Patent Publication Number: US-9889658-B2

Title: Bonded member, liquid discharge head, liquid discharge device, and liquid discharge apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2015-204243 filed on Oct. 16, 2015 in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     Aspects of the present disclosure relate to a bonded member, a liquid discharge head including the bonded member, a liquid discharge device including the liquid discharge head, and a liquid discharge apparatus including the liquid discharge device. 
     Related Art 
     For example, a liquid discharge head includes head component members, such as a nozzle plate, a channel plate, a wall member, a holding substrate, and a common-liquid-chamber substrate, which are bonded with each other with an adhesive. 
     SUMMARY 
     In an aspect of the present disclosure, there is provided a bonded member that includes at least two members. The at least two members include a first member and a second member bonded to each other. The first member has a bonded face bonded to the second member. The bonded face has a recessed portion at an outer periphery of the bonded face, to retain an adhesive. The recessed portion is open at the bonded face and an outer peripheral face of the first member. In a plan view from a direction vertical to the bonded face, an outer edge of a bottom face of the recessed portion is disposed at an inner position in an in-plane direction of the bonded face than an outer edge of the outer peripheral face of the first member. 
     In another aspect of the present disclosure, there is provided a liquid discharge head that includes the bonded member. 
     In still another aspect of the present disclosure, there is provided a liquid discharge device that includes the liquid discharge head. 
     In still yet another aspect of the present disclosure, there is provided a liquid discharge apparatus that includes the liquid discharge device. 
     In still yet another aspect of the present disclosure, there is provided a liquid discharge apparatus that includes the liquid discharge head. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The aforementioned and other aspects, features, and advantages of the present disclosure would be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an example of a liquid discharge head according to an embodiment of the present disclosure; 
         FIG. 2  is a cross-sectional view of a portion of the liquid discharge head of  FIG. 1  cut along a direction perpendicular to a nozzle array direction in which nozzles are arrayed in row; 
         FIG. 3  is an enlarged cross-sectional view of a portion of the liquid discharge head of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of a portion of the liquid discharge head of  FIG. 2  cut along the nozzle array direction; 
         FIG. 5  is a side view of a bonded member in which a nozzle plate and an actuator substrate are bonded together in a first embodiment of the present disclosure; 
         FIG. 6  is a plan view of a bonded face side of the actuator substrate to be bonded to the nozzle plate in the first embodiment; 
         FIG. 7  is a side view of a long side of the actuator substrate in the first embodiment; 
         FIG. 8  is a side view of a short side of the actuator substrate in the first embodiment; 
         FIG. 9  is an enlarged perspective view of an area around a step portion of the actuator substrate in the first embodiment; 
         FIG. 10  is a cross-sectional view of the area around the step portion of the actuator substrate in the first embodiment; 
         FIG. 11  is a cross-sectional view of the area around the step portion of the actuator substrate, cut along line A-A of  FIG. 10 . 
         FIG. 12  is a plan view of one corner of the actuator substrate in the first embodiment; 
         FIG. 13  is a plan view of one corner of a comparative example; 
         FIG. 14  is a perspective view of a recessed portion in a second embodiment of the present disclosure; 
         FIG. 15  is a cross-sectional view of the recessed portion in the second embodiment; 
         FIG. 16  is a cross-sectional view of a recessed portion in a third embodiment of the present disclosure; 
         FIG. 17  is a plan view of a bonded face side of the actuator substrate to be bonded to the nozzle plate in a fourth embodiment of the present disclosure; 
         FIG. 18  is a side view of a long side of the actuator substrate in the fourth embodiment; 
         FIG. 19  is a cross-sectional view of the recessed portion of the actuator substrate in the fourth embodiment; 
         FIGS. 20A through 20C  are plan views of an example of a production process of the actuator substrate according to the first embodiment; 
         FIGS. 21A through 21C  are enlarged plan views of step portions in the production process; 
         FIG. 22  is an illustration of laser processing; 
         FIG. 23  is an illustration of laser processing; 
         FIG. 24  is a plan view of a portion of a liquid discharge apparatus according to an embodiment of the present disclosure; 
         FIG. 25  is a side view of a portion of the liquid discharge apparatus of  FIG. 24  including a liquid discharge device; 
         FIG. 26  is a plan view of a portion of another example of the liquid discharge device; and 
         FIG. 27  is a front view of still another example of the liquid discharge device. 
     
    
    
     The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results. 
     Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and all of the components or elements described in the embodiments of this disclosure are not necessarily indispensable. 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, exemplary embodiments of the present disclosure are described below. 
     A liquid discharge head according to an embodiment of the present disclosure is described with reference to  FIGS. 1 to 4 .  FIG. 1  is an exploded perspective view of the liquid discharge head according to an embodiment of the present disclosure.  FIG. 2  is a cross-sectional view of the liquid discharge head cut of  FIG. 1  along a direction perpendicular to a nozzle array direction in which nozzles are arrayed in row.  FIG. 3  is an enlarged cross-sectional view of a portion of the liquid discharge head of  FIG. 2 .  FIG. 4  is a cross-sectional view of a portion of the liquid discharge head of  FIG. 2  cut along the nozzle array direction. 
     A liquid discharge head  404  according to the present embodiment includes a nozzle plate  1 , a channel plate  2 , a diaphragm plate  3  as a wall member, piezoelectric elements  11  as pressure generating elements (pressure generators), a holding substrate  50 , a wire  60 , and a frame substrate  70  also serving as a common-liquid-chamber substrate. 
     The channel plate  2 , the diaphragm plate  3 , and the piezoelectric element  11  form an actuator substrate  20  according to the present embodiment. Note that the actuator substrate  20  does not include the nozzle plate  1  or the holding substrate  50  that is bonded to the actuator substrate  20  after the actuator substrate  20  is formed as an independent component. The channel plate  2  and the diaphragm plate  3  form a channel substrate. 
     The nozzle plate  1  includes a plurality of nozzles  4  to discharge liquid. In the present embodiment, the nozzles  4  are arrayed in four rows. 
     With the nozzle plate  1  and the diaphragm plate  3 , the channel plate  2  forms individual liquid chambers  6  communicated with the nozzles  4 , fluid restrictors  7  communicated with the individual liquid chambers  6 , and liquid inlets (passages)  8  communicated with the fluid restrictors  7 . 
     The liquid inlets  8  are communicated with the common liquid chambers  10  in the frame substrate  70  via passages (supply ports)  9  of the diaphragm plate  3  and openings  51  as channels of the holding substrate  50 . 
     The diaphragm plate  3  includes deformable vibration portions  30  forming part of walls of the individual liquid chambers  6 . The piezoelectric element  11  is disposed integrally with the vibration portion  30  on a face of the vibration portion  30  opposite the individual liquid chamber  6 . The vibration portion  30  and the piezoelectric element  11  form a piezoelectric actuator. 
     In the piezoelectric element  11 , a lower electrode  13 , a piezoelectric layer (piezoelectric body)  12 , and an upper electrode  14  are laminated in this order from the vibration portion  30 . An insulation film  21  is disposed on the piezoelectric element  11 . 
     The lower electrode  13  as a common electrode for the plurality of piezoelectric elements  11  is connected to a common-electrode power-supply wiring pattern  121  via a common wire  15 . Note that, as illustrated in  FIG. 4 , the lower electrode  13  is a single electrode layer straddling all of the piezoelectric elements  11  in the nozzle array direction. 
     The upper electrodes  14  as discrete electrodes for the piezoelectric elements  11  are connected to a drive integrated circuit (IC)  500  (hereinafter, driver IC  500 ) as a drive circuit via individual wires  16 . The individual wire  16  is covered with an insulation film  22 . 
     The driver IC  500  are mounted on the actuator substrate  20  by, e.g., a flip-chip bonding method, to cover an area between rows of the piezoelectric elements  11 . 
     The driver IC  500  mounted on the actuator substrate  20  is connected to a discrete-electrode power-supply wiring pattern  101  to which a drive waveform (drive signal) is supplied. 
     One end of the wire  60  is electrically connected to the driver IC  500 . The opposite end of the wire  60  is connected to a controller mounted to an apparatus body. 
     The openings  51  as channels communicating the common liquid chambers  10  with the individual liquid chambers  6  as described above, recessed portions  52  to accommodate the piezoelectric elements  11 , and the holding substrate  50  including openings  53  to accommodate the driver ICs  500  are disposed on the actuator substrates  20 . 
     The holding substrate  50  is bonded to a side of the actuator substrate  20  facing the diaphragm plate  3  with adhesive. 
     The frame substrate  70  includes the common liquid chambers  10  to supply liquid to the individual liquid chambers  6 . Note that, in the present embodiment, the four common liquid chambers  10  are disposed corresponding to the four nozzle rows. Desired colors of liquids are supplied to the respective common liquid chambers  10  via liquid supply ports  71  (see  FIG. 1 ). 
     A damper unit  90  is bonded to the frame substrate  70 . The damper unit  90  includes a damper  91  and damper plates  92 . The damper  91  is deformable and forms part of walls of the common liquid chambers  10 . The damper plates  92  reinforce the damper  91 . 
     The frame substrate  70  is bonded to an outer peripheral portion of the nozzle plate  1 , to accommodate the actuator substrate  20  and the holding substrate  50 , thus forming a frame of the liquid discharge heads  404 . 
     Nozzle covers  45  are disposed to cover part of a peripheral area of the nozzle plate  1  and part of outer circumferential faces of the frame substrate  70 . 
     In the liquid discharge head  404 , voltage is applied from the driver IC  500  to a portion between the upper electrode  14  and the lower electrode  13  of the piezoelectric element  11 . Accordingly, the piezoelectric layer  12  expands in an electrode lamination direction (in other words, an electric-field direction) in which the upper electrode  14  and the lower electrode  13  are laminated, and contracts in a direction parallel to the vibration portion  30 . 
     At this time, since a side (hereinafter, lower electrode  13  side) of the piezoelectric layer  12  facing the vibration portion  30  is bound by the vibration portion  30 , a tensile stress arises at the lower electrode  13  side of the vibration portion  30 , thus causing the vibration portion  30  to bend toward a side (hereinafter, individual liquid chamber  6  side) of the vibration portion  30  facing the individual liquid chamber  6 . Accordingly, liquid within the individual liquid chamber  6  is pressurized and discharged from the nozzle  4 . 
     Next, a first embodiment of the present disclosure is described with reference to  FIGS. 5 through 11 . 
     In bonding two members with an adhesive, to enhance the accuracy of positioning bonded members, for example, the two members are temporarily bonded together with a temporary bonding adhesive to position the two members, and then a final bonding adhesive is cured to finally bond the two members. 
     In such a case, the temporary bonding adhesive is retained on one of the two members. For example, when a light irradiation adhesive, such as an ultraviolet curing adhesive, is used as the temporary bonding adhesive, a portion retaining the temporary bonding adhesive is preferably open at an outer peripheral face of the member. 
     However, when the portion retaining the temporary bonding adhesive is disposed at an outer periphery of the member and is open at the outer peripheral face, the temporary bonding adhesive is likely to extend off to the outer peripheral face of the member. 
     Hence, as described below, according to at least one embodiment of the present disclosure, such extension of adhesive to the outer peripheral face of the member can be reduced. 
       FIG. 5  is a side view of the bonded member in which the nozzle plate and the actuator substrate are bonded together in the first embodiment of the present disclosure.  FIG. 6  is a plan view of a bonded face side of the actuator substrate to be bonded to the nozzle plate.  FIG. 7  is a side view of a long side of the actuator substrate.  FIG. 8  is a side view of a short side of the actuator substrate.  FIG. 9  is an enlarged perspective view of an area around a step portion of the actuator substrate.  FIG. 10  is a cross-sectional view of the area around the step portion of the actuator substrate.  FIG. 11  is a cross-sectional view of the area around the step portion of the actuator substrate, cut along line A-A of  FIG. 10 . 
     In the first embodiment, the nozzle plate  1  is bonded to the actuator substrate  20  including the channel plate  2  with adhesive  80  to form the bonded member. The actuator substrate  20  is one member of the bonded member according to the present embodiment and the nozzle plate  1  is the other member of the bonded member. 
     Here, a face of the actuator substrate  20  to be bonded to the nozzle plate  1  is referred to as a bonded face  20   a . Of side walls at an outer periphery of the actuator substrate  20  crossing the bonded face  20   a , side walls extending in the long direction of the actuator substrate  20  are referred to as outer peripheral faces  20   b   1 , and side walls extending in the short direction are referred to as outer peripheral faces  20   b   2 . The outer peripheral faces  20   b   1  and the outer peripheral faces  20   b   2  are collectively referred to as outer peripheral faces  20   b  unless distinguished. 
     The actuator substrate  20  is rectangular in a plan view seen from a direction vertical to the bonded face  20   a.    
     The actuator substrate  20  includes recessed portions  201  at four corners of the outer periphery of the bonded face  20   a . Each recessed portion  201  is open in three directions to the bonded face  20   a  side, the outer peripheral face  20   b  side, and the outer peripheral face  20   b  side. The recessed portions  201  retain the adhesive  81 . The recessed portions  201  are disposed at line-symmetric positions with respect to a center line O 1  and a center line O 2  of the bonded face  20   a.    
     In the plan view seen from the direction vertical to the bonded face  20   a , an outer edge  211   a  and an outer edge  211   b  of a bottom face  211  of the recessed portion  201  (see also  FIG. 9 ) are located at inner positions in an in-plane direction of the bonded face  20   a  than an outer edge  20   b   11  of the outer peripheral face  20   b   1  and an outer edge  20   b   21  of the outer peripheral face  20   b   2 . 
     In the present embodiment, each of the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2  has a cutout portion  202 . Accordingly, the outer edge  211   a  and the outer edge  211   b  of the bottom face  211  of each recessed portion  201  is receded more inwardly in the in-plane direction of the bonded face  20   a  than the outer edge  20   b   11  of the outer peripheral face  20   b   1  and the outer edge  20   b   21  of the outer peripheral face  20   b   2 . Note that, in  FIG. 9  and  FIG. 10 , imaginary lines extended from the outer peripheral faces  20   b  are illustrated for ease of understanding the cutout portions  202 . In the present embodiment, the cutout portion  202  has a shape penetrating from the bonded face  20   a  to the opposite face of the bonded face  20   a  in a direction of thickness of the actuator substrate  20 . In some embodiments, the cutout portion  202  may be formed at a part of the bonded face  20   a  side of the actuator substrate  20 . 
     As illustrated in  FIG. 10 , a length L 11  of the cutout portion  202  in a direction along a peripheral direction of the actuator substrate  20  (a direction along the outer edge  20   b   21  of the outer peripheral face  20   b   2  in  FIG. 10 ) is longer than a length L 21  of the recessed portion  201  in the direction along the peripheral direction of the actuator substrate  20 . 
     Such a configuration can reliably locate the bottom face  211  of the recessed portion  201  away from the outer peripheral face  20   b  of the actuator substrate  20 . 
     In the present embodiment, when a non-penetrating portion forming the bottom face  211  of the recessed portion  201  is referred to as a step portion  200 , the step portion  200  forming a step face being the bottom face  211  of the outer peripheral face  20   b  is recessed in the in-plane direction of the bonded face  20   a  relative to the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . 
     For example, the recessed portion  201  has an inner wall  212  and an inner wall  213  between the bonded face  20   a  and inner edges of the bottom face  211  crossing each other. The bottom face  211  has no wall between the bonded face  20   a  and each of the outer edge  211   a  and the outer edge  211   b . For such a configuration, the recessed portion  201  is open to the bonded face  20   a  and is also open to the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . 
     A wall  216  between an outer peripheral wall  214  forming a bottom face of one of the cutout portions  202  and the outer peripheral face  20   b   1  of the actuator substrate  20  has a curved shape (or may have an inclined shape). Likewise, a wall  217  between an outer peripheral wall  215  forming a bottom face of another of the cutout portions  202  and the outer peripheral face  20   b   2  of the actuator substrate  20  has a curved shape (or may have an inclined shape). In the present embodiment, the outer peripheral wall  214  and the outer peripheral wall  215  fall from the bottom face  211  of the recessed portion  201  to the opposite face of the bonded face  20   a . In some embodiments, the outer peripheral wall  214  and the outer peripheral wall  215  may not reach the opposite face. 
     Next, an operation effect of the present embodiment is described with reference to  FIG. 12 .  FIG. 12  is a plan view of one corner of the actuator substrate  20  according to the present embodiment. 
     When the actuator substrate  20  and the nozzle plate  1  are bonded together with the adhesive  80 , the adhesive  80  is coated onto the bonded face  20   a  of the actuator substrate  20  and a temporary bonding adhesive  81 , for example, ultraviolet curing adhesive is coated into the recessed portion  201 . 
     Note that, as the adhesive  80 , any suitable adhesive may be used in consideration of mechanical strength, liquid contact properties, modulus of elasticity, and adhesiveness to components. The adhesive may be, for example, epoxy resin adhesive, urethane resin adhesive, or elastomer resin adhesive. As a method of coating the adhesive  80 , for example, a thin-film printing method, a spray coating method, or a dispensing method may be used. 
     The actuator substrate  20  and the nozzle plate  1  are positioned and the temporary bonding adhesive  81  are irradiated and cured with ultraviolet rays. Thus, the actuator substrate  20  and the nozzle plate  1  are temporarily bonded together. 
     At this time, the recessed portion  201  retaining the temporary bonding adhesive  81  is open not only to the bonded face  20   a  of the actuator substrate  20  but also to the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 , thus facilitating the irradiation of ultraviolet rays. 
     When the temporary bonding adhesive  81  is coated into the recessed portion  201 , as illustrated in  FIG. 12 , an excess adhesive  81   a  extending off the recessed portion  201  in the in-plane direction of the bonded face  20   a  moves along and stops on the outer peripheral wall  214  and the outer peripheral wall  215  and the wall  216  and the wall  217  of the cutout portions  202 . In the direction of thickness of the actuator substrate  20  (the direction vertical to the bonded face  20   a ), the excess adhesive  81   a  moves along and stops on the outer peripheral wall  214  and the outer peripheral wall  214  and the outer peripheral wall  215  of the cutout portion  202 . 
     At this time, the outer edge  211   a  and the outer edge  211   b  of the bottom face  211  of the recessed portion  201  are disposed at inner positions in the in-plane direction of the bonded face  20   a  than the outer edge  20   b   11  of the outer peripheral face  20   b   1  and the outer edge  20   b   21  of the outer peripheral face  20   b   2 , respectively. Such a configuration can prevent the excess adhesive  81   a  from reaching the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . 
     In such a case, the outer peripheral wall  214  and the outer peripheral wall  215  of the cutout portion  202  are continuous with the wall  216  and the wall  217  that have a curved shape. Accordingly, increased surface areas of the wall  216  and the wall  217  can be obtained, thus increasing the amount of adhesive retained on the wall  216  and the wall  217 . 
     Such a configuration can reliably prevent the excess adhesive  81   a  extending off the recessed portions  201  from reaching the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . 
     Next, a comparative example is described with reference to  FIG. 13 .  FIG. 13  is a plan view of one corner of the comparative example. 
     For the comparative example, the outer edge  211   a  and the outer edge  211   b  of the bottom face  211  of the recessed portion  201  are disposed at the same positions as the outer edge  20   b   11  of the outer peripheral face  20   b   1  and the outer edge  20   b   21  of the outer peripheral face  20   b   2 , respectively. In other words, the comparative example does not include the cutout portion  202  according to the above-described first embodiment. 
     Accordingly, when the temporary bonding adhesive  81  is coated into the recessed portion  201 , as illustrated in  FIG. 13 , an excess adhesive  81   a  extending off the recessed portion  201  reaches the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . 
     Next, a second embodiment of the present disclosure is described with reference to  FIGS. 14 and 15 .  FIG. 14  is a perspective view of the recessed portion  201  in the second embodiment.  FIG. 15  is a cross-sectional view of the recessed portion  201  in the second embodiment. 
     In the present embodiment, each of the outer peripheral wall  214  and the outer peripheral wall  215  of the cutout portions  202  is an inclined face inclined at an angle θ relative to the outer peripheral face  20   b  in the direction vertical to the bonded face  20   a  (the direction of thickness of the bonded face  20   a ). The amount of recess from the outer peripheral face  20   b  is greater as the outer peripheral wall  215  approaches the opposite face of the bonded face  20   a  in the direction of thickness. In the present embodiment, the outer peripheral wall  214  and the outer peripheral wall  215  are entirely inclined faces. Note that, in some embodiments, each of the outer peripheral wall  214  and the outer peripheral wall  215  may have a partially inclined or curved portion. 
     Such a configuration can obtain increased surface areas of the outer peripheral wall  214  and the outer peripheral wall  215  of the cutout portion  202 , thus increasing the amount of adhesive retained on the outer peripheral wall  214  and the outer peripheral wall  215 . 
     Such a configuration can reliably prevent the excess adhesive  81   a  extending off the recessed portions  201  from reaching the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . 
     Next, a third embodiment of the present disclosure is described with reference to  FIG. 16 .  FIG. 16  is a cross-sectional view of the recessed portion in the third embodiment. 
     In the present embodiment, the outer peripheral wall  215  (or the outer peripheral wall  214 ) of the cutout portion  202  is a curved face (or an inclined face) that varies in the amount of recess from the outer peripheral face  20   b   2 . In contrast with the second embodiment, the amount of recess from the outer peripheral face  20   b   2  is greater as the outer peripheral wall  215  approaches the opposite face of the bonded face  20   a  in the direction of thickness. In the present embodiment, the outer peripheral wall  215  is entirely an inclined face. Note that, in some embodiments, the outer peripheral wall  215  may have a partially inclined or curved portion. 
     Next, a fourth embodiment of the present disclosure is described with reference to  FIGS. 17 to 19 .  FIG. 17  is a plan view of a bonded face side of the actuator substrate to be bonded to the nozzle plate.  FIG. 18  is a side view of a long side of the actuator substrate.  FIG. 19  is a cross-sectional view of the recessed portion of the actuator substrate. 
     For the present embodiment, the recessed portion  201  and the cutout portion  202  are disposed midway of each side of the actuator substrate  20  of a rectangular shape. In the present embodiment, the recessed portion  201  and the cutout portion  202  are disposed on the center line O 1  or the center line O 2  of the bonded face  20   a . The third embodiment differs from the first embodiment and the second embodiment in that the recessed portion  201  is open to the outer peripheral face  20   b  at only one side and surrounded at three sides. 
     The length L 11  of the cutout portion  202  in the direction along a peripheral direction of the actuator substrate  20  is longer than the length L 21  of the recessed portion  201  the direction along a peripheral direction of the actuator substrate  20 . 
     Accordingly, a wall  226  and a wall  227  connecting an outer peripheral wall  225 , which is a bottom face of the cutout portion  202 , with the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2  are substantially vertical to the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . In the present embodiment, the outer peripheral wall  225  falls from the bottom face  211  of the recessed portion  201  to the opposite face of the bonded face  20   a . In some embodiments, the outer peripheral wall  225  may not reach the opposite face. 
     With such a configuration, the outer edge  211   a  and the outer edge  211   b  of the bottom face  211  of the recessed portion  201  are disposed at inner positions in the in-plane direction of the bonded face  20   a  than the outer edge  20   b   21  of the outer peripheral face  20   b   2  and the outer edge  20   b   11  of the outer peripheral face  20   b   1 , respectively. Such a configuration can retain an excess adhesive extending off the recessed portion  201  with the outer peripheral wall  225  and the wall  226  and the wall  227 , thus preventing the excess adhesive from reaching the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . 
     Next, an example of a process of producing the actuator substrate according to the above-described first embodiment is described with reference to  FIGS. 20A through 20C  and  FIGS. 21A through 21C .  FIGS. 20A through 20C  are plan views of the actuator substrate according to the above-described first embodiment in the production process.  FIGS. 21A through 21C  are enlarged plan views of step portions in the production process. 
     In the present embodiment, as illustrated in  FIG. 20A , for example, a plurality of actuator substrates  20  is formed on a silicon wafer  300 . The silicon wafer  300  are cut along scheduled cutting lines  301  and divided into individual pieces of the actuator substrates  20  (chips). 
     As illustrated in  FIGS. 20A and 21B , non-penetrating recessed portions  302 , which are to be the recessed portions  201  after dicing, are formed by etching crossing portions of the scheduled cutting lines  301 , which are to be four corners of the separate actuator substrates  20  after dicing. The non-penetrating recessed portions  302  do not penetrate through the wafer  300 . 
     As illustrated in  FIGS. 20B and 21B , slits  303 , which are to be the cutout portions  202  after dicing, are formed by etching the crossing portions of the scheduled cutting lines  301  and the non-penetrating recessed portions  302 . The slits  303  penetrate through the wafer  300 . 
     Note that the slits  303  are preferably formed by, for example, wet etching. Surface roughening by wet etching can enhance the bonding force of adhesive with the wall by anchor effect when the adhesive extends off the recessed portion  201 , thus reducing dropping of the adhesive. 
     As illustrated in  FIGS. 20C and 21C , dicing is performed along the scheduled cutting lines  301  and cutting process is performed as indicated by processing lines (dicing lines)  304 . 
     Stress is applied to the wafer  300  by, e.g., expanding, thus dividing the wafer  300  into the individual pieces of the actuator substrates  20  (chips). 
     Dicing is performed by, for example, a method of cutting the wafer  300  with a rotary edge (blade) or a method of cutting the wafer  300  by melting or vaporizing cutting portions with thermal energy of laser light. For the method of cutting the wafer  300  with the blade, the blade is used that has a smaller width than the width of the slit  303 . Alternatively, for the method of cutting the wafer  300  with the laser light, the spot diameter of laser light is set to be smaller than the width of the slit  303 . 
     Stealth dicing is preferably used. In comparison with blade dicing setting a cutting margin corresponding to the width of the blade, stealth dicing can divide the wafer  300  into the individual pieces of the actuator substrates  20  (chips) without such a cutting margin. Accordingly, the non-penetrating recessed portion  302 , which is to be the recessed portion  201 , can be disposed at inner positions than the outer peripheral face of the chip (the actuator substrate  20 ). 
     Stealth dicing is a laser processing method of dividing a plate-shaped workpiece, such as a wafer, with pulse laser light having transparency relative to the workpiece by emitting the pulse laser light with a focal point set on the inside of a target area to be divided. 
     For the dividing method using the laser processing method, the pulse laser light of a wavelength (e.g., 1064 nm) having transparency relative to the workpiece is emitted with the focal point set on the inside of the workpiece from one face of the workpiece, to form continuously form an altered layer along a street inside the workpiece. The workpiece is divided by applying an external force along the street, which has a decreased strength due to the formation of the altered layer. 
     For the processing with the laser processing method, as illustrated in  FIG. 22 , when the non-penetrating recessed portion  302  is formed in a scanning area of laser light  400  to form a step portion, the focal point is different between the surface of the wafer  300  and the bottom face of the non-penetrating recessed portion  302 , thus causing a reduced processing accuracy and a processing failure. In such a case, the focal point can be adjusted with a reduced productivity. 
     Hence, as described above, a step structure portion formed by the non-penetrating recessed portion  302  is processed by, e.g., etching to preliminarily form the slit  303  penetrating through the wafer  300  as illustrated in  FIG. 23 . 
     Accordingly, the step structure portion is eliminated in the scanning area of the laser light, thus allowing the wafer  300  to be processed at high productivity and high accuracy without changing a laser property (the focal point) at the recessed portion. 
     In such a case, as illustrated in  FIGS. 21A through 21C , the length L 1  of the slit  303  in the longitudinal direction of the slit  303  is longer than the length L 2  of the non-penetrating recessed portion  302  in the same direction as the longitudinal direction of the slit  303 . 
     Such a configuration can reliably dispose the recessed portion  201  away from the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2  as described above, thus more reliably preventing the adhesive extending off the recessed portion  201  from spreading over the outer peripheral face  20   b   1  and the outer peripheral face  20   b   2 . 
     The length W 1  of the slit  303  in a transverse direction of the slit  303  is shorter than the width W 2  of the non-penetrating recessed portion  302  in a transverse direction of the non-penetrating recessed portion  302  and longer than the spot diameter of laser light (corresponding to the width D illustrated in  FIG. 21C ). Such a configuration prevents laser light from scanning the non-penetrating recessed portions  302 . 
     In the above-described embodiments, the recessed portions and the cutout portions are formed in the actuator substrates (the channel substrate or the channel plate) in the liquid discharge head. In some embodiments, the recessed portions and the cutout portions may be formed in, for example, the nozzle plate. 
     The bonded member is not limited to the bonded member of the actuator substrate and the nozzle plate. In some embodiments, the bonded member may be a bonded member of the actuator substrate and the holding substrate or a bonded member of the holding substrate and one of the common-liquid-chamber substrate and the frame substrate. 
     Alternatively, for example, the bonded member may be a bonded member of two members of a device other than the liquid discharge head. 
     Next, an example of a liquid discharge apparatus according to an embodiment of the present disclosure is described with reference to  FIGS. 24 and 25 .  FIG. 24  is a plan view of a portion of the liquid discharge apparatus according to an embodiment of the present disclosure.  FIG. 25  is a side view of a portion of the liquid discharge apparatus. 
     A liquid discharge apparatus  100  according to the present embodiment is a serial-type apparatus in which a main scan moving unit  493  reciprocally moves a carriage  403  in a main scanning direction indicated by arrow MSD in  FIG. 24 . The main scan moving unit  493  includes, e.g., a guide  401 , a main scanning motor  405 , and a timing belt  408 . The guide  401  is laterally bridged between a left side plate  491 A and a right side plate  491 B and supports the carriage  403  so that the carriage  403  is movable along the guide  401 . The main scanning motor  405  reciprocally moves the carriage  403  in the main scanning direction MSD via the timing belt  408  laterally bridged between a drive pulley  406  and a driven pulley  407 . 
     The carriage  403  mounts a liquid discharge device  440  in which the liquid discharge head  404  and a head tank  441  are integrated as a single unit. The liquid discharge head  404  of the liquid discharge device  440  discharges ink droplets of respective colors of yellow (Y), cyan (C), magenta (M), and black (K). The liquid discharge head  404  includes nozzle rows, each including a plurality of nozzles  4  arrayed in row in a sub-scanning direction, which is indicated by arrow SSD in  FIG. 24 , perpendicular to the main scanning direction MSD. The liquid discharge head  404  is mounted to the carriage  403  so that ink droplets are discharged downward. 
     The liquid stored outside the liquid discharge head  404  is supplied to the liquid discharge head  404  via a supply unit  494  that supplies the liquid from a liquid cartridge  450  to the head tank  441 . 
     The supply unit  494  includes, e.g., a cartridge holder  451  as a mount part to mount liquid cartridges  450 , a tube  456 , and a liquid feed unit  452  including a liquid feed pump. The liquid cartridges  450  are detachably mounted to the cartridge holder  451 . The liquid is supplied to the head tank  441  by the liquid feed unit  452  via the tube  456  from the liquid cartridges  450 . 
     The liquid discharge apparatus  100  includes a conveyance unit  495  to convey a sheet  410 . The conveyance unit  495  includes a conveyance belt  412  as a conveyor and a sub-scanning motor  416  to drive the conveyance belt  412 . 
     The conveyance belt  412  electrostatically attracts the sheet  410  and conveys the sheet  410  at a position facing the liquid discharge head  404 . The conveyance belt  412  is an endless belt and is stretched between a conveyance roller  413  and a tension roller  414 . The sheet  410  is attracted to the conveyance belt  412  by electrostatic force or air aspiration. 
     The conveyance roller  413  is driven and rotated by the sub-scanning motor  416  via a timing belt  417  and a timing pulley  418 , so that the conveyance belt  412  circulates in the sub-scanning direction SSD. 
     At one side in the main scanning direction MSD of the carriage  403 , a maintenance unit  420  to maintain and recover the liquid discharge head  404  in good condition is disposed on a lateral side of the conveyance belt  412 . 
     The maintenance unit  420  includes, for example, a cap  421  to cap a nozzle face (i.e., a face on which the nozzles are formed) of the liquid discharge head  404  and a wiper  422  to wipe the nozzle face. 
     The main scan moving unit  493 , the supply unit  494 , the maintenance unit  420 , and the conveyance unit  495  are mounted to a housing that includes the left side plate  491 A, the right side plate  491 B, and a rear side plate  491 C. 
     In the liquid discharge apparatus  100  thus configured, the sheet  410  is conveyed on and attracted to the conveyance belt  412  and is conveyed in the sub-scanning direction SSD by the cyclic rotation of the conveyance belt  412 . 
     The liquid discharge head  404  is driven in response to image signals while the carriage  403  moves in the main scanning direction MSD, to discharge liquid to the sheet  410  stopped, thus forming an image on the sheet  410 . 
     As described above, the liquid discharge apparatus  100  includes the liquid discharge head  404  according to an embodiment of the present disclosure, thus allowing stable formation of high quality images. 
     Next, another example of the liquid discharge device according to an embodiment of the present disclosure is described with reference to  FIG. 26 .  FIG. 26  is a plan view of a portion of another example of the liquid discharge device (liquid discharge device  440 A). 
     The liquid discharge device  440 A includes the housing, the main scan moving unit  493 , the carriage  403 , and the liquid discharge head  404  among components of the liquid discharge apparatus  100 . The left side plate  491 A, the right side plate  491 B, and the rear side plate  491 C form the housing. 
     Note that, in the liquid discharge device  440 A, at least one of the maintenance unit  420  and the supply unit  494  may be mounted on, for example, the right side plate  491 B. 
     Next, still another example of the liquid discharge device according to an embodiment of the present disclosure is described with reference to  FIG. 27 .  FIG. 27  is a front view of still another example of the liquid discharge device (liquid discharge device  440 B). 
     The liquid discharge device  440 B includes the liquid discharge head  404  to which a channel part  444  is mounted, and the tube  456  connected to the channel part  444 . 
     Further, the channel part  444  is disposed inside a cover  442 . Instead of the channel part  444 , the liquid discharge device  440 B may include the head tank  441 . A connector  443  to electrically connect the liquid discharge head  404  to a power source is disposed above the channel part  444 . 
     In the above-described embodiments of the present disclosure, the liquid discharge apparatus includes the liquid discharge head or the liquid discharge device, and drives the liquid discharge head to discharge liquid. The liquid discharge apparatus may be, for example, an apparatus capable of discharging liquid to a material to which liquid can adhere and an apparatus to discharge liquid toward gas or into liquid. 
     The liquid discharge apparatus may include devices to feed, convey, and eject the material on which liquid can adhere. The liquid discharge apparatus may further include a pretreatment apparatus to coat a treatment liquid onto the material, and a post-treatment apparatus to coat a treatment liquid onto the material, onto which the liquid has been discharged. 
     The liquid discharge apparatus may be, for example, an image forming apparatus to discharge liquid to form an image on a medium or a solid fabricating apparatus (three-dimensional fabricating apparatus) to discharge a fabrication liquid to a powder layer in which powder is formed in layers to form a solid fabricating object (three-dimensional object). 
     The liquid discharge apparatus is not limited to an apparatus to discharge liquid to visualize meaningful images, such as letters or figures. For example, the liquid discharge apparatus may be an apparatus to form meaningless images, such as meaningless patterns, or fabricate three-dimensional images. 
     The above-described material to which liquid can adhere may include any material to which liquid may adhere even temporarily. The material to which liquid can adhere may be, e.g., paper, thread, fiber, fabric, leather, metal, plastics, glass, wood, and ceramics, to which liquid can adhere even temporarily. 
     The liquid may be, e.g., ink, treatment liquid, DNA sample, resist, pattern material, binder, and mold liquid. 
     The liquid discharge apparatus may be, unless in particular limited, any of a serial-type apparatus to move the liquid discharge head and a line-type apparatus not to move the liquid discharge head. 
     The liquid discharge apparatus may be, for example, a treatment liquid coating apparatus to discharge a treatment liquid to a sheet to coat the treatment liquid on the surface of the sheet to reform the sheet surface or an injection granulation apparatus in which a composition liquid including raw materials dispersed in a solution is injected through nozzles to granulate fine particles of the raw materials. 
     The liquid discharge device is an integrated unit including the liquid discharge head and a functional part(s) or unit(s), and is an assembly of parts relating to liquid discharge. For example, the liquid discharge device may be a combination of the liquid discharge head with at least one of the head tank, the carriage, the supply unit, the maintenance unit, and the main scan moving unit. 
     Here, examples of the integrated unit include 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) s each other. 
     For example, like the liquid discharge device  440  illustrated in  FIG. 25 , the liquid discharge device may be the integrated unit in which the liquid discharge head and the head tank are integrated. The liquid discharge head and the head tank may be connected each other via, e.g., a tube to form the liquid discharge device as the integrated 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. 
     In still another example, the liquid discharge device may include the liquid discharge head movably held by the guide that forms part of the main scan moving unit, so that the liquid discharge head and the main scan moving unit are integrated as a single unit. Like the liquid discharge device  440 A illustrated in  FIG. 26 , the liquid discharge device may be an integrated unit in which the liquid discharge head, the carriage, and the main scan moving unit are integrally formed as a single unit. 
     In another example, the cap that forms part of the maintenance unit is secured to the carriage mounting the liquid discharge head so that the liquid discharge head, the carriage, and the maintenance unit are integrated as a single unit to form the liquid discharge device. 
     Like the liquid discharge device  440 B illustrated in  FIG. 27 , the liquid discharge device may be an integrated unit in which the tube is connected to the liquid discharge head mounting the head tank or the channel part so that the liquid discharge head and the supply unit are integrally formed. 
     The main-scan moving unit may be a guide only. The supply unit may be a tube(s) only or a loading unit only. 
     The pressure generator used in the liquid discharge head is not limited to a particular-type of pressure generator. The pressure generator is not limited to the piezoelectric actuator (or a layered-type piezoelectric element) described in the above-described embodiments, and may be, for example, a thermal actuator that employs a thermoelectric conversion element, such as a thermal resistor or an electrostatic actuator including a diaphragm and opposed electrodes. 
     The terms “image formation”, “recording”, “printing”, “image printing”, and “molding” used herein may be used synonymously with each other. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the above teachings, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims.