharge device <NUM> may include the head tank <NUM> instead of the channel component <NUM>. A connector <NUM> for electrically connecting to the liquid discharge head <NUM> is provided on an upper portion of the channel component <NUM>.

In the above-described embodiments, the "liquid discharge apparatus" includes the liquid discharge head or the liquid discharge device, and the head driver of the liquid discharge apparatus drives the liquid discharge head (liquid discharge device) to discharge liquid. The liquid discharge apparatus may be, for example, an apparatus capable of discharging liquid to a material onto which liquid can adhere or an apparatus to discharge liquid toward gas or into liquid.

The "liquid discharge apparatus" may include devices relating to feeding, conveyance, and ejection of the material onto which liquid can adhere and also include a pre-treatment device and a post-processing 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 a fabrication liquid to a powder layer in which powder material is formed in layers, so as 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" represents a material onto which liquid is at least temporarily adhered, a material onto 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 materials onto which liquid is adhered, unless particularly limited.

Examples of the "material onto which liquid can adhere" include any materials onto which liquid can adhered even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramic, construction materials (e.g., wall paper or floor material), and cloth textile.

Examples of the "liquid" include ink, treatment liquid, DNA sample, resist, pattern material, binder, fabrication liquid, and solution or liquid dispersion containing amino acid, protein, or calcium.

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. Examples of the liquid discharge apparatus include a serial type apparatus which moves the liquid discharge head, and a line type apparatus which does not move the liquid discharge head.

Examples of the "liquid discharge apparatus" further include a treatment liquid coating apparatus to discharge a treatment liquid to a sheet surface to coat the sheet with the treatment liquid to reform the sheet surface and an injection granulation apparatus to discharge a composition liquid including a raw material dispersed in a solution from a nozzle to granulate fine particles of the raw material.

The "liquid discharge device" refers to a liquid discharge head integrated with functional components or mechanisms, i.e., an assembly of components related to liquid discharge. For example, the "liquid discharge device" includes a combination of the liquid discharge head with at least one of a head tank, a carriage, a supply mechanism, a maintenance mechanism, or a main-scanning moving mechanism.

Here, the integrated unit may be, for example, a combination in which the liquid discharge head and a functional part(s) are secured to each other through, e.g., fastening, bonding, or engaging, and a combination in which one of the liquid discharge head and a functional part(s) is movably held by another. The liquid discharge head may be detachably attached to the functional part(s) or unit(s) each other.

Examples of the liquid discharge device include the liquid discharge device <NUM> in which a liquid discharge head and a head tank are integrated, as illustrated in <FIG>. Alternatively, the liquid discharge head and the head tank coupled (connected) to each other via a tube or the like may form the liquid discharge device as a single unit. Here, a unit including a filter may further be added to a portion between the head tank and the liquid discharge head.

In another example, the liquid discharge device may be an integrated unit in which a liquid discharge head is integrated with a carriage.

As yet another example, the liquid discharge device is a unit in which the liquid discharge head and the main-scanning moving mechanism are combined into a single unit. The liquid discharge head is movably held by a guide that is a part of the main-scanning moving mechanism. Examples of the liquid discharge device further include those in which a liquid discharge head, a carriage, and a main-scanning moving mechanism are integrated, as illustrated in <FIG>.

In another example, the cap that forms a part of the maintenance mechanism is secured to the carriage mounting the liquid discharge head so that the liquid discharge head, the carriage, and the maintenance mechanism are integrated as a single unit to form the liquid discharge device.

Further, in still another example, the liquid discharge device includes tubes connected to the head tank or the liquid discharge head mounting the channel component so that the liquid discharge head and the supply mechanism are integrated as a single unit, as illustrated in <FIG>.

The main-scanning moving mechanism may be a guide only. The supply mechanism may be a tube(s) only or a loading device only.

The liquid discharge head is not limited in the type of pressure generator used. For example, a piezoelectric actuator (which may use a laminated piezoelectric element), a thermal actuator using a thermoelectric conversion element such as a thermal resistor, and an electrostatic actuator including a diaphragm and a counter electrode can be used.

In the present specification, the terms "image formation," "recording," "printing," "image printing," and "fabricating" used herein may be used synonymously with each other.

The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of the present invention.

Claim 1:
A liquid discharge head comprising:
a nozzle layer (<NUM>) having a nozzle (<NUM>) through which a liquid is discharged, the nozzle layer (<NUM>) including:
a vibration layer (<NUM>) having a first side and a second side opposite to the first side, the liquid being discharged through the nozzle (<NUM>) in a direction from the second side toward the first side;
a piezoelectric actuator (<NUM>) adjacent to the nozzle (<NUM>) and over the first side;
a circuit connection (<NUM>) over the first side;
a first protective layer (<NUM>) around the circuit connection (<NUM>), the first protective layer (<NUM>) defining an opening (<NUM>) above the circuit connection (<NUM>);
a second protective layer (<NUM>) over the piezoelectric actuator (<NUM>), the second protective layer (<NUM>) being separated from the first protective layer (<NUM>);
a first water-resistant film (<NUM>) over a surface of the first protective layer (<NUM>); and
a second water-resistant film (<NUM>) over a surface of the second protective layer (<NUM>);
a liquid chamber substrate (<NUM>) having a liquid chamber (<NUM>) communicating the nozzle (<NUM>); and
a drive circuit (<NUM>) over the second side, the drive circuit (<NUM>) being connected to the circuit connection (<NUM>) and configured to drive the piezoelectric actuator (<NUM>),
wherein the first protective layer (<NUM>) and the second protective layer (<NUM>) are discontinuous from each other.