Patent Publication Number: US-7905573-B2

Title: Liquid ejection head with nozzle plate deformed by heat and image forming apparatus including the liquid election head

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC §119 to Japanese Patent Application No. 2007-160858, filed on Jun. 19, 2007, and Japanese Patent Application No. 2008-105277, filed on Apr. 15, 2008, the entire contents of which are incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     This disclosure relates to a liquid ejection head and an image forming apparatus, and in particular to a liquid ejection head ejecting liquid drops and an image forming apparatus employing the liquid ejection head. 
     2. Discussion of the Background Art 
     An image forming apparatus, such a printer, a facsimile, a copier, a complex machine configured by combining these devices, etc., sometimes employs a liquid ejection device that includes a printing head having a liquid ejection head for ejecting and adhering liquid drops onto a medium, such as a paper, a string, a texture, a towel, a leather, a metal, a plastic, a glass, woods, ceramics, etc., while conveying the printing sheet to form an image. 
     The image formation includes not only a meaningful image, such as a character, a figure, etc., but also a meaningless image, such as a pattern, etc. The liquid is not limited to printing liquid or ink, but includes every type of liquid as far it is capable of executing image formation. The liquid ejection device generally ejects liquid from a liquid ejection head. 
     As one example of such a liquid ejection head employed in an image forming includes a heater in a nozzle plate to eject liquid drops from the nozzle while deforming the nozzle plate using a difference in heat expansion has been known as discussed in Japanese Patent Application Laid Open No. 2001-105590. 
     Various types of a liquid ejection head that deforms a nozzle plate including a flexible film by heat are described in the Japanese Patent Application Laid Open Nos. 2002-359981 and 2004-160650 as well as the Japanese Patent Registration No. 2827544. 
     There is a type that changes a fluidity resistance by connecting a vibration plate and a piezoelectric element to a bottom of the fluidity resistance flow path communicated with one end of the pressurizing chamber as described in the Japanese Patent Application Laid Open No. 2001-063047. 
     Since a liquid ejection head generally ejects liquid drops from a nozzle by pressurizing a liquid chamber or a flow path, pressure preferably does not leak from the liquid chamber when the pressure in the liquid chamber is to be efficiently increased and is applied to the liquid drops to be ejected. Thus, a liquid resistance section is arranged in the flow path that supplies liquid to the liquid chamber. In this point of view, the Japanese Patent Application Laid Open No. 2001-063047 employs a device capable of increasing the fluidity resistance when liquid drops are ejected. 
     However, these prior arts are still insufficient. 
     BRIEF SUMMARY 
     In an aspect of this disclosure, there is provided a liquid ejection head that includes a nozzle plate having a nozzle for ejecting liquid drops, an actuator for deforming a nozzle plate portion surrounding the nozzle, and a flow path member opposing the nozzle plate and forming a flow path for guiding liquid to the nozzle. 
     In another aspect, a fluidity resistance path is formed in the flow path between the nozzle plate portion and a portion of the flow path member opposing the nozzle plate portion. A fluidity resistance of the fluidity resistance path is changed by deforming the nozzle plate portion. 
     In another aspect, the flow path member includes at least one convex opposing either the nozzle or the nozzle plate portion in the fluidity resistance path. 
     In yet another aspect, the flow path member includes an inlet opposing the nozzle across the convex and configured to take in the liquid to the flow path. 
     In yet another aspect, the flow path member includes at least one concave opposing the nozzle plate portion in the fluidity resistance path. 
     In yet another aspect, the liquid ejection head includes a nozzle plate having a nozzle that ejects liquid drops, a deformable member including a wall opposing the nozzle, which guides liquid to the nozzle, and an actuator that deforms the deformable member. A holding member opposing the nozzle via the deformable member is provided to form a flow path guiding the liquid to the nozzle. A fluidity resistance path is formed in the flow path between a nozzle plate portion surrounding the nozzle and a surface of the deformable member opposing the nozzle plate portion. A fluidity resistance of the fluidity resistance path is changed by deforming the deformable member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       A more complete appreciation of the aforementioned and other aspects, features and advantages will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a cross sectional view illustrating an exemplary liquid ejection head according to a first embodiment of the present invention; 
         FIG. 2  is a plan view schematically illustrating the exemplary liquid ejection head of  FIG. 1 ; 
         FIG. 3  is a cross sectional view illustrating an exemplary operation of the liquid ejection head of  FIG. 1 ; 
         FIG. 4  is a cross sectional view illustrating an exemplary liquid ejection head according to a modification of the first embodiment of the present invention; 
         FIG. 5  is a plan view schematically illustrating the exemplary liquid ejection head of  FIG. 4 ; 
         FIG. 6  is a cross sectional view illustrating an exemplary liquid ejection head according to a second embodiment of the present invention; 
         FIG. 7  schematically illustrates an exemplary image forming apparatus according to the present invention; 
         FIG. 8  illustrates an exemplary wiping operation executed in the image forming apparatus of  FIG. 7 ; 
         FIG. 9  is a plan view schematically illustrating an exemplary liquid ejection head according to a third embodiment of the present invention; 
         FIG. 10  is a cross sectional view schematically illustrating the liquid ejection head of  FIG. 9 ; 
         FIG. 11  is a cross sectional view schematically illustrating an exemplary liquid ejection head according to a fourth embodiment of the present invention. 
         FIG. 12  is a cross sectional view schematically illustrating an exemplary liquid ejection head according to a fifth embodiment of the present invention; 
         FIG. 13  is a cross sectional view illustrating one example of a vibration plate member included in the head of  FIG. 12 ; 
         FIGS. 14A and 14B  are cross sectional views collectively illustrating an exemplary operation of the head shown in  FIG. 12 ; 
         FIGS. 15A to 15E  are cross sectional views collectively illustrating an exemplary manufacturing process for manufacturing the vibration plate member of  FIG. 12 ; 
         FIG. 16  is a cross sectional view schematically illustrating an exemplary liquid ejection head according to a sixth embodiment of the present invention; 
         FIG. 17  is a cross sectional view illustrating an exemplary operation of the head shown in  FIG. 16 ; and 
         FIG. 18  is a cross sectional view schematically illustrating an exemplary liquid ejection head according to a seventh embodiment of the present invention. 
     
    
    
     PREFERRED EMBODIMENTS OF THE PRESENT INVENTION 
     Referring now to the drawing, wherein like reference numerals designate identical or corresponding parts throughout several views, in particular, in  FIGS. 1 and 2 , an exemplary liquid ejection head according to the present invention is described. As shown, the liquid ejection head is formed by connecting a nozzle plate  1  to a flow path member  2  (e.g. a flow path substrate)  2 . 
     A nozzle  3  is formed on the nozzle plate  1  to eject liquid drops. The nozzle plate  1  includes three layers. Specifically, an upper layer  11  is made of material having a large thermal expansion coefficient, such as Ni—Cr of 16×10E-6/° C. An inner layer  12  is made of material having a small thermal expansion coefficient, such as Cr of 8×10E-6/° C. A heater layer  4  is provided as an intermediate layer  4  between the layers  11  and  12  to serve as an actuator device. The intermediate layer  4  has a circular planner shape and surrounds the nozzle  3 . The intermediate layer forms a bimetallic structure. Thus, an electrode  5  is connected to the heater layer  4  so as to supply power. 
     The flow path member  2  includes an ink supply inlet  21  and an ink supply path  22 . The flow path member  2  includes a convex part  23  opposing the nozzle  3  and a surrounding area  6  of the nozzle  3  (herein after referred to as a nozzle surrounding section  6 ). Between a surface  24  of the convex part  23  and the nozzle surrounding section  6 , a fluidity resistance path  7  having a larger fluidity resistance than that of the ink supply path  22  or another flowpath section of the ink supply inlet  21  are formed. 
     As shown by a void arrow in  FIG. 1 , liquid (ink) is supplied from the ink supply inlet  21  to the fluidity resistance path  7  via the image supply path  22  in such a liquid ejection head, thereby the nozzle  3  is fulfilled with the ink. In this state, by turning on the heat layer  4 , the nozzle plate  1  having the above-mentioned bimetallic structure is heated up due to heat generation of the heat layer  4 . Thus, the nozzle surrounding section  6  of the nozzle plate  1  is bent and deforms toward the opposing surface  24 . Accordingly, the ink in the nozzle  3  receives pressure and is ejected from the nozzle  3 . 
     At this moment, owing to approach of the nozzle surrounding section  6  toward the opposing surface  24 , a cross sectional area of the opening of the fluidity resistance path  7  decreases, and the resistance value of the liquid in the fluidity resistance path  7  increases. As a result, an amount of the ink flowing from the nozzle  3  to the ink supply path  22  decreases. 
     Thus, pressure caused at the nozzle  3  is hardly conveyed to the image supply path  22 , and is dedicatedly used as energy for ejecting the ink. As a result, ejection efficiency is significantly improved while low voltage drive can be obtained saving the power. 
     Thus, a fluidity resistance is changed by a simple construction and thereby capable of efficiently ejecting dink drops. 
     Now, a modification of the first embodiment of the liquid ejection head is described with reference to  FIGS. 4 and 5 . As shown, the ink supply inlet  21  is arranged opposing the nozzle  3  over the convex part  23 , and supplies ink to the fluidity resistance path  7  from the ink path  26 . Thus, a lateral width of the liquid ejection head becomes smaller, and thereby the cost is reduced. 
     Now, a second embodiment of the liquid ejection head is described with reference to  FIG. 6 . As shown, the fluidity resistance path  7  is formed between the nozzle surrounding section  6  and the opposing surface  24 . A concave part  25  is formed at a section of the opposing surface  24  to serve as an ink pool. Thus, a capacity of ink increases in the section, and thereby fixation of ink in the nozzle  3  due to ink drying can be suppressed. 
     Now, a driving operation of the liquid ejection head is described. As mentioned above, the liquid ejection head ejects ink by turning on the heater layer  4  while deforming the nozzle surrounding section  6 . At that moment, by ejecting liquid drops while disengaging the nozzle surrounding section  6  with the opposing surface  24 , a deformation amount of the nozzle plate  1  (i.e., the nozzle surrounding section  6 ) and accordingly a size of the ink drop can be changed in accordance with an amount of electricity supplied to the heater layer  4 . As a result, a multi bit and high quality image having an excellent gray scalability can be printed. 
     By ejecting the liquid drops while engaging the nozzle surrounding section  6  with the opposing surface  24 , the liquid drops can be constantly ejected and a high quality image can be obtained. Because, the amount of deformation of the nozzle surrounding section  6  is substantially constant. 
     Further, prescribed power is initially supplied to the heater layer  4  to change a size of the fluidity resistance path  7  to have a prescribed fluidity resistance not to eject ink drops, and then larger power can be supplied to eject the ink drops. Thus, a high quality image having an excellent gray scalability can be obtained, because a size of the liquid drops can be previously changed. 
     Now, an exemplary image forming apparatus including a liquid ejection head is described with reference to  FIG. 7 . The image forming apparatus includes an image formation section  202  in an apparatus body  201 . A sheet-feeding tray  204  capable of stacking a plurality of printing sheets  203  is arranged at a lower section of the apparatus body  201 . One of the printing sheets  203  fed from the sheet feeding tray  204  is taken in and receives printing of a prescribed image at the image formation section  202  while being conveyed by a conveyance mechanism  205 . Then, the printing sheet  203  is ejected onto a sheet ejection tray  206  attached to a side of the apparatus body  201 . 
     When a duplex unit  207  is attached to the apparatus body to execute duplex printing, the printing sheet  203  is reversely conveyed after one side printing is completed by the conveyance mechanism  205  and is taken in by the duplex unit  207 . Then, the printing sheet is reversed to enable the other side to get ready to receive printing and is further launched into the conveyance mechanism  205  again. The printing sheet  203  is then ejected onto the printing sheet ejection tray  206  after the other side receives the printing. 
     The image formation section  202  includes four printing heads  211   k  to  211   y  of a full-line type for ejecting ink of black, cyan, magenta, and yellow mono-colors (K, C, M, and Y), respectively. Herein after, the four printing heads  211   k  to  211   y  are referred to as printing heads  211  when mono-color does not matter. Each of the printing heads  211  is attached with its nozzle surface facing downward, which forms a nozzle for ejecting liquid drops. 
     Four maintenance recovery mechanisms  212   k  to  212   y  are provided corresponding to the respective printing heads  211 . Herein after, the four maintenance recovery mechanisms  212   k  to  212   y  are referred to as a maintenance recovery mechanism  212  when mono-color does not matter. When a performance maintenance operation, such as a purge process, a wiping process, etc., is executed, the printing head  211  and the maintenance recovery mechanism  212  are relatively moved so that four capping members serving as the maintenance recovery mechanism  212  can oppose the nozzle surface of the printing head  211 . 
     As mentioned heretofore, the printing heads  211  are arranged to eject yellow to black colors in turn from the upstream side in the sheet conveyance direction. However, arrangement and number of colors are not limited thereto. One or more number of line type heads each including a plurality of nozzle lines can be employed for ejecting liquid drops of respective colors. An ink cartridge for supplying the head with ink can be integral with or separate from the head. Further, a line head can be formed by arranging straight lines of heads displaced from each other. 
     The printing sheets  203  in the sheet feeding tray  204  are separated by a separation pad, not shown, in cooperation with a sheet feeding roller  221  having a half moon shape one by one, and are is launched into the apparatus body  201 . The printing sheet  203  is transferred into a gap between the registration roller  225  and the conveyance belt  233  along a guide surface  223   a  of the conveyance guide member  223 . Then, the printing sheet  203  is transferred onto the conveyance belt  233  of the conveyance mechanism  205  via the guide member  226  at a prescribed time. 
     On the conveyance guide member  223 , a guide surface  223   b  is formed so as to guide a printing sheet  203  launched from the duplex unit  207 . Further arranged therein is a guide member  227  to guide the printing sheet  203  returned from a conveyance mechanism  205  to the duplex unit  207  when a duplex printing is executed. 
     The conveyance mechanism  205  includes an endless conveyance belt  233  wound around a conveyance roller  231  as a driving roller and a driven roller  232 , a discharge roller  234  for discharging the conveyance belt  233 , and a platen member  235  for maintaining the conveyance belt  233  to be flat at a section opposing the image formation section  235 . Also included are a pressure applying roller  236  for depressing the printing sheet  203  toward the conveyance belt  233  and the conveyance roller  231 , and a cleaning roller made of spongy member for removing printing liquid, such as ink adhering to the conveyance belt  233  or the like. 
     On the downstream side of the conveyance mechanism  205 , an ejection roller  238  and a spur  239  are provided to launch a printing sheet  203  with an image onto the ejection tray  206 . 
     In such an image forming apparatus, the conveyance belt  233  travels and circulates in a direction as shown by an arrow, and is charged by contacting the discharge roller  334  in a positive polarity, because a voltage of a high potential is applied to the discharge roller  334 . Specifically, the discharge roller  234  with a charge voltage discharges the conveyance belt  233  at a prescribed interval while a polarity thereof is switched at the prescribed interval. 
     When a printing sheet  203  is fed onto the conveyance belt  233  with the charge of the high potential, the inside of the printing sheet  203  becomes a polarity-separated condition. Thus, electrode having a reverse polarity to that on the conveyance belt  233  is induced on the surface of the printing sheet  203  contacting the conveyance belt  233 , and the electrode on the conveyance belt  233  and that on the printing sheet  203  electro-statically pull each other. Thus, the printing sheet  203  is electro-statically attracted to the conveyance belt  233 . As a result, bent and concavity and convexity on the printing sheet are corrected when the printing sheet is intensely attracted to the conveyance belt  233 , thereby highly flat surface can be formed. 
     By circulating the conveyance belt  233  and thereby conveying the printing sheet  203  while ejecting liquid drops from the printing head  21 , a prescribed printing image is formed on the printing sheet  203 . Then, the printing sheet  203  with the printing image is ejected onto the sheet ejection tray  206  by the sheet ejection roller  238 . 
     As a result, an image can be formed at high speed highly improving efficiency of ejecting liquid drops. 
     Now, an exemplary maintenance recovery operation for a printing head of the image forming apparatus is described with reference to  FIG. 8 . A wiping member  251  is provided on a scanning member  252  as a maintenance recovery mechanism  212  for wiping the surface  1   a  of the nozzle of the printing head  211 . When a wiping operation is executed, prescribed power is supplied to the heater layer of the printing head  211  not to eject liquid drops and temperature of the surface of the nozzle plate  1  increases. Then, the nozzle surface  1   a  of the printing head  211  is wiped by moving and scanning the wiping member  251 . 
     Since the temperature of the nozzle plate surface (i.e. the ejection side surface) increases due to the power supply to the heater serving as an actuator, adhesion ink and plastic are soften, and thereby sticking force decreases. Accordingly, the nozzle plate surface can be easily cleaned by means of the wiping member. As a result, a bias to the wiping member can be decreased, and accordingly, a waterproof layer applied to the nozzle surface or the like hardly wears, thereby a durability of the head is improved. Further, ink can be replenished while preliminary applying prescribed heat to the nozzle plate not to eject drops, similarly. 
     Now, another exemplary liquid ejection head of a third embodiment according to the present invention is described with reference to  FIGS. 9 and 10 . The liquid ejection head includes a nozzle plate  101  including a nozzle  111  for ejecting liquid drops, a vibration plate  102  serving as a displace member arranged opposing the nozzle plate  101  so as to form a wall of a flow path  112 , which guides the liquid drops to the nozzle  111 , a heater layer  124  serving as an actuator for bending and deforming the vibration plate  102  with heat, and a holding member  103  arranged opposing the nozzle plate  101  over the vibration plate  102  to form a flow path  113 , which guides the liquid to the surface of the vibration plate opposite to the nozzle plate  101 . Further, a fluidity resistance path  107  having a larger fluidity resistance than the flow path  112  is formed between the surrounding section on the nozzle  111  of the nozzle plate  101  and a section of the vibration plate  102  opposing the surrounding section  106 . 
     The vibration plate  102  includes a three-layer construction similar to the above-mentioned nozzle plate  1 . Specifically, a layer  121  made of material having a relatively low thermal expansion coefficient is arranged on the side of the nozzle  101 . A layer  122  made of material having a relatively high thermal expansion coefficient is arranged opposing the nozzle  101 . And, a heater layer  124  serving as an actuator is arranged between the layers  121  and  122 . Thus, a bimetallic construction is formed. An electrode  125  is connected to the heater layer  124 . 
     In the holding member  103 , an ink supply inlet  131  and a flow path  113  are formed. In the flow path member  103 , a limit section  133  is provided to limit a deformation of the vibration plate  102  opposing the nozzle  111 . Further, in the vibration plate  102 , a passage  114  connecting the flow paths  112  and  113  to each other are arranged. 
     In the liquid ejection head with such a construction, liquid (e.g. ink) is supplied from the ink supply inlet  131  to the fluidity resistance path  107  via the flow paths  113  and  112 , and the passage  114 . Thus, the nozzle  111  is fulfilled with the ink. Then, by supplying power to the heater layer  124  and causing the heat layer  124  to generate heat, the vibration plate  102  is heated. Thus, a central section of the vibration plate  102  deforms toward the nozzle  111  and ink within the nozzle  111  is pressurized, thereby liquid drops are ejected from the nozzle  111 . 
     Due to bending of the vibration plate  102  toward the nozzle surrounding section  106 , an area of the opening of the fluidity resistance path  107  decreases while a fluidity resistance of the fluidity resistance path  107  increases. Thus, an amount of the ink flowing from the nozzle  111  to the flow path  112  is reduced. Accordingly, since pressure caused by deformation of the vibration plate member is almost spent as ink ejection energy, ejection efficiency is significantly improved. Further, low voltage driving is achieved while suppressing consumption of the power. 
     Since the vibration plate  102  including the heater layer  124  as an actuator device is arranged in the liquid, heat transmission from the heater layer  124  is hardly accumulated in the holding member  103  and the nozzle plate  101 . As a result, driving can be steady and continuous. 
     Now, an exemplary liquid ejection head of a fourth embodiment is described with reference to  FIG. 11 . A liquid ejection head has a similar configuration to that in the third embodiment. However, a liquid chamber  142  facing to the nozzle  111  is formed by means of the nozzle plate  101  and the vibration plate  102  employing a passage  107  on the vibration plate  102  as a fluidity resistance section. Thus, by applying pressure to the ink in the liquid chamber  142  by means of deformation of the vibration plate  102  due to the heat, the liquid drops is ejected from the nozzle  111 . 
     Also in this configuration, since the vibration plate  102  including the heater layer  124  is arranged in the ink as liquid, heat transmission from the heater layer  124  is hardly accumulated in the holding member  103  and the nozzle plate  101 , thereby capable of steadily and continuously driving the liquid ejection head. 
     Any of the liquid ejection head described in these third and fourth embodiment can be built-in in an image forming apparatus. 
     Now, a fifth embodiment of an exemplary liquid ejection head according to the present invention is described with reference to  FIG. 12 . The liquid ejection head includes a fluid path member  300 , a nozzle plate  301  having a nozzle  311  for ejecting liquid drops, a vibration plate member  302  that opposes the nozzle plate  301  and forms walls of a pressurizing chamber  312  communicated with the nozzle  311  and a fluidity path  313  for supplying liquid to the pressurizing chamber  312  as a displacing member, and a heat layer  304  serving as an actuator for bending and deforming the vibration plate member  302  with heart. The liquid ejection head also includes a stopper member  305  disposed opposing the nozzle plate  301  (or a pressuring chamber  312 ) via the vibration plate member  302  and is contacted by the vibration plate member  302  when the actuator device deformed the vibration plate member  302 . 
     Further, a convex section  306  is formed on the nozzle plate  301  around the nozzle  311  and thereby forming the pressuring chamber  312 . Between the convex section  306  and the portion of the vibration plate member  302  opposing the convex section  306 , a fluidity resistance path  307  having larger fluidity resistance than the fluidity path  313  that communicated with the pressurizing chamber  312  is formed. A supply inlet, not shown, supplies liquid to the fluidity path  313 . 
     As shown in  FIG. 13 , the vibration plate member  302  includes a vibration plate layer  321  having a poly-silicone layer or the like, a heater layer  304 , an insulation layer  322 , an anti-ink layer  323  or the like and is initially bent on the side of the anti-ink layer  323 . Since the periphery of the vibration plate member  302  is secured, the central section (i.e., a section opposing the nozzle  311 ) is bent toward the stopper member  305 . 
     Since the vibration plate member  302  extends in parallel to its plane when the heater layer  304  is supplied with power, and the vibration plate member  302  is deformed and contacts the stopper member  305  as shown in  FIG. 14A  due to the initial bent toward the anti-ink layer  323 . However, since the periphery is secured when the vibration plate member  302  extends, the vibration plate member  302  is deformed toward the nozzle  311  and pressurizes the liquid in the pressurizing chamber  312  as shown in  FIG. 14B , thereby liquid drops are ejected from the nozzle  311 . 
     At this moment, since the vibration plate member  302  is bent toward the convex section  306 , a cross sectional area of the opening of the fluidity resistance path  307  decreases, and a fluidity resistance on the fluidity resistance path  307  increases, ink flowing into the pressurizing chamber  312  from the nozzle  311  decreases. As a result, the bending force is mainly used for ink ejection energy, and accordingly, ejection efficiency is significantly improved while saving a head driving voltage and power. 
     Now, one example of a manufacturing process for manufacturing the above-mentioned vibration plate member  302  is described with reference to  FIGS. 15A to 15E . As shown in  FIG. 15A , a silicone nitride film (Si 3 N 4 )  402  having a thickness of about 0.2 micrometer is initially coated onto a silicone substrate  401  using a LPCVD method. Then, as shown in  FIG. 15B , a metal film (e.g. a heater layer)  403  having a thickness of about 0.2 micrometer is coated onto the silicone nitride film  402  using a spatter method. A patterning process is performed to create a prescribed shape using a lithography etching method. Then, as shown in  FIG. 15C , a poly-silicone layer  404  having a thickness of about 0.5 micrometer is coated onto the metal film  403  using the LPCVD method. Then, as shown in  FIG. 15D , a poly-silicone layer  405  having a thickness of about 0.2 micrometer is coated onto the poly-silicone layer  404  using the LPCVD method. Then, as shown in  FIG. 15E , an etching process is applied to the silicone substrate  401 , and a concave section  406  is formed to provide the pressurizing chamber  312  and the fluidity path  313 . Since the silicon nitride film  402  and the metal film  403  serve as tension stress films, while the poly-silicone layer  404  and the silicone oxide film  405  serve as compression stress films, the vibration plate member  302  is bent as a whole on the side of the silicone oxide film  405 . 
     Now, a sixth embodiment of an exemplary liquid ejection head is described with reference to  FIG. 16 . The difference from the liquid ejection head of the fifth embodiment is that a convex section  306  is provided on the side of the vibration plate member  302  to form a fluidity resistance path  307  having a larger fluidity resistance than the fluidity path  313  communicated with the pressurizing chamber  312  between the periphery section of the nozzle  311  and a surface of the vibration plate member  302  opposing the periphery section. 
     Specifically, the vibration plate member  302  is deformed as shown in  FIG. 17 , when the heater layer  304  is supplied with power. 
     Now, a seventh embodiment of an exemplary liquid ejection head is described with reference to  FIG. 18 . The difference from the sixth embodiment is that plural stoppers  305  are arranged between the central from the sixth embodiment and outer peripheral sections on the vibration plate  302 . As similar to the fifth and sixth embodiments, the vibration plate member  302  is deformed on the side of the nozzle  311  after contacting the stoppers  305  and  306 , thereby liquid drops is ejected. 
     The above-mentioned various embodiments of the present invention can be applied to a facsimile, a copier, a multifunction machine having functions of a printer, the facsimile and the copier beside the printer. Further, the invention is also applied to an image forming apparatus that ejects liquid other than the ink, such as resist, DNA sample used in a medical field, or the like. Numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise that as specifically described herein.