Patent Publication Number: US-2023139963-A1

Title: Liquid discharge head and liquid discharge apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2021-176427, filed on Oct. 28, 2021, in the Japan Patent Office, and Japanese Patent Application No. 2022-121491, filed on Jul. 29, 2022, in the Japan Patent Office the entire disclosure of which are hereby incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     The present embodiment relates to a liquid discharge head and a liquid discharge apparatus. 
     Related Art 
     As liquid discharge apparatuses that discharge a liquid, there are known inkjet image forming apparatuses that discharge an ink onto a sheet such as paper to form an image. 
     Inkjet image forming apparatuses include a liquid discharge head having a nozzle to discharge the ink. When a sheet is conveyed to a position facing the liquid discharge head, the ink is discharged through the nozzle to form an image on the sheet. When the sheet comes into contact with the nozzle, the nozzle may be damaged, which may avoid stable ink discharge. Therefore, some inkjet image forming apparatuses include a nozzle protector that protects the nozzle. 
     SUMMARY 
     A liquid discharge head includes: a nozzle plate having: a nozzle surface; and a nozzle in the nozzle plate, a liquid being discharged from the nozzle of the nozzle surface side in a liquid discharge direction; a nozzle protector covering at least a part of the nozzle surface of the nozzle plate other than the nozzle; a nozzle protector holder including a peripheral wall bonded to a peripheral end portion of the nozzle protector; and a resin member between an edge face of the peripheral end portion of the nozzle protector and an end surface of the peripheral wall facing the nozzle protector. 
     According to the present embodiment, it is possible to suppress the separation of the nozzle protector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings, wherein: 
         FIG.  1    is a diagram illustrating a general arrangement of an inkjet image forming apparatus according to an embodiment. 
         FIG.  2    is a block diagram illustrating a control system of the inkjet image forming apparatus according to the embodiment. 
         FIG.  3    is an exploded perspective view of an example of a configuration of a liquid discharge head. 
         FIG.  4    is a cross-sectional view of the liquid discharge head illustrated in  FIG.  3    in a lateral direction. 
         FIG.  5    is a plan view of an example of a configuration of a line head unit. 
         FIG.  6    is a plan view of an example of a configuration of a serial head unit. 
         FIG.  7    is a schematic cross-sectional view of the liquid discharge head according to a first embodiment. 
         FIG.  8    is a plan view of the liquid discharge head according to the first embodiment. 
         FIG.  9    is a schematic cross-sectional view of the liquid discharge head according to a second embodiment. 
         FIG.  10    is a schematic cross-sectional view of the liquid discharge head according to a third embodiment. 
         FIG.  11    is a schematic cross-sectional view of the liquid discharge head according to a fourth embodiment. 
         FIG.  12    is a schematic cross-sectional view of the liquid discharge head according to a comparative example. 
     
    
    
     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. Also, identical or similar reference numerals designate identical or similar components throughout the several views. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this 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 have a similar function, operate in a similar manner, and achieve a similar result. 
     Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     Embodiments will be described below with reference to the accompanying drawings. In each of the drawings for describing the embodiments, components such as members and elements having the same function or shape will be denoted by the same reference numeral as long as the components are distinguishable, and thus the description thereof will be omitted after the components are described once. 
     First, a configuration of an inkjet image forming apparatus, which is a liquid discharge apparatus according to an embodiment, will be described with reference to  FIGS.  1  and  2   .  FIG.  1    is a diagram illustrating a general arrangement of the inkjet image forming apparatus, and  FIG.  2    is a block diagram illustrating a control system of the inkjet image forming apparatus. 
     As illustrated in  FIG.  1   , an image forming apparatus  100  according to the present embodiment includes a sheet supplier  1  that supplies a sheet S for image formation, an image former  2  that forms an image on the sheet S, a conveyer  3  that conveys the sheet S to the image former  2 , a dryer  4  that dries the sheet S, and a sheet collector  5  that collects the sheet S having an image formed thereon. The image forming apparatus  100  according to the present embodiment further includes a controller  6  (see  FIG.  2   ) that controls the sheet supplier  1 , the image former  2 , the conveyer  3 , the dryer  4 , and the sheet collector  5 . 
     The sheet supplier  1  includes a supply roller  11  having the elongated sheet S wound in roll form and a tension adjustment mechanism  12  that adjusts the tension applied to the sheet S. The supply roller  11  is configured to rotate in the direction of an arrow illustrated in  FIG.  1    so that, as the supply roller  11  rotates, the sheet S is delivered. The tension adjustment mechanism  12  includes a plurality of rollers that has the sheet S placed therebetween to apply the tension. A part of these rollers is moved to adjust the tension of the sheet S. and the sheet S is delivered from the supply roller  11  at a constant tension. 
     The image former  2  includes a head unit  13 , which includes a liquid discharge unit that ejects a liquid ink onto the sheet S. and a platen  14 , which includes a sheet support member that supports the conveyed sheet S. The head unit  13  includes a plurality of liquid discharge heads. The ink is ejected from each of the liquid discharge heads onto the sheet S based on the image data generated by the controller  6  so that the image is formed on the sheet S. Here, the ink includes a liquid containing a color material, a solvent, and crystalline resin particles dispersed in the solvent. The crystalline resin includes a resin that undergoes a phase change and melts from a crystalline state to a liquid when heated above a predetermined melting point. The platen  14  is positioned so as to face the head unit  13  and support the lower surface of the sheet S supplied from the sheet supplier  1 . The platen  14  is configured to be close to or away from the head unit  13  so that the distance between the head unit  13  and the sheet S may be kept constant. 
     The conveyer  3  includes a plurality of conveyance rollers  15 . Each of the conveyance rollers  15  rotates while the sheet S is placed between the conveyance rollers  15 , and thus the sheet S is conveyed to the image former  2 . The conveyer  3  may also include other conveyers such as a conveyance belt. 
     The dryer  4  includes a heating drum  16  that heats the sheet S to promote drying of the ink on the sheet S. The heating drum  16  includes a cylindrical member that rotates while the sheet S is wound around the outer circumference thereof and has a heating source such as a halogen heater located inside. In addition to a contact heater such as the heating drum  16 , a non-contact heater such as a warm air generation device that blows warm air to the sheet S may also be used as a heater that heats the sheet S. 
     The sheet collector  5  includes a collection roller  17  that winds and collects the sheet S and a tension adjustment mechanism  18  that adjusts the tension applied to the sheet S. The collection roller  17  is configured to rotate in the direction of an arrow illustrated in  FIG.  1    so that, as the collection roller  17  rotates, the sheet S is wound and collected in roll form. The tension adjustment mechanism  18  includes a plurality of rollers, as in the tension adjustment mechanism  12  in the sheet supplier  1 . A part of these rollers is moved to adjust the tension of the sheet S, and the sheet S is wound by the collection roller  17  at a constant tension. 
     The controller  6  includes an information processing apparatus such as a personal computer (PC). The controller  6  generates image data to be formed on the sheet S and controls various operations of the sheet supplier  1 , the image former  2 , the conveyer  3 , the dryer  4 , and the sheet collector  5 . For example, the controller  6  controls the rotation speeds of the supply roller  11 , the collection roller  17 , and each of the conveyance rollers  15 , and the temperature of the heating source that heats the heating drum  16 . 
     Next, an example of the configuration of the liquid discharge head will be described with reference to  FIGS.  3  and  4   . 
       FIG.  3    is an exploded perspective view of the liquid discharge head.  FIG.  4    is a cross-sectional view of the liquid discharge head illustrated in  FIG.  3    in the lateral direction (the direction of an arrow Y in  FIG.  3   ). 
     As illustrated in  FIG.  3   , a liquid discharge head  20  includes a plurality of head main bodies  21 , a base  22 , a cover  23 , a heat dissipation member  24 , a manifold  25 , a printed circuit board  26  (PCB), and a module case  27 . 
     The head main bodies  21  are held by the base  22  as a holder. To attach the head main body  21  to the base  22 , the head main body  21  is first inserted into an opening  22   c  (see  FIG.  4   ) included in the base  22 . Then, the head main body  21  is bonded to the cover  23  that is bonded to the base  22 . The cover  23  includes a hole  23   a  (see  FIG.  3   ) corresponding to each of the head main bodies  21  so that a peripheral portion of the head main body  21  is bonded to an edge of the hole  23   a . Then, the head main body  21  is fastened and secured to the base  22  with a screw. 
     Specifically, a flange portion of a common channel member  35  (see  FIG.  4   ) is provided on the front side and the back side of the head main body  21  in the longitudinal direction (the direction perpendicular to the paper surface of  FIG.  4   ), and the flange portion is fastened to the base  22  with a screw. 
     Accordingly, the common channel member  35  is held by the base  22 , and the head main body  21  is secured. The attachment structure of the head main body  21  and the base  22  is not limited thereto, and the head main body  21  may also be attached by bonding, swage, etc. 
     As illustrated in  FIG.  4   , the head main body  21  includes a nozzle plate  31  having a nozzle  30 , a channel  32  including an individual chamber  41 , or the like, communicating with the nozzle  30 , a diaphragm  33  including a piezoelectric element  40 , a holding  34  laminated on the diaphragm  33 , the common channel member  35  stacked on the holding  34 , etc. The common channel member  35  serves as a frame (nozzle protector holder) to hold the nozzle protector (cover  23 ). The individual chamber  41  is an example of a channel in the channel  32 . 
     The channel  32  includes, in addition to the individual chamber  41 , a supply-side individual channel  42  communicating with the individual chamber  41  and a collection-side individual channel  43  communicating with the individual chamber  41 . The holding  34  includes a supply-side intermediate individual channel  44  communicating with the supply-side individual channel  42  through an opening  33   a  of the diaphragm  33  and a collection-side intermediate individual channel  45  communicating with the collection-side individual channel  43  via an opening  33   b  of the diaphragm  33 . 
     The common channel member  35  (frame) includes a supply-side common channel  46  communicating with the supply-side intermediate individual channel  44  and a collection-side common channel  47  communicating with the collection-side intermediate individual channel  45 . The supply-side common channel  46  communicates with a supply port  48  through a channel  51  in the manifold  25 . 
     The collection-side common channel  47  communicates with a collection port  49  through another channel  52  in the manifold  25 . 
     The PCB  26  is coupled to the piezoelectric element  40  of the head main body  21  through a flexible wiring member  50 . The flexible wiring member  50  has a driver integrated circuit (IC) (drive circuit)  53  mounted thereon. 
     The base  22  preferably has a material having a low coefficient of linear expansion. Examples of the material having a low coefficient of linear expansion include 42 alloy, which is iron with nickel added, or Invar® materials. When the base  22  has such a material, an increase in the temperature of the base  22  due to the heat generated by the liquid discharge head  20  causes a small amount of expansion of the base  22 , which is unlikely to cause a misalignment of the nozzle, and the misalignment of the ink discharge position may be suppressed. When the nozzle plate  31  and the diaphragm  33  include a silicon single-crystal and have the coefficient of linear expansion substantially the same as that of the base  22 , the misalignment of the nozzle due to thermal expansion may be further reduced. 
       FIG.  5    is a plan view of an example of the configuration of the head unit. 
     In the example illustrated in  FIG.  5   , the head unit  13  includes the two liquid discharge heads  20 . Each of the liquid discharge heads  20  is arranged such that the lateral direction thereof (the direction of the arrow Y) is in a sheet conveyance direction A and the longitudinal direction thereof (the direction of an arrow X) is in the direction perpendicular to the sheet conveyance direction A. Here, the “longitudinal direction” of the liquid discharge head  20  means, as illustrated in  FIG.  5   , the longitudinal direction (the direction of the arrow X) of the liquid discharge head  20  extending in one direction when the liquid discharge head  20  is viewed in a direction perpendicular to a nozzle surface  31   a  where the nozzle  30  (see  FIG.  4   ) is exposed. The “lateral direction” of the liquid discharge head  20  means the direction (the direction of the arrow Y) perpendicular to the longitudinal direction of the liquid discharge head  20  when the liquid discharge head  20  is viewed in the direction perpendicular to the nozzle surface  31   a . The “longitudinal direction” and “lateral direction” of the liquid discharge head  20  described in the description below also have the same meanings. 
     The head unit  13  illustrated in  FIG.  5    includes what is called a line head unit. When the sheet S is conveyed to a position facing the head unit  13 , the ink is ejected through the nozzle of each of the head main bodies  21  to form an image on the sheet S without moving the head unit  13  with respect to the conveyed sheet S. 
     In addition to the above-described line head unit, the head unit also includes what is called a serial head unit that ejects the ink while moving the liquid discharge head in the main scanning direction (sheet width direction). 
       FIG.  6    is a diagram illustrating an example of the configuration of a serial head unit  60 . As illustrated in  FIG.  6   , the serial head unit  60  includes a carriage  62  including a liquid discharge head  61 , a guide member  63  (guide rod) that guides the carriage  62  in the main scanning direction, which is a sheet width direction B, and a drive device  64  that moves the carriage  62 . 
     The drive device  64  includes, for example, a motor  65 , which includes a drive source, and a timing belt  68  that extends between a drive pulley  66  and a driven pulley  67 . When the motor  65  is driven and the drive pulley  66  is rotated, the timing belt  68  moves circumferentially, and thus the carriage  62  moves in the main scanning direction along the guide member  63 . The rotation direction of the motor  65  is switched between one direction and the opposite direction so that the carriage  62  may move back and forth in the main scanning direction. 
     In the above-described serial head unit  60 , the liquid discharge head  61  ejects the ink in accordance with the image signal while the carriage  62  moves in the main scanning direction, and thus the image corresponding to one line is formed on the stopped sheet S. Then, while the sheet S moves by a predetermined amount in the direction of the arrow A in  FIG.  6   , the back-and-forth movement of the carriage  62  and the ink discharge are repeatedly performed to sequentially form images on the sheet S. 
     In the above-described head unit (liquid discharge head), as illustrated in  FIG.  3   , the cover  23  is provided around the head main body  21 , and therefore, even when the sheet is conveyed close to the nozzle surface of the head main body  21 , the contact of the sheet with the cover  23  may prevent the contact of the sheet with the nozzle surface. This may prevent damages to the nozzle and maintain stable ink discharge. 
     However, when the conveyed sheet hits an outer edge face  230  of the cover  23 , the impact received by the cover  23  at that moment may cause the cover  23  to separate from the nozzle plate  31 , the base  22  (see  FIG.  4   ), or the like. In particular, when a fibrous conveyance object such as cloth is conveyed, the fuzzy fiber of the conveyance object gets stuck with the corner or burr of the cover  23 , which easily separate the cover  23 . When the cover  23  is separated, a foreign substance such as ink entering the head main body  21  through the separated area of the cover  23  may cause a failure or malfunction. 
     For example, when the ink enters inside through the separated area of the cover  23  and adheres to a current-carrying portion such as the flexible wiring member  50  (see  FIG.  4   ) inside the head main body  21 , a failure may occur due to current leakage. When the ink enters inside and adheres to the piezoelectric element  40  (see  FIG.  4   ) inside the head main body  21 , the subsequently solidified ink may avoid desirable driving of the piezoelectric element  40  and cause an ink discharge failure. 
     As described above, the separation of the cover  23  causes various disadvantages such as malfunction and failure. Therefore, the following measures are taken according to the present embodiment. 
       FIG.  7    is a schematic cross-sectional view of the liquid discharge head according to a first embodiment. As the basic structure of the liquid discharge head according to the present embodiment is substantially the same as the liquid discharge head illustrated in  FIGS.  3  and  4    above, the description will be omitted as appropriate for the already described part. 
     As illustrated in  FIG.  7   , the liquid discharge head  20  according to the present embodiment includes the nozzle plate  31  having the nozzle  30  (see  FIG.  4   ), the cover  23  serving as a nozzle protector that protects the nozzle  30 , the channel  32  including a channel including the supply-side individual channel  42  (see  FIG.  4   ), the collection-side individual channel  43  (see  FIG.  4   ), and the like, the common channel member  35  serving as a frame, the base  22  serving as a holder that holds the common channel member  35 , and the like. In  FIG.  7   , the base  22  also serves as a nozzle protector holder that holds the nozzle protector (cover  23 ). 
     In  FIG.  7   , the direction of an arrow Z indicates the liquid discharge direction in which the liquid (ink) is ejected through the nozzle of the nozzle plate  31 . Specifically, in  FIG.  7   , the nozzle surface  31   a , where the nozzle of the nozzle plate  31  is exposed, faces upward. 
     The cover  23  covers at least part of the nozzle surface  31   a  other than the nozzle. According to the present embodiment, the cover  23  covers the edge portion and its nearby portion of the nozzle surface  31   a.    
     Here, when the center side (the right side in  FIG.  7   ) of the nozzle surface  31   a  is “inner side” and the opposite side (the left side in  FIG.  7   ) is “outer side”, as illustrated in  FIG.  7   , a portion on the outer side of the cover  23  is bonded to the base  22  through an adhesive  54 . The base  22  is provided around the nozzle plate  31 , the channel  32 , and the common channel member  35 , and the portion on the outer side of the cover  23  is bonded to an end surface  220  of the base  22  facing in the liquid discharge direction Z. 
     As illustrated in  FIG.  7   , an upper portion of the base  22  includes a peripheral wall  22   b  arranged around the nozzle plate  31  and the channel  32 , and the base  22  serves as a nozzle protector holder that holds the cover  23  (nozzle protector). 
     The portion on the inner side of the cover  23  is bonded to the nozzle plate  31  and the channel  32  through an adhesive  55 . The channel  32  is bonded to the surface of the nozzle plate  31  (the lower surface of the nozzle plate  31  in  FIG.  7   ) on the opposite side of the nozzle surface  31   a , part of the channel  32  protrudes to the outer side from the edge portion of the nozzle plate  31 , and the cover  23  is bonded to the outwardly protruding portion of the channel  32  and the edge portion periphery of the nozzle plate  31 . 
     As described above, the portions on both sides, the inner side and outer side, of the cover  23  are bonded to the respective members through the adhesives  54  and  55 , and the space between each member and the cover  23  is sealed by the adhesives  54  and  55  to prevent the ink and other foreign matter from entering inside through the space. The cover  23  is bonded to the respective members through the adhesives  54  and  55 , and therefore even when the conveyed sheet hits the cover  23 , the cover  23  basically does not separate or fall off. 
     However, when the sheet repeatedly hits the outer edge face  230  of the cover  23  facing the outer side (the opposite side of the center side of the nozzle surface) or the fibrous sheet gets stuck with the edge (corner), burr formed on the edge of the outer edge face  230 , or the like, while the sheet is conveyed from the left side in  FIG.  7   , the cover  23  may separate. 
     Therefore, according to the present embodiment illustrated in  FIG.  7   , a highly rigid resin member  70  is provided to cover the outwardly facing the outer edge face  230  of the cover  23 , in other words, the outer edge face  230  (side surface) of the cover  23  on the side bonded to the base  22 . Hereinafter, the side surface may be also simply referred to as the “edge face  230 ” or “side surface” for convenience. 
     The resin member  70  is provided between the outer edge face  230  of the cover  23  and the end surface  220  of the base  22  facing in the liquid discharge direction Z. As illustrated in  FIG.  8   , the resin member  70  is provided over the entire outer edge face  230  (hatched area in  FIG.  8   ) of the cover  23 . 
     As described above, according to the present embodiment, as the highly rigid resin member  70  is provided over the entire outer edge face  230  of the cover  23 , the resin member  70  may prevent the sheet from coming into contact with and getting stuck with the outer edge face  230  of the cover  23 . As the direct contact of the sheet with the outer edge face  230  of the cover  23  may be prevented, the impact on the cover  23  may also be reduced. Accordingly, the separation of the cover  23  is unlikely to occur, and therefore the entry of a foreign matter such as ink through the separated area may be suppressed. As a result, the possibility of malfunction and failure is reduced, and the reliability is improved. 
     As illustrated in  FIG.  7   , according to the present embodiment, the resin member  70  does not protrude in the liquid discharge direction Z beyond the outer edge face  230  of the cover  23  and does not protrude to the outer side (the opposite side of the center side of the nozzle surface) from the end surface  220  of the base  22  facing in the liquid discharge direction Z. This may also prevent the sheet from getting stuck with the resin member  70 . The resin member  70  has an inclined surface  70   a  that is inclined toward the inner side (the center side of the nozzle surface or the side of the outer edge face  230  of the cover  23 ) so as to gradually protrude in the liquid discharge direction Z. 
     Therefore, when the sheet comes into contact with the resin member  70 , the sheet is guided along the inclined surface  70   a . As described above, according to the present embodiment, even when the sheet comes into contact with the resin member  70 , the sheet is guided without getting stuck, which may ensure stable and smooth sheet conveyance. As the resin member  70  has the inclined surface  70   a , the impact when the sheet hits the resin member  70  (the inclined surface  70   a ) is also reduced. Thus, the effect of impact on the cover  23  may also be reduced, and the separation of the cover  23  may be further prevented. 
     According to the present embodiment, the base  22  also has an inclined surface  22   a , as illustrated in  FIG.  7   . The inclined surface  22   a  is provided on a portion (an upper portion in  FIG.  7   ) of the base  22  adjacent to the resin member  70  and is formed to be continuous with the inclined surface  70   a  of the resin member  70 . The inclined surface  22   a  of the base  22  is inclined toward the inner side so as to gradually protrude in the liquid discharge direction Z, in the same manner as the inclined surface  70   a  of the resin member  70 . 
     According to the present embodiment, the inclined surfaces  22   a  and  70   a  of the base  22  and the resin member  70  have different inclination angles θ 1  and  02  with respect to the liquid discharge direction Z. Specifically, the inclination angle θ 1  of the inclined surface  70   a  of the resin member  70  is set to be larger than the inclination angle θ 2  of the inclined surface  22   a  of the base  22 . Accordingly, when the sheet comes into contact with the inclined surface  22   a  of the base  22 , the sheet is smoothly guided from the inclined surface  22   a  of the base  22  to the inclined surface  70   a  of the resin member  70 , which enables stable and smooth sheet conveyance. 
     A height t (see  FIG.  7   ) of the resin member  70  in the liquid discharge direction Z is preferably on the same level as the upper surface of the cover  23  in  FIG.  7   , but the height t may be lower than the upper surface of the cover  23  as long as the height t is higher than the lower surface of the cover  23 . That is, the resin member  70  may cover at least part of the outer edge face  230  of the cover  23 . Even when the resin member  70  covers part of the outer edge face  230  of the cover  23 , the contact of the sheet with the outer edge face  230  may be suppressed, and the possibility of separation of the cover  23  may be reduced. 
     The highly rigid resin member  70  preferably has a Young&#39;s modulus of 1 GPa or more in terms of adhesion and strength. Furthermore, the resin member  70  preferably has a Young&#39;s modulus of 3 GPa or more. The Young&#39;s modulus, also called the modulus of longitudinal elasticity, is the slope with respect to the stress during tensile test obtained using the following Equation (1). In Equation (1), are presents tensile stress, E represents the Young&#39;s modulus (modulus of longitudinal elasticity), and c represents strain. 
       (Equation 1) 
       σ= E×ε   (1)
 
     According to the present embodiment, as illustrated in  FIG.  8   , the resin member  70  is provided over the entire outer edge face  230  of the cover  23 , but when the contact area of the sheet with the outer edge face  230  is limited, the resin member  70  may also be provided at the contact area of the sheet (part of the outer edge face  230 ). For example, the resin member  70  may be provided, in the entire outer edge face  230  of the cover  23 , on a portion extending in the longitudinal direction (the direction of the arrow X in  FIG.  8   ) of the liquid discharge head  20  or a portion extending in the lateral direction (the direction of the arrow Y in  FIG.  8   ) of the liquid discharge head  20 . 
     In order to confirm the effect of the present embodiment, a comparative example illustrated in  FIG.  12    was created, and an evaluation test for the comparative example and the present embodiment was conducted. The comparative example has the same configuration as that of the present embodiment except that the highly rigid resin member  70  and the inclined surface  22   a  of the base  22  are not included. In this test, the liquid discharge head according to the comparative example or the present embodiment was mounted on the image forming apparatus and the sheet was conveyed, and it was checked whether the cover  23  was separated. 
     As a result, in the comparative example, the cover  23  of some of the liquid discharge heads was separated and failed, and part of the cover  23  of the other liquid discharge heads was not failed but separated. Conversely, according to the present embodiment, the cover  23  was not separated at all. Thus, with the configuration according to the present embodiment, it was confirmed that the separation of the cover  23  was effectively suppressed. 
     Next, an embodiment different from the above-described embodiment (the first embodiment) will be described. In the description below, the parts different from the above embodiment will be primarily described, and the description of the other parts will be omitted as appropriate as the other parts have basically the same configuration. 
       FIG.  9    is a schematic cross-sectional view of the liquid discharge head according to a second embodiment. 
     According to the second embodiment illustrated in  FIG.  9   , the base  22  (see  FIG.  7   ) is not included. Therefore, according to the present embodiment, the cover  23  is bonded to the common channel member  35  (frame) instead of the base  22 . Specifically, the common channel member  35  according to the present embodiment functions as a nozzle protector holder that is bonded to the cover  23  to hold the cover  23  (nozzle protector). 
     As illustrated in  FIG.  9   , a surface (upper surface in  FIG.  9   ) of the common channel member  35  is bonded to a surface (lower surface in  FIG.  9   ) of the channel  32  that is opposite to the surface (upper surface in  FIG.  9   ) of the channel  32  bonded to the nozzle plate  31 . Apart of the common channel member  35  includes a peripheral wall  35   b  disposed exterior of the nozzle plate  31  and the channel  32 . The cover  23  is bonded to a surface  350  of the peripheral wall  35   b  facing in the liquid discharge direction Z through an adhesive  56 . 
     According to the embodiment (the first embodiment) illustrated in  FIG.  7    above, an upper portion of the base  22  in  FIG.  7    in particular corresponds to a peripheral wall  22   b  arranged around the nozzle plate  31  and the channel  32 , and the base  22  corresponds to the nozzle protector holder that holds the cover  23 . 
     As described above, the second embodiment is different from the above-described embodiment in that the base  22  is not included and the cover  23  is bonded to the peripheral wall  35   b  of the common channel member  35 , but even with this configuration, the cover  23  may separate when the sheet comes into contact with the outer edge face  230  of the cover  23 . 
     Therefore, according to the present embodiment, as in the above-described embodiment, the highly rigid resin member  70  is provided to suppress the separation of the cover  23 . Specifically, according to the present embodiment, the resin member  70  is provided between the outer edge face  230  of the cover  23  and the surface  350  of the peripheral wall  35   b  facing in the liquid discharge direction Z. 
     Thus, according to the present embodiment, too, the contact of the sheet with the outer edge face  230  of the cover  23  may be prevented, and the separation of the cover  23  may be suppressed. The range where the resin member  70  is provided may be the entire outer edge face  230  of the cover  23  or part of the outer edge face  230 . 
     According to the present embodiment, too, the resin member  70  and the common channel member  35  (the peripheral wall  35   b ) have the inclined surface  70   a  and an inclined surface  35   a , respectively. The inclined surfaces  70   a  and  35   a  are inclined toward the inner side so as to gradually protrude in the liquid discharge direction Z, and the inclination angle θ 1  and an inclination angle θ 3  with respect to the liquid discharge direction Z are set to have the same relation as that between the inclination angles θ 1  and  02  of the resin member  70  and the base  22  according to the above-described embodiment. 
     That is, the inclination angle θ 1  of the inclined surface  70   a  of the resin member  70  is set to be larger than the inclination angle θ 3  of the inclined surface  35   a  of the common channel member  35 . Therefore, according to the present embodiment, too, the sheet may be smoothly guided from the inclined surface  35   a  of the common channel member  35  to the inclined surface  70   a  of the resin member  70 , and a reduction of the impact due to the contact of the sheet and stable and smooth sheet conveyance may be achieved. 
       FIG.  10    is a schematic cross-sectional view of the liquid discharge head according to a third embodiment. 
     According to the third embodiment illustrated in  FIG.  10   , the resin member  70  covering the outer edge face  230  of the cover  23  includes the adhesive  54  that bonds the cover  23  and the base  22 . When the rigidity of the adhesive  54  is high (the Young&#39;s modulus is 1 GPa or more), the adhesive  54  may be spread to the outer side beyond the cover  23 , and the spread portion may include the resin member  70  covering the outer edge face  230  of the cover  23 . The amount of the adhesive  54  to spread may be adjusted by changing at least one of the following: the adhesive application position, the amount of applied adhesive, and the pressure applied to bond the cover  23 . The inclined surface  70   a , which is the same as the one described above, may be formed in the resin member  70  by using methods such as forming the spread portion in a mold when the adhesive  54  is spread or cutting after the adhesive  54  is hardened. 
     The configuration according to the present embodiment is also applicable to the configuration without the base  22  as illustrated in  FIG.  9    as well as the configuration including the base  22  as illustrated in  FIG.  10   . 
     That is, part of the adhesive  56  bonding the common channel member  35  and the cover  23  illustrated in  FIG.  9    may include the resin member  70  covering the outer edge face  230  of the cover  23 . 
       FIG.  11    is a schematic cross-sectional view of the liquid discharge head according to a fourth embodiment. 
     According to the fourth embodiment illustrated in  FIG.  11   , the resin member  70  covering the outer edge face  230  of the cover  23  is integrally formed with the base  22 . When the base  22  is made of a resin material having high rigidity (Young&#39;s modulus of 1 GPa or more), part of the base  22  (at least part of the peripheral wall  22   b  illustrated in  FIG.  11   ) may cover the outer edge face  230  of the cover  23 . According to the present embodiment, too, as in each of the above embodiments, the contact of the sheet with the outer edge face  230  of the cover  23  may be suppressed, and thus the separation of the cover  23  is unlikely to occur. 
     The configuration according to the present embodiment is also applicable to the configuration without the base  22  as illustrated in  FIG.  9    as well as the configuration including the base  22  as illustrated in  FIG.  11   . 
     That is, part of the common channel member  35  (the peripheral wall  35   b ) illustrated in  FIG.  9    may include the resin member  70  covering the outer edge face  230  of the cover  23 . 
     The present embodiment has been described above, but the present embodiment is not limited to the above-described embodiment and may be modified in design as appropriate without departing from the content of the present embodiment. 
     According to the present embodiment, the “liquid discharge head” includes a functional component that discharges or ejects the liquid through the nozzle. The discharged liquid is not limited in particular and may be any liquid as long as the liquid has a viscosity or surface tension that allows discharge from the head, but the viscosity is preferably 30 mPa-s or less under the normal temperature and pressure or due to heating or cooling. More specifically, the liquid includes a solution, suspension, emulsion, or the like, containing a solvent such as water or organic solvent, colorant such as dye or pigment, function-adding material such as polymerizable compound, resin, and surfactant, biocompatible material such as DNA, amino acid, protein, or calcium, and edible material such as natural colorant, and the liquid may be used for application such as inkjet ink, surface treatment liquid, component such as an electronic device or light emitting device, liquid for forming an electronic circuit resist pattern, material liquid for three-dimensional modeling, etc. 
     The liquid discharge head may include one head main body as well as a plurality of head main bodies as in the above-described embodiments. 
     An energy generation source that discharges the liquid may include the one using a piezoelectric actuator (laminated piezoelectric element and thin-film piezoelectric element), a thermal actuator using an electricity-heat conversion element such as a heating resistor, an electrostatic actuator including a diaphragm and a counter electrode, etc. 
     According to the present embodiment, the “liquid discharge unit” includes the integration of a liquid discharge head and a functional part or mechanism and includes an assembly of pans related to liquid discharge. For example, the “liquid discharge unit” includes the one combining the liquid discharge head and at least one of the configurations of the following: a head tank, a carriage, a supply mechanism, a maintenance mechanism, a main scanning movement mechanism, and a liquid circulation device. 
     Here, the integration includes, for example, securing the liquid discharge head and the functional part or mechanism by fastening, bonding, engagement, etc., or holding the liquid discharge head and the functional part or mechanism such that either one moves relative to the other one. The liquid discharge head and the functional pan or mechanism may also be configured to be attachable to or detachable from each other. 
     For example, the liquid discharge head and the head tank may be integrated as a liquid discharge unit. Furthermore, the liquid discharge head and the head tank may be coupled to each other via a tube, or the like, to be integrated. Here, a unit including a filter may also be added between the head tank and the liquid discharge head of the liquid discharge unit. 
     The liquid discharge head and the carriage may be integrated as a liquid discharge unit. 
     The liquid discharge head is movably held by a guide member included in part of a scanning movement mechanism so that the liquid discharge head and the scanning movement mechanism may be integrated as a liquid discharge unit. The liquid discharge head, the carriage, and the main scanning movement mechanism may be integrated. 
     A cap member, which is a part of the maintenance mechanism, is secured to the carriage to which the liquid discharge head is attached, so that the liquid discharge head, the carriage, and the maintenance mechanism may be integrated as a liquid discharge unit. 
     A tube is coupled to the liquid discharge head to which the head tank or channel component is attached so that the liquid discharge head and the supply mechanism may be integrated as a liquid discharge unit. The liquid in a liquid storage source is supplied to the liquid discharge head via the tube. 
     The main scanning movement mechanism also includes a guide member alone. The supply mechanism also includes a tube alone or a loader alone. 
     The “liquid discharge apparatus” includes an apparatus that includes a liquid discharge head or a liquid discharge unit and drives the liquid discharge head to discharge the liquid. The liquid discharge apparatus also includes an apparatus that discharges the liquid into air or liquid as well as an apparatus that may discharge the liquid to an object to which the liquid may adhere. 
     The “liquid discharge apparatus” may also include units regarding feeding, conveyance, and sheet ejection of an object to which the liquid may adhere and also a pre-processing apparatus, a post-processing apparatus, etc. 
     Examples of the “liquid discharge apparatus” include an image forming apparatus that discharges the ink to form an image on a sheet and a stereoscopic modeling apparatus (three-dimensional modeling apparatus) that discharges a modeling liquid onto a powder layer, which is obtained by forming powers in a layer form, so as to produce a stereoscopic model (three-dimensional model). 
     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 arbitrarily images, such as arbitrarily patterns, or fabricate three-dimensional images. 
     The above-described “object to which the liquid may adhere” refers to a discharge object to which the liquid may adhere at least temporarily, such as the object to which the liquid is firmly fixed after adherence or the object which the liquid permeates after adherence. Specific examples include media such as sheets such as paper, recording paper, recording sheets, film, and cloth, electronic components such as electronic s and piezoelectric elements, powder layers (powdered layers), organ models, and inspection cells, and any object to which the liquid adheres unless otherwise specified. 
     The material of the above-described “object to which the liquid may adhere” may be any material as long as the liquid may adhere even temporarily, such as paper, yarns, fibers, woven fabrics, leathers, metals, plastics, glass, wood, and ceramics. 
     The “sheet” may also be a continuous sheet (e.g., roll paper) formed to be elongated or a sheet (e.g., cut paper) previously cut into a predetermined size. The present embodiment is also applicable to apparatuses that discharge the liquid to discharge objects other than sheets. 
     The “liquid discharge apparatus” includes an apparatus in which the liquid discharge head and the object to which the liquid may adhere are moved relative to each other, but is not limited thereto. Specific examples include a serial apparatus (see  FIG.  6   ) that moves the liquid discharge head and a line apparatus (see  FIG.  5   ) that does not move the liquid discharge head. 
     The “liquid discharge apparatus” further includes, for example, a treatment liquid application apparatus that discharges a treatment liquid onto paper to apply the treatment liquid to a surface of the paper for the purpose of modifying the surface of the paper, an ejection granulation apparatus that ejects a composition liquid, in which a raw material is dispersed in a solution, through a nozzle to granulate fine particles of the raw material. 
     [Aspect 1] 
     A liquid discharge head ( 20 ) includes: a nozzle plate ( 31 ) having: a nozzle surface ( 31   a ); and a nozzle ( 30 ) in the nozzle plate ( 31 ), a liquid being discharged from the nozzle ( 30 ) of the nozzle surface ( 31   a ) side in a liquid discharge direction; a nozzle protector ( 23 ) covering at least a part of the nozzle surface ( 31   a ) of the nozzle plate ( 31 ) other than the nozzle ( 30 ); a nozzle protector holder ( 22 ,  35 ) including a peripheral wall ( 22   b ,  35   b ) bonded to a peripheral end portion of the nozzle protector ( 23 ); and a resin member ( 70 ) between an edge face of the peripheral end portion of the nozzle protector ( 23 ) and an end surface ( 220 ) of the peripheral wall ( 35   b ) facing the nozzle protector ( 23 ). 
     [Aspect 2] 
     In the liquid discharge head according to Aspect 1, the resin member ( 70 ) includes an adhesive to bond the nozzle protector ( 23 ) and the nozzle protector holder ( 22 ,  35 ). 
     [Aspect 3] 
     The liquid discharge head according to any one of Aspect 1 to 2, further includes: a channel ( 32 ) having a first surface bonded to a bonding surface of the nozzle plate ( 31 ) opposite to the nozzle surface ( 31   a ), the channel ( 32 ) including a channel ( 41 ) communicating  1 ) with the nozzle ( 30 ). The nozzle protector holder ( 22 ,  35 ) includes a frame ( 35 ) bonded to a second surface of the channel ( 32 ) opposite to the first surface, 
     [Aspect 4] 
     The liquid discharge head according to any one of Aspect 1 to 2, further includes: a channel ( 32 ) having a first surface bonded to a bonding surface of the nozzle plate ( 31 ) opposite to the nozzle surface ( 31   a ), the channel ( 32 ) including a channel ( 41 ) communicating with the nozzle ( 30 ), and a frame ( 35 ) bonded to a second surface of the channel ( 32 ) opposite to the first surface. The nozzle protector holder ( 22 ,  35 ) includes a base ( 22 ) holding the frame ( 35 ). 
     [Aspect 5] 
     In the liquid discharge head according to any one of Aspect 1 to 5, the resin member ( 70 ) has a first inclined surface ( 70   a ) inclined toward the edge face of the peripheral end portion of the nozzle protector ( 23 ) 
     [Aspect 6] 
     In the liquid discharge head according to Aspect 5, the peripheral wall ( 35   b ) has a second inclined surface ( 22   a ) that is inclined toward the edge face of the peripheral end portion of the nozzle protector ( 23 ). 
     [Aspect 7] 
     In the liquid discharge head according to Aspect 6, a first inclination angle (θ 1 ) of the first inclined surface ( 70   a ) of the resin member ( 70 ) with respect to the liquid discharge direction is larger than a second inclination angle (θ 2 ) of the second inclined surface ( 22   a ) of the end surface ( 220 ) of the peripheral wall ( 22   b ) with respect to the liquid discharge direction. 
     [Aspect 8] 
     In the liquid discharge head according to any one of Aspect 1 to 7, the resin member ( 70 ) has a Young&#39;s modulus of 3 GPa or more. 
     [Aspect 9] 
     A liquid discharge apparatus includes the liquid discharge head according to any one of Aspect 1 to 8. 
     [Aspect 10] 
     A liquid discharge head ( 20 ) includes: a nozzle plate ( 31 ) having: a nozzle surface ( 31   a ); and a nozzle ( 30 ) in the nozzle plate ( 31 ), a liquid being discharged from the nozzle ( 30 ) of the nozzle surface ( 31   a ) side in a liquid discharge direction; a nozzle protector ( 23 ) covering at least a part of the nozzle surface ( 31   a ) of the nozzle plate ( 31 ) other than the nozzle ( 30 ); and a nozzle protector holder ( 22 ,  35 ) including a peripheral wall ( 35   b ) bonded to a peripheral end portion of the nozzle protector ( 23 ). At least apart of the peripheral wall ( 35   b ) is made of a resin member ( 70 ), and the peripheral wall ( 35   b ) covers the edge face of the peripheral end portion of the nozzle protector ( 23 ). 
     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.