Abstract:
An ink jet recording head includes a recording element substrate provided on one side thereof with a plurality of ejection outlet arrays each including a plurality of ejection outlets for ejecting recording liquid and provided on the other side thereof with a plurality of supply ports for supplying the recording liquid to the ejection outlet arrays, respectively; and a supporting member for supporting the recording element substrate by connecting with the other side of the recording element substrate. The supporting member has a plurality of supply passages for supplying the recording liquid to respective supply ports. The supporting member is provided with a partition between adjacent ones of the liquid passages, and at least one side of the partition is provided with pits and projections arranged alternately along a longitudinal direction of the partition.

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to an ink jet recording head for recording on various recording media, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, lumber, ceramic, etc. 
     An ink jet recording method is a recording method which records an image on recording medium by creating droplets of recording liquid, and adhering the droplets of recording liquid to the recording medium. This recording method is extremely small in recording noise, and also, is capable of recording at a high speed. Further, a recording head which uses this recording method can be made extremely small in size. Thus, an ink jet recording method may be said to be advantageous as a recording method for a color recording head, and also, a small recording head. 
       FIG. 7  is a perspective view of a typical ink jet recording head. It shows the general structure of the recording head. The ink jet recording head  1100  shown in  FIG. 7  has a recording chip  1101 , an electric wiring board  1102 , a recording chip supporting member  1150 , and a recording liquid container  1109 . The recording chip  1101  is for ejecting droplets of recording liquid. The recording chip  1101  and electric wiring board  1102  are attached to the recording liquid container  1109 . 
       FIGS. 8(A) and 8(B)  are plan views of the outward (front) and inward (rear) surfaces, respectively, of the recording chip  1101  shown in  FIG. 7 , and show the general structure of the recording chip  1101 .  FIG. 9  is a plan view of the recording chip supporting surface of the supporting member, to which the recording chip  1101  shown in  FIG. 7  is adhered. 
     The recording chip  1101  is attached to the recording chip supporting surface  1115  of the supporting member  1150  by its inward (rear) surface, with the use of adhesive  1104 . The supporting member  1150  is solidly attached to the recording liquid container  1109  after the bonding of the recording chip  1101  to the recording chip supporting member  1150 . The recording liquid in the recording liquid container  1109  is supplied to the main recording liquid passages  1105  of the recording chip  1101  through the holes  1106  of the supporting member  1150 . Then, the recording liquid is ejecting out of the recording chip  1101 , and adheres to recording medium; an image is formed on the recording medium. More specifically, in the recording chip  1101 , the recording liquid is heated by the heating elements (unshown), with which the recording chip  1101  is provided. As a result, the recording liquid is jetted out of the recording liquid ejecting orifices of the recording chip  1101 , by the pressured generated by the heating of the recording liquid. 
     In recent years, demand has been increasing for recording apparatuses capable of printing a high quality image at a high speed. One of the known solutions for increasing an ink jet recording apparatus in recording speed is to provide the ink jet recording apparatus with a larger recording chip, that is, a recording chip having a larger number of ink ejecting orifices. One of the known solutions for improving an ink jet recording apparatus in image quality is to provide the recording apparatus with a recording chip which is higher in ink ejecting orifice density. However, the cost for manufacturing a recording chip which is larger in size, and/or higher in ink ejecting orifices, is substantially higher than that for an ordinary recording chip. Thus, in order to realize a recording chip which is faster in record speed and higher in image quality, it is necessary to more precisely and reliably bond the abovementioned supporting member and recording chip to each other. One of the technologies for more precisely and reliably bonding the supporting member and recording chip to each other is disclosed in Japanese Laid-open Patent Application 2002-154209. In the case of the recording chip disclosed in this patent application, its main and branch passages for recording liquid were reduced in pitch to yield this recording chip which is higher in ink ejecting orifice density. 
     In a case where a supporting member, having the holes as the recording liquid passages, is manufactured by molding, the normal accuracy of the recording chip adhesion area of the supporting member is roughly 50 μm. Here, “accuracy of the recording chip adhesion area” means the difference in height between the highest and lowest points of the recording chip adhesion area of the supporting member. Unless the recording chip adhesion area of the supporting member is perfectly flat, there occur gaps between the chip adhesion area of the supporting member and the recording chip, and/or the recording chip becomes tilted relative to the recording chip adhesion area, as the recording chip is placed on the recording chip adhesion area of the supporting member. In order to prevent these problems, adhesive is used to attach the recording chip to the supporting member to compensate the unevenness of the recording chip adhesion area of the supporting member. As for the method for applying adhesive to the recording chip adhesion area of the supporting member, generally, the adhesive is directly exuded onto the recording chip adhesion area from the needle of an adhesive dispenser. 
     However, the following problem occurred during the manufacturing of a recording chip designed to be significantly narrower in the interval between the adjacent main recording liquid passages  1105  than conventional recording chips, in order to further reduce recording chip cost. That is, narrowing of the interval between the adjacent two main recording liquid passages  1105  of the recording chip required modifying the interval (pitch) of the recording liquid passages (holes) of the supporting member  1150 . Further, in order to ensure that the recording chip is supplied with a satisfactory amount of recording liquid, each of the recording liquid passages (hole) cannot be reduced in the size of its opening in terms of its cross-section. Therefore, the only solution is to reduce in thickness the partitioning wall between the adjacent two main recording liquid passages (holes) of the supporting member  1150 . In other words, each partitioning wall of the recording chip supporting member  1150  has to be no more than 0.5 mm, for example, in thickness, which is extremely thin. In a case where the partitioning wall of the recording chip supporting member  1150  is no more than 0.5 mm in thickness, it is impossible to reliably apply adhesive to the partitioning wall, using a conventional method for applying adhesive to bond the recording chip to the supporting member; as adhesive was applied, the adhesive flowed into the recording liquid passages of the supporting member. The analysis of this problem revealed that in order to properly apply adhesive to each partitioning wall, the adhesive application needle has be positioned significantly more precisely relative to each partitioning wall in terms of both the X and Y directions in  FIG. 9  than it used to be. The conventional needle positioning accuracy is in a range of ±100 μm. However, it became evident from the abovementioned analysis that in a case where the recording liquid passage pitch of the supporting member is as small as described above, the needle positioning accuracy must be in a range of ±25 μm. 
     The adhesive application needle positioning accuracy can be improved by reducing the needle in diameter. However, the reduction in the needle diameter increases the needle in the flow resistance between the needle and the adhesive, which results in decrease in the amount by which the adhesive can be exuded per unit length of time from the needle. In other words, the reduction in the diameter of the adhesive application needle results in an increase in the length of the time for applying the adhesive to each supporting member, which in turn results in the reduction in the productivity of a recording head factory, and also, increase in recording head cost. Thus, this solution, that is, simply reducing in diameter the adhesive application needle, is not desirable. 
     SUMMARY OF THE INVENTION 
     Thus, the primary object of the present invention is to provide an ink jet recording head which is significantly higher in the pitch of the main recording liquid passages than any of conventional ink jet recording heads, and yet, is as reliable as, or more reliable than any of conventional ink jet recording heads, in terms of the bond between its recording chip and recording chip supporting member, and also, is as good as, or superior to, any of conventional ink jet recording heads, in terms of manufacturing efficiency. 
     According to an aspect of the present invention, there is provided an ink jet recording head comprising a recording element substrate provided on one side thereof with a plurality of ejection outlet arrays each including a plurality of ejection outlets for ejecting recording liquid and provided on the other side thereof with a plurality of supply ports for supplying the recording liquid to the ejection outlet arrays, respectively; and a supporting member for supporting said recording element substrate by connecting with said other side of said recording element substrate, said supporting member has a plurality of supply passages for supplying the recording liquid to respective supply ports, wherein said supporting member is provided with a partition between adjacent ones of said liquid passages, and at least one side of said partition is provided with pits and projections arranged alternately along a longitudinal direction of said partition. 
     The present invention makes it possible to provide an ink jet recording head which is significantly higher in the pitch of the main recording liquid passages than any of conventional ink jet recording heads, and yet, is as reliable as, or more reliable than any of conventional ink jet recording heads, in terms of the bond between its recording chip and recording chip supporting member, and also, is as good as, or superior to, any of conventional ink jet recording heads, in terms of manufacturing efficiency. 
     These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially exploded perspective view of the ink jet recording head in the first preferred embodiment of the present invention. 
         FIGS. 2(   a ) and  2 ( b ) are plan and enlarged views of the recording chip supporting surface of the recording chip supporting member, to which the recording chip of the ink jet recording head shown in  FIG. 1  is attached. 
         FIG. 3  is a schematic plan view of the recording chip supporting member, shown in  FIG. 2 , after the coating of the recording chip supporting member with adhesive across its recording chip bonding area. 
         FIGS. 4(   a ) and  4 ( b ) are sectional views of the recording chip supporting portion of the recording chip supporting member, at planes C-C and C′-C′, respectively, in  FIG. 3 . 
         FIG. 5  is a schematic plan view of the recording chip supporting surface of the recording chip supporting member, which shows the area of the recording chip supporting surface, which is to be coated with the adhesive, and the directions in which the adhesive is to be applied with an adhesive dispenser. 
         FIGS. 6(   a ) and  6 ( b ) are plan and enlarged views of the recording chip supporting surface of the recording chip supporting member of the ink jet recording head in the second preferred embodiment of the present invention, to which the recording chip is to be bonded. 
         FIG. 7  is perspective views of the typical ink jet recording head as seen from the two different angles, which show the general structure of the ink jet recording apparatus. 
         FIGS. 8(A) and 8(B)  are plan views of the front (outward) and rear (inward) surfaces, respectively, of the recording chip shown in  FIG. 7 , which show the general structure of the recording chip. 
         FIG. 9  is a plan view of the recording chip supporting surface of the recording chip supporting member, to which the recording chip shown in  FIG. 7  is bonded. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, the preferred embodiments of the present invention will be described with reference to the appended drawings. 
     Embodiment 1 
       FIG. 1  is a partially exploded perspective view of the ink jet recording head in the first preferred embodiment of the present invention. 
     The ink jet recording head  100  has a recording liquid container  109 , which is made up of a container proper and a lid (unshown in  FIG. 1 ) for covering the container proper. The recording liquid chamber, that is, the spaces formed by the container proper and lid, is filled with yellow (Y), magenta (M), and cyan (C) color inks, one for one. Further, each recording liquid storage space contains an absorbent member (unshown) for retaining recording liquid. The ink jet recording head  100  has also a recording chip supporting member  150  (which hereafter will be referred to simply as supporting member), to which the recording chip  101  for ejecting recording liquid is bonded. The supporting member  150  is attached to the bottom of the recording liquid container  109 . The recording chip  101  has: heat generating elements, branch recording liquid passages, recording liquid ejecting orifices, and main recording liquid passages, etc., which are formed prior to the attachment of the recording chip  101  to the supporting member  150  (none of them are shown in drawing). More specifically, the recording chip  101  is provided with: multiple liquid ejecting orifices, and multiple main recording liquid passages (openings). The liquid ejecting orifices are open in multiple straight columns, on one of the primary surfaces of the recording chip  101 , whereas the main recording liquid passages are open in parallel on the other primary surface of the recording chip  101 . Incidentally, the structure of the recording chip  101  in this embodiment is the same as that described with reference to  FIG. 8 , and therefore, will not be described in detail here. 
     The recording chip  101  is bonded to the electrical wiring board  102 . The electrical wiring board  102  is provided with a device hole  120  for recording chip  101 , and electrical terminals  121 , with which the wiring board  101  is connected to the electrodes of the recording chip  100 . The electrical wiring board  102  is also provided with external signal input terminals  122 , through which control signals are received by the recording chip  101  from the main assembly of the recording apparatus. The external signal input terminals  122  are in connection with the electrical terminals  121 , through the wiring formed of copper foil. 
       FIG. 2(   a ) is a plan view of the recording chip supporting surface of the supporting member, to which the recording chip of the ink jet recording head shown in  FIG. 1  is bonded.  FIG. 2(   b ) is an enlarged view of a part of the recording chip bonding area of one of the partitioning walls of the supporting member  150 . 
     The supporting member  150  for supporting the recording chip  101  is molded of a resinous substance, which in this embodiment is a mixture of a resin and the glass filler which is mixed by 35% to yield a supporting member superior in rigidity. The supporting member  150  has multiple recording liquid passages for supplying the main recording liquid passages of the recording chip  101  with the recording liquids stored in the recording liquid chambers, one for one. There is a partition wall  108  between the adjacent two recording liquid passages  106 , in order to prevent recording liquid of one color from mixing with recording liquid of another color. 
     Each vertical surface (surface perpendicular to recording chip supporting surface) of each partitioning wall is provided with multiple protrusions  108   b , which are arranged in the lengthwise direction of the partitioning wall  108  with equal intervals, creating multiple recesses  108   a  with equal intervals. In this embodiment, these protrusions  108   b  (recesses  108   a ) are shaped so that their edges are straight. Further, the thickness w 1  of the partition wall  108 , that is, the thickness corresponding to the recess  108   a , is 0.4 mm, and the thickness w 2  of the partitioning wall  108 , that is, the thickness corresponding to the protrusion  108   b , is 0.7 mm. Further, the measurement (thickness) of the protrusion  108   b  in terms of the lengthwise direction of the partitioning wall  108  is 0.4 mm, and so is the measurement of the recess  108   a . The pitch of the protrusions  108   b  is 0.8 mm. Further, the measurement (depth) of the recess  108   a  in terms of the direction perpendicular to the surface of the paper on which  FIG. 2  is drawn, is 0.4 mm. Further, in this specification of the present invention, the referential plane for the recess  108   a  and protrusion  108   b  is the plane which is parallel to the vertical walls of the partitioning wall  108  and coincides with the mid point between the deepest point of the recess  108   a  and highest point of the protrusion  108   b  in terms of the direction X of the partitioning wall  108   a.    
     Next, referring to  FIGS. 3-5 , the steps for applying adhesive  104  to the recording chip supporting area  115  of the supporting member  150  with the use of an adhesive dispenser will be described.  FIG. 3  is a schematic plan view of the recording chip supporting area of the supporting member  150  after the coating of the recording chip supporting area (shown in  FIG. 2 ) of the supporting member  150  with the adhesive.  FIGS. 4(   a ) and  4 ( b ) are sectional views of the recording chip supporting area of the recording chip supporting member, at planes C-C and C′-C′, respectively, in  FIG. 3 .  FIG. 5  is a schematic plan view of the recording chip supporting surface of the recording chip supporting member, which shows the area of the recording chip supporting surface, which is to be coated with the adhesive, and the directions in which the adhesive is to be applied with an adhesive dispenser. 
     As for the adhesive choice, any adhesive may be selected from among the adhesives which can remain in the shape in which they are applied, after they are applied to the partitioning wall  108 . The adhesive used in this embodiment is such an adhesive that is 14,000 mPa×s in viscosity, and 1.8 in thixo-ratio. The needle of the dispenser was 0.4 mm in diameter. 
     The adhesive  104  is applied to the recording chip supporting area  115  of the supporting member  150  and each of the partitioning walls  108 , from the needle (unshown) of the dispenser. Referring to  FIG. 5 , the direction indicated by an arrow mark Y is the direction in which the needle is moved relative to the partitioning wall  108  when the adhesive  104  is coated on the partitioning wall  108 . The direction indicated by an arrow mark X, which is perpendicular to the direction in which the needle is moved when the adhesive  104  is applied to the partitioning wall, is the direction in which each protrusion  108   b  of each partitioning wall  108  protrudes. 
     First, the steps for coating the partitioning wall  108  with the adhesive  104  by moving the needle along the center line of the partitioning wall  108 , which is parallel to the lengthwise direction (Y) of the partitioning wall  108 , will be described (assuming that amount of positional deviation of needle is 0 μm). As the adhesive  104  is applied from the needle to each of the portions of the partitioning walls  108 , which corresponds in position to the protrusion  108   b , the body of the applied adhesive  104  is spread across the entirety of this portion of the partitioning wall  108  (including protrusion  108   b ) by its own surface tension, and then, becomes stable in shape on this portion of the partitioning wall  108  because of its own viscosity ( FIG. 4(   a )). Thereafter, the needle is moved onto the portion of the partition wall  108 , which corresponds to the recess  108   a , while being made to continuously exude the adhesive  104  to coat this portion of the partitioning wall  108  with the adhesive. The body of the adhesive applied to this portion of the partitioning wall, that is, the portion which corresponds to the recess  108   a , remains thereon because of its own viscosity ( FIG. 4(   b )). In addition, the body of the adhesive  104  applied to the partitioning wall  108  is prevented from flowing into the recording liquid passages  106 , by the force generated by the meniscus which it forms along the edges between the recess and protrusion  108   b ; it remains stable in shape on the partitioning wall  108 . 
     Next, a case in which the adhesive  104  is applied to the top surface of the partitioning wall  108 , with the needle positioned 100 μm away from the center line (parallel to direction Y) of the partitioning wall  108  in the direction indicated by the arrow mark X, will be described. Also in this case, as the adhesive  104  is exuded from the needle while the needles is moved in the direction Y, the body of the applied adhesive  104  settles on the top surface of the partitioning wall  108 , except that it settles slightly away from the abovementioned center line. Thus, as the body of the applied adhesive  104  settles on the top surface of the partitioning wall  108 , it spreads beyond the edge of the recess  108   a . However, as it spreads beyond the edge of the recess  108   a , the portion of the body of the adhesive  104 , which has spread beyond the edge of the recess  108   a , is supported by the adjacent two protrusions  108   b . Further, also in this case, as soon as the adhesive  104  is applied to the top surface of the partitioning wall  108 , the body of the applied adhesive  104  is made to spread across the top surface of the partitioning wall  108  by its own surface tension, and yet, the body of the adhesive  104  on the top surface of the partitioning wall  108  is prevented from flowing into the recess  108   a , by its own viscosity, and the meniscus which it forms along the edges between the recess and protrusion  108   b . That is, also in this case, the adhesive  104  does not flow into the recess  108   a ; it remains stable on the top surface of the partitioning wall  108 . 
     To summarize, in this embodiment, both of the vertical surfaces (surface perpendicular to recording chip supporting surface) of each partitioning wall are provided with multiple protrusions  108   b , which are arranged in the lengthwise direction of the partitioning wall  108  with equal intervals, are multiple recesses  108   a  which also are arranged in the lengthwise direction of the partitioning wall  108  with equal intervals, so that the multiple protrusions  108   b  and multiple recesses  108   b  are alternately positioned in terms of the lengthwise direction of the partitioning wall  108 . Therefore, even the bodies of the applied adhesive  104  on the portions of each of the partitioning walls  108  remain stable in shape. Further, even in the case where the adhesive  107  is exuded onto the partitioning wall  108  with the needle slightly displaced relative to the partitioning wall  108 , the body of the adhesive  104  applied to the partitioning wall  108  satisfactorily remains on the partitioning wall  108 . 
     Further, in this embodiment, both of the vertical surfaces (surface perpendicular to recording chip supporting surface) of each partitioning wall are provided with multiple protrusions  108   b  and multiple recesses  108   a , which are arranged in the lengthwise direction of the partitioning wall  108  with equal intervals. However, as long as one of the two vertical surfaces of each partitioning wall  108  is provided with the above described protrusions  108   b  and recesses  108   a , the partitioning wall  108  can satisfactorily retain the body of the applied adhesive  104 . 
     Further, in this embodiment, all portions of the partitioning wall  108 , which have protrusions  108   b , are equal in the thickness w 2 . However, it is not mandatory that both of the vertical surfaces of each partitioning wall  108  are provided with multiple protrusions  108   b  and valleys  108   a . That is, as long as one of the two vertical surfaces of the partitioning wall  108  is provided with the protrusions  108   b  and recesses  108   a , the above described effect of satisfactorily holding the body of the applied adhesive  104  can be obtained. 
     In this embodiment, all the protrusions  108   b  are the same in the measurement w 2  (thickness). However, it is not mandatory that the all the protrusions  108   b  are the same in the measurement w 2 . As a matter of fact, it is preferable that the protrusions  108   b  closer to the lengthwise ends of the partitioning wall  108  are greater in thickness w 2  than those closer to the lengthwise center of the partitioning wall  108 , for the following reason. That is, it is at the beginning of the process of applying the adhesive  104  to the top surface of the partitioning wall  108  with the use of the dispenser that it is highly possible for the body of the applied adhesive  104  to flow down into the main recording liquid passages. Therefore, structuring the partitioning wall so that the protrusions  108   b  closer to the lengthwise ends of the partitioning wall  108  are greater in thickness w 2  than those closer to the center of the partitioning wall  108  is even more effective as the means for solving the problem that the adhesive  104  flows down into the main recording liquid passages after its application onto the top surface of the partitioning wall  108 . Once the body of the applied adhesive  104  settles on the top surface of the protrusions  108   b , it is prevented from flowing down into the main recording liquid passages, by the above described properties of the adhesive  104 . Therefore, the protrusions  108   b  closer to the center of the partitioning wall  108  may be relatively small in terms of the thickness w 2 . That is, structuring the partitioning wall  108  so that some of the protrusions  108   a  are smaller than the rest is preferable in that it makes the main recording liquid (ink) passage greater in recording liquid capacity while ensuring that the recording chip remains satisfactorily adhered to the recording chip supporting member. 
     Comparative Example 
     In the comparative example to the above described first preferred embodiment, the adhesive  104  was applied to the top surface of the partitioning wall which is 0.4 mm in thickness. That is, the partitioning wall in the comparative example is different from those in the above described first preferred embodiment in that the vertical surfaces of each partitioning wall  108  are not provided with multiple protrusions and multiple recesses. In terms of the adhesive viscosity, amount by which the adhesive is exuded, needle diameter, and needle speed, this comparative example is the same as the above described first preferred embodiment. 
     In the case of the comparative example, as the adhesive was applied to the top surface of the partitioning wall, with the needle displaced by 50 μm in the direction perpendicular to the lengthwise direction of the partitioning wall, from the center line of the partitioning wall in terms of the widthwise direction of the partitioning wall, the adhesive flowed down from the top of the partitioning wall into the main recording liquid passages, and therefore, some of the main recording liquid passages were partially or fully plugged by the adhesive. 
     Embodiment 2 
       FIG. 6(   a ) is a plan view of the recording chip facing surface of the supporting member, and  FIG. 6(   b ) is an enlarged plan view of a part of one the partitioning walls of the supporting member  150 . 
     Also in this embodiment, the recording chip is bonded to the supporting member  150 , which has the partitioning walls  108 , which has the protrusions  108   b  and recesses  108   a , which are alternately positioned in terms of the lengthwise direction of the partitioning walls. However, in this embodiment, the protrusion  108   b  and recesses  108   a  are shaped so that their contours, at a plane which is parallel to the primary surfaces of the supporting member  150 , are made up of straight lines and curved lines. More specifically, the contour of the cross section of each recess  108   a  has a curvature that protrudes toward the centerline of the partitioning wall  108 , which is parallel to the lengthwise direction of the partitioning wall  108 . Further, also in this embodiment, the portion of the partitioning wall  108 , which corresponds in position to the recess  108   a  is 0.4 mm in thickness, whereas the portion of the partitioning wall  108 , which corresponds in position to the protrusion  108   b , is 0.7 mm in thickness. Further, the measurements of the recess  108   a  and protrusion  108   b  in terms of the lengthwise direction of the partitioning wall  108  are both 0.4 mm, and the pitch of the protrusions  108   b  is 0.8 mm. Further, the depth of the recess  108   a  in terms of the direction perpendicular to the surface of  FIG. 6  is 0.4 mm. 
     Also in this embodiment, an adhesive which was 14,000 mPa×s in viscosity, and 1.8 in thixo-ratio was used as the adhesive  104 . Further, the diameter of the needle of the adhesive dispenser was 0.4 mm in diameter as it is in the first embodiment. Further, the adhesive  104  was directly applied to the partitioning walls  108  and the other recording chip adhesion areas of the supporting member  150 , from the needle (unshown) of the dispenser. 
     As the adhesive  104  was applied to the partitioning wall  108  while moving the needle following the center line of the partitioning wall, which is parallel to the lengthwise direction Y of the partitioning wall (assuming that positional deviation of needle relative to partitioning wall  108  is 0 μm), the partitioning wall  108  was satisfactorily coated with the adhesive  104 . Further, even as the adhesive  104  was applied to the partitioning wall  108 , with the needle displaced by 100 μm in the direction X from the center line of the partitioning wall  101 , which is parallel to the lengthwise direction of the partitioning wall  108 , the partitioning wall  108  was satisfactorily coated with the adhesive  104 . Further, the supporting member was designed so that the contour of the surface of the partitioning wall  108  is made up of a combination of straight lines (which correspond to protrusions  108   b ) and curved lines (which correspond to recesses  108   a ). Thus, this embodiment is preferable to the first embodiment in that bubbles are less likely to become stagnant in the recesses of the main recording liquid passages of a recording head having the supporting member  150  in this embodiment than in a recording head having the supporting member  150  in the first embodiment. Further, the supporting member  150  can be formed by injection molding or the like. Therefore, a supporting member, the recesses of which are curved in cross section, is superior in terms of the separation from a mold, and therefore, it can be more satisfactorily formed than a supporting member, the recesses of which have straight lines in cross section. Therefore, this embodiment is preferable. 
     [Evaluation of Ink jet Recording Head Performance Recovery Based on Suction] 
     The ink jet recording heads in the first and second preferred embodiments were evaluated in their performance recovery based on bubble suction. Ordinarily, before an ink jet recording head begins to be used for an actual recording operation, an operation for restoring the ink jet recording head in performance is carried out. More specifically, recording liquid is suctioned through the recording liquid ejecting orifices by a mechanism with which the main assembly of the recording apparatus is provided to remove the bubbles in the main recording liquid passages  106  or the like in order to restore the recording head in performance That is, in order to prevent the mounting of an ink jet recording head into the main assembly of an ink jet recording head, from affecting the recording head in terms of image quality, the recording apparatus is designed so that as a recording head is mounted in the main assembly of the recording apparatus, the recording head is subjected to the above described operation for suctioning the recording head to remove the bubbles in the recording head to restore the recording head in performance. 
     Thus, the ink jet recording heads in the first and second preferred embodiments were evaluated in their performance regarding the performance restoration based on suction. More specifically, the ink jet recording heads were mounted in the main assembly of an ink jet recording apparatus, and were suctioned by the main assembly&#39;s performance recovery mechanism. Then, the ink jet recording heads were evaluated in recording performance. The recording head in the second embodiment recorded more satisfactory images than the recording head in the first embodiment. That is, the images formed by the recording head in the second embodiment showed virtually no sign of being affected by the presence of bubbles, even when the recording head in the second embodiment was made roughly 20% smaller in the amount by which recording liquid was suctioned than the recording head in the first embodiment. In addition, the recording head in the second embodiment was shorter than the recoding head in the first embodiment, in the length of time necessary for the performance recovery operation based on suction (length of time suctioning mechanism needs to be driven). That is, the recording head in the second embodiment was satisfactorily restored in recording performance even when it was made smaller than the recording head in the first embodiment, in the amount of load to which the suction-based recording performance restoration mechanism of the main assembly of the recording apparatus was subjected. 
     This result is attributable to the fact that the recording chip supporting member  150  of the recording head in the second embodiment is designed so that the contour of each of its recesses  108   a  is curved ( FIG. 6 ). Therefore, it is easier for recording liquid to flow through the portion of the main recording liquid passages of the recording head in the second embodiment, which corresponds to the recess  108   a , which is between the adjacent two protrusions  108   b  than that in the first embodiment. That is, bubbles are less likely to become stagnant in the recess  108   a  of the recording head in the second embodiment than that in the first embodiment. Therefore, the recording head in the second embodiment can be satisfactorily rid of bubbles even if it is smaller than the recording head in the first embodiment, in the amount by which recording liquid is suctioned. 
     [Miscellanies] 
     In the above given description of the first and second preferred embodiments of the present invention, only a couple of shapes were mentioned for the recess  108   a  and protrusion  108   b . However, the two embodiments are not intended to limit the present invention in terms of the shape for the recess  108   a  and protrusion  108   b . That is, the shapes for the recess  108   a  and protrusion  108   b  may be selected as fit, as long as the selected shapes are suitable for reliably retaining the adhesive  104  on the partitioning wall  108 . In other words, the width of the recess  108   a , width of the protrusion  108   a , measurement of recess  108   a  in terms of the direction parallel to the lengthwise direction of the partitioning wall, measurement of the protrusion  108   b  in terms of the direction parallel to the lengthwise direction of the partitioning wall  108 , pitch of the protrusions, may be set as fit. Further, the shape and depth for the recess  108   a  may be set as necessary, in consideration of the level of easiness at which the recording liquid is desired to flow through the main recording liquid passages, which corresponds in position to the recess  108   a.    
     Further, each of the preferred embodiments and comparative example was described with reference to the ink jet recording heads structured so that the recording chip  101  and recording liquid container  109  are physically integral with each other. However, the present invention is applicable to an ink jet recording head, the recording chip  101  and recording liquid container  109  of which are physically independent from each other. Further, the two preferred embodiments and the comparative example were described with reference to the recording heads, the supporting member  150  of which for supporting the recording chip  101  was formed of a resinous substance. However, the supporting member  150  may be formed of a ceramic or the like. 
     While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. 
     This application claims priority from Japanese Patent Application No. 076102/2008 filed Mar. 24, 2008, which is hereby incorporated by reference herein.