Abstract:
A liquid ejection head including: a flow-channel forming substrate having a pressure generating chamber which communicates with a liquid supply channel which communicates with one end of the pressure generating chamber in terms of a first direction so as to have a first length for supplying liquid to the pressure generating chamber; and a pressure generating unit that causes the change in pressure in the pressure generating chamber, wherein the liquid supply channel is formed by narrowing the width of the pressure generating chamber in a second direction substantially perpendicular to the first direction so as to have a second length shorter than the first length, a stepped surface is formed between the side surface of the pressure generating chamber in the second direction and the side surface of the liquid supply channel in the second direction, and wherein a bridge is provided at a corner defined by the stepped surface, the side surface of the pressure generating chamber in the second direction on the stepped surface side, and one of the surfaces of the pressure generating chamber in a third direction which is orthogonal to the first direction and the second direction of the flow-channel forming substrate for bridging the corner.

Description:
[0001]    The entire disclosure of Japanese Patent Application No. 2006-211464, filed Aug. 2, 2006 expressly incorporated by reference herein. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a liquid ejection head and a liquid ejection apparatus for injecting liquid and, more specifically, to an ink jet type recording head and an ink jet type recording apparatus for discharging ink as the liquid. 
         [0004]    2. Related Art 
         [0005]    Various types of ink jet type recording heads, which correspond to a liquid ejection head generally used in printers, facsimile machines, copying machines and so on are known according to the mechanism for discharging ink drops. For example, there are a type in which ink drops are discharged from nozzle openings by employing a diaphragm as part of a pressure generating chamber which communicates with the nozzle openings and expanding and contracting the capacity of the pressure generating chamber by deforming the diaphragm by displacing a piezoelectric element, and a type in which ink drops are discharged from nozzle openings by changing the capacity of a pressure generating chamber by deforming a diaphragm using electrostatic force. 
         [0006]    There is an ink jet type recording head in which a piezoelectric element is provided on one side of a flow-channel forming substrate which is provided with the pressure generating chamber in communication with the nozzle openings in an area which opposes the pressure generating chamber via the diaphragm. The flow-channel forming substrate is formed with an ink supply channel which communicates with one end side of the pressure generating chamber in terms of the longitudinal direction by reducing the width of the pressure generating chamber in the short side direction thereof and an inclined surface formed by inclining a stepped surface between the pressure generating chamber and the ink supply channel in the direction of the thickness of the flow-channel forming substrate (for example, see JP-A-2005-153243 (pp. 7-10, FIG. 2). 
         [0007]    However, even though the stepped surface between the pressure generating chamber and the ink supply channel is formed into the inclined surface as disclosed in JP-A-2005-153243, there remains a problem such that air bubbles entering ink supplied from the side of the ink supply channel may stay at a corner defined by the stepped surface and a side surface of the pressure generating chamber, and when the air bubbles are grown up, the interior capacity of the pressure generating chamber is reduced, so that the ink discharging property may be adversely affected. 
         [0008]    There is also proposed a configuration in which the corner of the ink supply channel for supplying the ink to the pressure generating chamber is formed into a curved surface along a crystal axis (for example, see JP-A-7-178909 (p. 3, p. 5, FIG. 8 and FIG. 16). 
         [0009]    However, with the configuration in JP-A-7-178909, there remains a problem such that air bubbles entering the ink flowing through the ink supply channel cannot be prevented from staying therein. 
       SUMMARY 
       [0010]    An advantage of some aspects of the invention is to provide a liquid ejection head and a liquid ejection apparatus in which the liquid injecting property is improved by preventing air bubbles from staying in a flow channel. 
         [0011]    A first aspect of the invention is a liquid ejection head including: a flow-channel forming substrate having a pressure generating chamber which communicates with nozzle openings for injecting liquid and a liquid supply channel which communicates with one end of the pressure generating chamber in terms of a first direction so as to have a first length for supplying liquid to the pressure generating chamber; and pressure generating means for causing the change in pressure in the pressure generating chamber, wherein the liquid supply channel is formed by narrowing the width of the pressure generating chamber in a second direction substantially perpendicular to the first direction so as to have a second length shorter than the first length, a stepped surface is formed between the side surface of the pressure generating chamber in the second direction and the side surface of the liquid supply channel in the second direction, and wherein a bridge is provided at a corner defined by the stepped surface, the side surface of the pressure generating chamber in the second direction on the stepped surface side, and one of the surfaces of the pressure generating chamber in a third direction which is orthogonal to the first direction and the second direction of the flow-channel forming substrate for bridging the corner and is comprised of the same material as the flow-channel forming substrate. 
         [0012]    In this configuration, with the provision of the bridge, air bubbles entering liquid supplied from the liquid supply channel to the pressure generating chamber are prevented from staying at the corner of the pressure generating chamber on the liquid supply channel side, and hence the interior capacity of the pressure generating chamber is prevented from changing due to the stayed air bubbles which are grown up, so that the liquid injecting property may be improved. 
         [0013]    Preferably, the surface of the bridge is an inclined surface inclined with respect to the stepped surface, the side surface of the pressure generating chamber in the second direction on the stepped surface side, and one of the surfaces of the pressure generating chamber in the third direction of the flow-channel forming substrate. 
         [0014]    In this configuration, the air babbles are prevented from staying at the corner defined by the bridge, the stepped surface, the side surface of the pressure generating chamber in second direction on the stepped surface side, and the one of the surfaces of the pressure generating chamber in the third direction of the flow-channel forming substrate. 
         [0015]    Preferably, the flow-channel forming substrate is provided with a communication channel having a width larger than that of the liquid supply channel in a second direction at the end of the liquid supply channel on the opposite side from the pressure generating chamber, a stepped surface is provided between the communicating portion and the liquid supply channel, the bridge is provided at a corner defined by the stepped surface, the inner surface of the communication channel in the second direction on the stepped surface side, and one of the surfaces of the communication channel in the third direction of the flow-channel forming substrate for bridging the corner. 
         [0016]    In this configuration, with the provision of the bridge at the corner of the communication channel on the liquid supply channel side, air bubbles are prevented from staying at the corner of the communication channel on the liquid supply channel side and the internal capacity of the communication channel from changing due to the stayed air bubbles, so that the liquid injecting property may be improved. 
         [0017]    Preferably, the pressure generating means includes a piezoelectric element provided on the flow-channel forming substrate on the one of the surfaces thereof via a diaphragm, and the one of the surfaces of the pressure generating chamber in the flow-channel forming substrate is defined by the diaphragm. 
         [0018]    In this configuration, a liquid ejection head superior in the liquid injecting property is achieved by the employment of the piezoelectric element. 
         [0019]    Preferably, the stepped surface is formed vertically with respect to the one of the surfaces of the flow-channel forming substrate. 
         [0020]    In this configuration, even with the stepped surface which is liable to cause the air bubbles to stay at the corner of the pressure generating chamber on the stepped surface side, air bubbles may be prevented from staying by the bridge. 
         [0021]    Preferably, the stepped surface is formed of an inclined surface inclined with respect to the third direction of the flow-channel forming substrate. 
         [0022]    In this configuration, even with the stepped surface which hinders easy stay of air bubbles at the corner of the pressure generating chamber on the stepped surface side, the stay of the air bubbles may be reliably prevented by the bridge. 
         [0023]    According to a second aspect of the invention, there is provided a liquid ejection apparatus having the liquid ejection head according the first aspect of the invention. 
         [0024]    In this configuration, the liquid ejection apparatus in which the liquid injecting property is improved is achieved. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
           [0026]      FIG. 1  is an exploded perspective view of a recording head according to a first embodiment. 
           [0027]      FIG. 2A  is a plan view of  FIG. 1 . 
           [0028]      FIG. 2B  is a cross-sectional view of  FIG. 1 . 
           [0029]      FIG. 3  is an exploded perspective view of the recording head according to a second embodiment. 
           [0030]      FIG. 4A  is a plan view of  FIG. 3 . 
           [0031]      FIG. 4B  is a cross-sectional view of  FIG. 3 . 
           [0032]      FIG. 5  is an exploded perspective view of the recording head according to a third embodiment. 
           [0033]      FIG. 6  is a schematic drawing showing an example of an ink jet type recording apparatus according to an embodiment. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0034]    Embodiments of the invention will be described in detail below. 
       First Embodiment 
       [0035]      FIG. 1  is an exploded perspective view of an ink jet type recording head as an example of a liquid ejection head according to a first embodiment of the invention, and  FIG. 2A  is a plan view of  FIG. 1 , and  FIG. 2B  is a cross-sectional view taken along the line A-A′ in  FIG. 1 . As shown in the drawing, a flow-channel forming substrate  10  is formed of a silicone monocrystal substrate of a crystal plane azimuth (110) in the first embodiment, and is formed in advance with a resilient film  50  being formed of silicon dioxide and having a thickness of 0.5 to 2 μm on one surface thereof by thermal oxidation. 
         [0036]    The flow-channel forming substrate  10  includes a plurality of pressure generating chambers  12  partitioned by a plurality of partitioning walls  11  arranged in parallel in the direction of the width (short side direction) by anisotropic etching from the side of the other surface. 
         [0037]    The flow-channel forming substrate  10  includes ink supply channels  14  as liquid supply channels and communication channels  15  partitioned by the partitioning walls  11  at one end sides of the pressure generating chambers  12  in terms of the longitudinal direction. Formed at one end of the communication channels  15  is a communicating portion  13  which constitutes part of a reservoir  100  which corresponds to a common ink chamber (liquid chamber) of the respective pressure generating chambers  12  in communication with the reservoir portion  31  of a protective substrate  30 , described later. That is, in the first embodiment, the flow-channel forming substrate  10  is provided with the pressure generating chambers  12 , the communicating portion  13 , the ink supply channels  14 , and the communication channels  15  as liquid channels having the pressure generating chambers  12 . 
         [0038]    The ink supply channels  14  communicate with the one end sides of the pressure generating chambers  12  in terms of the longitudinal direction and each have a width smaller than that of the pressure generating chamber  12 . That is, the ink supply channels  14  are formed by narrowing the flow channels of the pressure generating chamber  12  sides between the reservoir  100  and the respective pressure generating chambers  12  in the widthwise direction. The reason why the flow channels of the ink supply channels  14  are narrowed in the widthwise direction is because the ink supply channels  14  and other flow channel systems can be formed easily at once without using a mask which requires consideration of the thickness of the silicon monocrystal substrate which constitutes the flow-channel forming substrate  10  when forming the flow channel system including the pressure generating chambers  12 , the communicating portion  13 , and the communication channels  15  and the ink supply channels  14  simultaneously by etching. 
         [0039]    The respective communication channels  15  are formed by extending the partitioning walls  11  on both sides of the pressure generating chambers  12  in terms of the widthwise direction toward the communicating portion  13  side for partitioning spaces between the ink supply channels  14  and the communicating portion  13 . The communication channels  15  each are formed to have a width larger than that of the ink supply channel  14 . In the first embodiment, the communication channels  15  are formed to have the same width as that of the pressure generating chambers  12 . 
         [0040]    Provided between the pressure generating chambers  12  and the ink supply channels  14  are stepped surfaces  16  formed by the provision of the ink supply channels  14 . The stepped surfaces  16  are formed vertically with respect to one surface of the flow-channel forming substrate  10 , and are inclined with respect to the short side direction of the pressure generating chambers  12 . The longitudinal length of the pressure generating chambers  12  is defined by these stepped surfaces  16 . 
         [0041]    Provided at corners defined by the stepped surfaces  16 , one side surfaces of the pressure generating chambers  12  on the side of the stepped surfaces  16  extending in the short side direction and the resilient film  50  which corresponds to one surfaces of the pressure generating chambers  12  in the direction of the thickness of the flow-channel forming substrate  10  are bridges  17 . 
         [0042]    The bridges  17  are provided to have a smaller height than the depth of the pressure generating chambers  12 , and the surfaces thereof are inclined with respect to the stepped surfaces  16 , the one side surfaces of the pressure generating chambers  12 , and one side surfaces of the resilient film  50 . The surfaces of the bridges  17  may be formed into a flat surface, a curved surface, or a combination of the flat surface and the curved surface. 
         [0043]    The bridges  17  may be formed, for example, by leaving parts of the flow-channel forming substrate  10  unetched by adjusting the etching conditions such as the concentration or the temperature of etching liquid when forming the pressure generating chambers  12 , the communicating portion  13 , the ink supply channels  14 , and the communication channels  15  by applying anisotropic etching (wet etching) on the flow-channel forming substrate  10 . That is, the bridges  17  are formed of parts of the flow-channel forming substrate  10 . The bridges  17  may be formed of a material separate from the flow-channel forming substrate  10 , for example, of resin or the like, as a matter of course. 
         [0044]    In the first embodiment, the stepped surfaces  16  are formed also between the communication channels  15  and the ink supply channels  14 , and the bridges  17  are formed also at corners defined by the stepped surfaces  16 , the one side surfaces of the communication channels  15  in terms of the short side direction and the resilient film  50 . 
         [0045]    In this manner, with the ink supply channels  14  formed by reducing the widths of the communication channels  15  and the pressure generating chambers  12  and with the provision of the bridges  17  at the corners, when the ink from the communicating portion  13  is supplied to the pressure generating chambers  12  via the communication channels  15  and the ink supply channels  14 , air bubbles entering the ink are prevented from staying at the corners and hence the interior capacities of the pressure generating chambers  12  and the communication channels  15  are prevented from changing by the stayed air bubbles which are grown up, so that the ink discharging properties may be improved. 
         [0046]    Secured on the flow-channel forming substrate  10  on the opening surface side thereof is a nozzle plate  20  formed with nozzle openings  21  which communicate with portions near the end portions of the respective pressure generating chambers  12  on the opposite sides of the ink supply channels  14  with adhesive agent or a thermally welded film or the like. The nozzle plate  20  is formed, for example, of glass ceramics, a silicon monocrystal substrate, and stainless steel (SUS), or the like. 
         [0047]    On the other hand, on the surface of the flow-channel forming substrate  10  opposite from the nozzle plate  20  is formed with the resilient film  50  having a thickness, for example, of about 1.0 μm, as described above, and an insulating film  55  having a thickness, for example, of about 0.4 μm is formed on the resilient film  50 . In addition, a lower electrode film  60  having a thickness, for example, of about 0.2 μm, a piezoelectric substance layer  70  having a thickness, for example, of about 1.0 μm, and an upper electrode film  80  having a thickness, for example, of about 0.05 μm are laminated on the insulating film  55  through a process described later, so that a piezoelectric element  300  is configured. The piezoelectric element  300  in this specification represents a portion including the lower electrode film  60 , the piezoelectric substance layer  70 , and the upper electrode film  80 . In general, one electrode of the piezoelectric element  300  is used as a common electrode, and the other electrode and the piezoelectric substance layer  70  are formed on each pressure generating chamber  12  by patterning. In this specification, portions configured with one of the patterned electrodes and the piezoelectric substance layer  70  and distorted piezoelectrically by the application of voltage to the both electrodes are referred to as a piezoelectric substance active portion  320 . In the first embodiment, the lower electrode film  60  serves as the common electrode of the piezoelectric elements  300 , and the upper electrode films  80  serve as individual electrode of the piezoelectric elements  300 . However, these functions may be reversed without any problem depending on the convenience of a drive circuit or wiring. In any cases, the piezoelectric substance active portions  320  are formed respectively on the pressure generating chambers  12 . In this specification, a combination of the piezoelectric elements  300  and a diaphragm which is displaced by driving the piezoelectric elements  300  is referred to as an actuator device. That is, in the first embodiment, the actuator device including the diaphragm and the piezoelectric elements  300  as pressure generating means which causes the pressure change in ink stored in the pressure generating chambers  12  is provided. Although the resilient film  50 , the insulating film  55 , and the lower electrode film  60  serve as the diaphragms in the example shown above, it is also possible to provide only the lower electrode film  60  without providing the resilient film  50  and the insulating film  55 , and use the lower electrode film  60  as the diaphragm. 
         [0048]    Lead electrodes  90  formed of gold (Au) or the like and extended to the ink supply channels  14  side of the flow-channel forming substrate  10  are connected respectively to the upper electrode films  80  of the respective piezoelectric elements  300 . Voltage is selectively applied to the respective piezoelectric elements  300  via the lead electrodes  90 . 
         [0049]    A protective substrate  30  formed with a reservoir portion  31  at an area opposing the communicating portion  13  is joined onto the flow-channel forming substrate  10  formed with the piezoelectric elements  300  via an adhesive agent  35 . The reservoir portion  31  is communicated with the communicating portion  13  of the flow-channel forming substrate  10  as described above, and configures the reservoir  100  which corresponds to a common ink chamber of the respective pressure generating chambers  12 . 
         [0050]    The protective substrate  30  is provided with a piezoelectric element holding portion  32  having a space to a degree which does not impair the movement of the piezoelectric elements  300  in the area opposing the piezoelectric element  300 . The piezoelectric element holding portion  32  must simply has a space to the extent which does not impair the movement of the piezoelectric element  300 , and the space may either be sealed or unsealed. 
         [0051]    An area of the protective substrate  30  between the piezoelectric element holding portion  32  and the reservoir portion  31  is provided with a through hole  33  so as to penetrate the protective substrate in the direction of thickness, and part of the lower electrode film  60  and the distal end portions of the lead electrodes  90  are exposed in the through hole  33 . 
         [0052]    Mounted on the protective substrate  30  is a drive circuit  200  for driving the piezoelectric elements  300 . The drive circuit  200  may be, for example, a circuit board, a semiconductor integrated circuit (IC), or the like. The drive circuit  200  and the lead electrodes  90  are electrically connected via a connecting wire  210  formed of a conductive wire such as a bonding wire. 
         [0053]    The protective substrate  30  is preferably formed of a material having substantially the same coefficient of thermal expansion as the flow-channel forming substrate  10 , such as glass or ceramic material. In the first embodiment, it is formed of a silicon monocrystal substrate of the plane azimuth (110), which is the same material as the flow-channel forming substrate  10 . 
         [0054]    Joined on the protective substrate  30  is a compliance substrate  40  including a sealing film  41  and a fixed plate  42 . The sealing film  41  in this specification is formed of a flexible material having low rigidity (for example, polyphenylene sulfide (PPS) film of a thickness of 6 μm) and one of the surfaces of the reservoir portion  31  is sealed by the sealing film  41 . The fixed plate  42  is formed of a hard material such as metal (for example, stainless steel (SUS) of a thickness of 30 μm or the like). The area of the fixed plate  42  opposing the reservoir  100  is formed into an opening portion  43  which is completely removed in the direction of the thickness, and hence the one of the surfaces of the reservoir  100  is sealed only by the flexible sealing film  41 . 
         [0055]    With the ink jet type recording head in the first embodiment, ink is taken from external ink supply means, not shown, ink is filled into the interior from the reservoir  100  to the nozzle openings  21 , voltage is applied between the lower electrode films  60  and the upper electrode films  80  which correspond to the pressure generating chambers  12  respectively according to the recording signals from the drive circuit  200  to cause the resilient film  50 , the insulating film  55 , the lower electrode film  60 , and the piezoelectric substance layer  70  to warp, so that the pressure in the respective pressure generating chambers  12  is increased and hence the ink drops are injected from the nozzle openings  21 . 
       Second Embodiment 
       [0056]      FIG. 3  is an exploded perspective view of an ink jet type recording head showing an example of a liquid ejection head according to a second embodiment of the invention, and  FIG. 4A  is a plan view of  FIG. 3  and  FIG. 4B  is a cross-sectional view taken along the line B-B′ in  FIG. 3 . The similar members to those in the first embodiment described above are represented by the same reference numerals, and the overlapped description is omitted. 
         [0057]    As shown in the drawing, a flow-channel forming substrate  10 A which constitutes the ink jet type recording head includes the pressure generating chambers  12 , the ink supply channels  14 , the communication channels  15 , and the communicating portion  13 . Stepped surfaces  16 A between the pressure generating chambers  12  and the ink supply channels  14 , and between the ink supply channels  14  and the communication channels  15  are inclined with respect to the direction of depth of the pressure generating chambers  12  (the direction of thickness of the flow-channel forming substrate  10 A) and is formed so as to be inclined with respect to the direction of the short side of the pressure generating chambers  12 . 
         [0058]    Bridges  17 A are provided at corners defined by the stepped surfaces  16 A on the pressure generating chambers  12  side, one side surface of the pressure generating chamber  12  in the short side direction on the stepped surfaces  16 A side, and one of the surfaces of the resilient film  50  which defines one of the surfaces in the direction of depth of the pressure generating chambers  12 . 
         [0059]    Furthermore, the bridges  17 A are also provided at corners defined by the stepped surfaces  16 A on the communication channels  15  side, one side surface of the communication channels  15  on the stepped surfaces  16 A in the direction of the short side, and one of the surface of the resilient film  50  which defines one of the surfaces of the communication channels  15  in the depth direction. 
         [0060]    In this configuration as well, when the ink from the communicating portion  13  is supplied to the pressure generating chambers  12  via the communication channels  15  and the ink supply channels  14 A, air bubbles entering the ink are prevented from staying at the corners and hence the interior capacities of the pressure generating chambers  12  and the communication channels  15  are prevented from changing by the stayed air bubbles which are grown up, so that the ink discharging properties may be improved. 
       Third Embodiment 
       [0061]      FIG. 5  is an exploded perspective view of an ink jet type recording head showing an example of a liquid ejection head according to a third embodiment of the invention. The similar members to those in the above-described embodiments are represented by the same reference numerals, and the overlapped description is omitted. 
         [0062]    As shown in  FIG. 5 , a flow-channel forming substrate  10 B which constitutes the ink jet type recording head includes the pressure generating chambers  12 , the ink supply channels  14 , and the communicating portion  13 , ink from the communicating portion  13  is supplied to the pressure generating chambers  12  via the ink supply channels  14 . 
         [0063]    The stepped surface  16  between the pressure generating chambers  12  and the ink supply channels  14  is formed to be vertical to the one of the surfaces of the flow-channel forming substrate  10 B as in the first embodiment described above, and is inclined with respect to the direction of the short side of the pressure generating chambers  12 . 
         [0064]    The bridges  17  are provided at corners defined by the stepped surfaces  16 , the one side surfaces of the pressure generating chambers  12  in the short side direction on the stepped surfaces  16  side, and one of the surfaces of the resilient film  50  which defined one of the surfaces of the pressure generating chambers  12  in the depth direction. 
         [0065]    That is, in the third embodiment, the communication channel  15  is not provided on the flow-channel forming substrate  10 B, and the bridges  17  are provided only on the pressure generating chambers  12  side. 
         [0066]    In this configuration as well, as in the first embodiment described above, when the ink from the communicating portion  13  is supplied to the pressure generating chambers  12  via the ink supply channels  14 , air bubbles entering the ink are prevented from staying at the corners and hence the interior capacities of the pressure generating chambers  12  and the communication channels  15  are prevented from changing by the stayed air bubbles which are grown up, so that the ink discharging properties may be improved. 
       Other Embodiment 
       [0067]    Although some embodiments of the invention have been described thus far, the basic configuration of the invention is not limited thereto. For example, the ink supply channels  14  are configured by narrowing the width of the flow channels from one side in the first to third embodiments described above. However, the invention is not limited thereto and, for example, the ink supply channels may be narrowed from both sides thereof. When the width of the flow channels may be formed by narrowing the width from the both sides, stepped surfaces are formed on the both sides, and hence the bridges may be formed at corners defined by the stepped surfaces on both sides. 
         [0068]    The silicon monocrystal substrate having the crystal plane azimuth (110) has been exemplified as the flow-channel forming substrate  10  in the first to third embodiments described above. However, the invention is not limited thereto and, for example, the silicon monocrystal substrate having the crystal plane azimuth (100) may be used and, alternatively, the material as a SOI substrate and glass or the like may be used. 
         [0069]    The ink jet type recording head in the respective embodiments shown above, part of the recording head unit having the ink flow channels which communicate with an ink cartridge or the like is configured and is mounted to the ink jet type recording apparatus.  FIG. 6  is a schematic drawing showing an example of the ink jet type recording apparatus. 
         [0070]    As shown in  FIG. 6 , recording head units  1 A and  1 B having the ink jet type recording head are detachably provided with cartridges  2 A and  2 B which constitute ink supply means, and a carriage  3  having the recording head units  1 A and  1 B mounted thereon is provided on a carriage shaft  5  mounted to an apparatus body  4  so as to be movable in the axial direction. The recording head units  1 A and  1 B are adapted to discharge black ink composition and color ink composition, respectively. 
         [0071]    Then, by transmitting drive force of a drive motor  6  to the carriage  3  via a plurality of gears and a timing belt  7 , not shown, the carriage  3  having the recording head units  1 A and  1 B mounted thereon is moved along the carriage shaft  5 . On the other hand, a platen  8  is provided on the apparatus body  4  along the carriage shaft  5 , so that a recording sheet S as a recording medium such as paper fed by a paper feed roller or the like, not shown, is wound around the platen  8  and is carried. 
         [0072]    In the first to third embodiments described above, the actuator device having the piezoelectric elements is used as the pressure generating means. However, it is also possible to arrange the diaphragm and electrodes at a predetermined distance and employ a so-called electrostatic actuator which controls oscillation of the diaphragm by electrostatic force as the pressure generating means. Although the ink jet type recording head has been exemplified as an example of the liquid ejection head, the invention may be applied widely to general liquid ejection heads, and may be applied to a method of manufacturing liquid ejection heads for injecting liquid other than ink as a matter of course. Other liquid ejection heads include, for example, various recording heads used in an image recording apparatus such as printers, color material injection heads used for manufacturing color filters such as liquid crystal display or the like, electrode material injection heads used for forming electrodes for organic EL displays, FED (field emission display), and so on, and biological organic substance injection heads used for manufacturing bio chips.