Patent Publication Number: US-7712870-B2

Title: Ink jet recording head with sealant filling region in substrate

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink jet recording head used for a recording apparatus in which recording liquid (e.g., ink) is discharged from a discharge opening to form ink droplets for a recording operation. 
     2. Description of the Related Art 
     A general ink jet recording cartridge will be described with reference to  FIG. 10 . The following section will exemplarily describe a color cartridge from which yellow, magenta, and cyan inks are discharged for a printing operation. 
     In  FIG. 10 , an ink jet recording cartridge  601  is structured by integrating an ink jet recording head section including a recording element substrate  702  made of silicon for example and an ink container section  709  including therein ink. The recording element substrate  702  is a heater for allowing ink to be discharged by conversion of electrical energy to thermal energy. The recording element substrate  702  is composed by a nozzle plate that includes: a substrate including a wiring for transmitting electrical energy supplied from an ink jet recording apparatus to the heater; a flow path for supplying ink to the heater; and a plurality of ink discharge openings for discharging ink. One recording element substrate  702  includes discharge opening rows  703 ,  704 , and  705  for discharging ink of three colors of yellow, magenta, and cyan. The electric wiring substrate  706  functions to transmit an electric signal from the ink jet recording apparatus to the recording element substrate  702  by transmitting an electric signal from the ink jet recording apparatus to the recording element substrate  702  via an external signal input terminal  707 . The electric wiring substrate  706  is electrically connected to the recording element substrate  702  at two end faces of the recording element substrate  702  so that the electric connection section is covered by sealant  708  for protection from ink. 
     Next, the general structure of the periphery of the recording element substrate  702  in the ink jet recording head section will be described with reference to  FIG. 11  and  FIG. 12 . 
       FIG. 11  is a plan view illustrating a support substrate  802  and a support plate  804 . The support substrate  802  is made of material such as alumina in order to accurately adhere and fix the recording element substrate  702  and is subjected to a polishing processing. The support plate  804  fixes and supports the electric wiring substrate  706  and is made of the same material as that of the support substrate  802 . 
       FIG. 12  is a cross-sectional view taken along a line XII-XII of  FIG. 10 . The support substrate  802  includes an ink supply opening  803  for supplying ink in an ink container to the recording element substrate  702 . The recording element substrate  702  is attached so that the ink supply opening  803  communicates with the ink supply opening of the recording element substrate  702 . A support plate  804  is also attached in order to support the recording element substrate  702 . A space between the recording element substrate  702  and the support plate  804  is sealed by sealant  805  (e.g., resin) in order to prevent ink from entering the space. The purpose of this sealing is to prevent, when ink enters the space between the recording element substrate  702  and the support plate  804  and is attached to an end of a side face of the recording element substrate  702 , silicon exposed at the end of the side face of the recording element substrate  702  from being eluted and to protect the electric connection section from ink. This sealant  805  is generally thermosetting resin that can be used in a manufacture step in a relatively easy manner. 
     An accuracy at which the recording element substrate  702  is attached has a direct influence on a recording accuracy of the ink jet recording apparatus. To improve the attachment accuracy or to realize a manufacture step having a high yield, various suggestions have been conventionally made. Japanese Patent Laid-Open No. H10-44420 has proposed that a recording element substrate is fixed by adhering a support substrate having substantially the same thermal characteristic as that of the recording element substrate is adhered to the recording element substrate. Japanese Patent Laid-Open No. 2002-19119 has proposed a method for preventing a recording element substrate from being broken due to different line coefficients of expansion, by adhering a support substrate made of alumina for example between the recording element substrate and the support member. 
     Cost for a recording element substrate is the highest cost among manufacturing costs for an ink jet recording head. In order to reduce the cost for the recording element substrate, a demand has been recently raised to minimize the size of the recording element substrate so that more recording element substrates can be obtained from one wafer. However, when the substrate size is reduced while leaving the discharge opening arrangement unchanged, a wall section around the discharge opening is reduced, resulting in a wall section having a poor rigidity in the recording element substrate. Since the periphery of the recording element substrate is sealed by the thermosetting resin as described above, the thermosetting resin generates therein, when the thermosetting resin cures and shrinks, a stress that is applied to the recording element substrate. The following section will describe the outline of the stress that is caused when the sealant cures and shrinks and that is applied to the recording element substrate. 
       FIG. 13  illustrates the stress in the sealant  805  applied to the recording element substrate  702 . When a recording head is manufactured, the recording element substrate  702 , the support plate  804 , and the support substrate  802  and adhesive agent and sealant for fixing them are placed in an oven heated at 100 degrees. Then, the respective members expand by heat and cure while expanding. The respective members have different expansion rates depending on the materials thereof. When the respective cured members are taken out from the oven, the temperatures of the respective members decline to a room temperature and thus the shapes of the expanded members return to the original shapes. It is known that general thermosetting sealant cures and shrinks by about 5%. Thus, stresses shown by arrows in  FIG. 13  are caused in the sealant  805  due to the curing and shrinkage of the respective members and the changes with a temperature of the respective members. The opposite side face of the recording element substrate  702  is also in the same condition, although  FIG. 13  illustrates only a part of the ink jet recording head and thus does not show the condition of the opposite side face. Specifically, a force from the side face to outside is applied to the recording element substrate  702 . When the stress as described above is applied to the recording element substrate  702  as described above, a sectional area at which the recording element substrate  702  has a contact with the sealant  805  is small as shown in  FIG. 12  and thus tends to deform when being applied with the stress. Furthermore, the recording element substrate  702  has different opening spaces at a face having a contact with the support substrate  802  and a face opposed to the face. Thus, when the sealant  805  applies a force to the recording element substrate  702 , the recording element substrate  702  may deform while having warpage. When a recording head using such a deformed recording element substrate  702  is used for a recording operation, ink droplets discharged from the recording head of an ink jet recording apparatus adhere to a paper in a dislocated manner, thus causing a deteriorated recording quality. Furthermore, the recording element substrate  702  may be broken in a manufacture process. 
     When the electric wiring substrate  706  and the support plate  804  for supporting the electric wiring substrate  706  from the lower side that respectively have opening sections are adhered by adhesive agent so that the opening sections of the former and the latter are superposed on the other hand, excessive adhesive agent may protrude from an end of the joint face of the joined opening sections. When this protruded adhesive agent moves from the end face of the electric wiring substrate to reach the upper surface, an inconvenience such as a favorable electric joint of the electric joint section or a contact of the electric joint section with a recording medium may be caused. In order to prevent this, the electric wiring substrate  706  has an opening smaller than an opening of the support plate  804 . This causes adhesive agent protruding from the end face of the joint section to go down to the interior of the opening section of the support plate  804 , thus preventing the adhesive agent from reaching the upper surface of the electric wiring substrate  706 . 
     Another requirement has been made according to which a needle for coating adhesive agent desirably does not have a small inner diameter from the viewpoint of a manufacture efficiency. The present invention has been made in view of the above problems. It is an objective of the present invention to provide an ink jet recording head by which a recording operation having a high recording quality can be stably performed without causing deformation or breakage of the recording element substrate  702  and the manufacture cost is low. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, an ink jet recording head comprises a recording element substrate including a discharge opening row for discharging ink; and a support substrate that has a support section for supporting the recording element substrate and that has a sealant filling region adjacent to the support section, wherein the filling region is divided, by a divider, to a filling region adjacent to the recording element substrate and a filling region away from the recording element substrate. 
     In the ink jet recording head of the present invention, a sealant filling groove for protecting a substrate from ink includes a salient. The existence of this salient can reduce the volume of filler to reduce the stress caused by the curing and shrinkage of the filler to reduce the influence by the stress on the recording element substrate, thereby realizing an ink jet recording head that can provide a recording operation with a high recording quality. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view of an ink jet recording cartridge of the first embodiment in which the respective parts are disassembled; 
         FIG. 2A  is a plan view illustrating a top face of a recording element substrate; 
         FIG. 2B  is a plan view illustrating a back face of the recording element substrate; 
         FIG. 3  is a plan view illustrating a support member having a salient of the first embodiment; 
         FIG. 4  is a cross-sectional view schematically illustrating a part of a joint section of the salient formed in the support member and the recording element substrate; 
         FIG. 5  illustrates stress caused when sealant in the support member including the salient cures and shrinks; 
         FIG. 6  illustrates sealant filled between the recording element substrate and the electric wiring substrate by a needle; 
         FIG. 7  is a plan view illustrating a support member and a salient of the second embodiment; 
         FIG. 8  is a plan view illustrating a support member and a salient of the third embodiment; 
         FIG. 9A  is a longitudinal cross-sectional view illustrating sealant filled into a support member; 
         FIG. 9B  is a top view illustrating sealant filled into the support member; 
         FIG. 10  is a perspective view illustrating a conventional ink jet recording cartridge; 
         FIG. 11  is a plan view illustrating conventional support substrate and support plate; 
         FIG. 12  is a cross-sectional view taken along a line C-C of  FIG. 10 ; and 
         FIG. 13  illustrates how stress in the sealant is applied to the recording element substrate. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     First Embodiment 
     Hereinafter, an embodiment of the present invention will be described in detail. 
       FIG. 1  is a schematic perspective view illustrating an ink jet recording cartridge of this embodiment in which the respective parts are disassembled.  FIG. 2A  is a plan view showing a top face of a recording element substrate H 1101 .  FIG. 2B  illustrates a back face of the recording element substrate H 1101 . The recording element substrate H 1101  includes, at one side of an Si substrate having a thickness of 0.62 mm, a plurality of energy generation elements for discharging ink (not shown) (hereinafter also may be referred to as heater) and an electric wiring (not shown) (e.g., Al) for supplying power to the respective energy generation elements that are formed by a film formation technique. The recording element substrate H 1101  also includes a plurality of ink flow paths (not shown) provided to correspond to the respective heaters and a plurality of ink discharge openings H 1103  that are formed by a photolithography technique. An ink supply opening H 1102  for supplying ink to a plurality of ink flow paths is provided in a face opposite to the face including an ink discharge opening. 
     An electric wiring substrate H 1301  includes: a device hole DH for attaching the recording element substrate H 1101 ; an electrode terminal H 1302  corresponding to an electrode H 1104  of the recording element substrate H 1101 ; and an external signal input terminal H 1303  for receiving a control signal from a recording apparatus body. This external signal input terminal H 1303  and the electrode terminal H 1302  are connected by a copper foil wiring. 
       FIG. 3  is a plan view illustrating a support member H 1501  having a salient H 1503  of this embodiment. The support member H 1501  is formed by a resin molding and uses in this embodiment resin material mixed with glass filler of 35% for improving the rigidity. This support member H 1501  has an ink supply path H 1502  from an ink storage section H 1506  (see  FIG. 5 ) and has, at a joint face H 1504  with the recording element substrate, salients H 1503  at both sides of the ink supply path H 1502  that are provided so as to be in parallel with the ink supply path H 1502 . 
       FIG. 4  is a cross-sectional view schematically illustrating a part of a joint section of the salients H 1503  formed in the support member H 1501  and the recording element substrate H 1101 . The recording element substrate H 1101  is adhered to the support member H 1501  by thermosetting adhesive agent H 1201  and the recording element substrate H 1101  is surrounded by the sealant H 1202 . The adhesive agent H 1201  and the sealant H 1202  desirably have a low curing temperature, cure in a short time, and have ink resistance. In this embodiment, the adhesive agent H 1201  and the sealant H 1202  are thermosetting resin mainly including epoxy resin. When this adhesive agent is used, an adhesion layer is provided to have a thickness of about 50 μm. The adhesive agent H 1201  and the sealant H 1202  used in this embodiment provide, when cured for one hour at  100  degrees, desired performances such as the above-described ink resistance and adhesiveness. The above adhesive agent and sealant H 1202  are not limited to the above ones and may be other ones so long as they satisfy conditions required by the respective ink jet recording heads. 
       FIG. 5  illustrates stress caused when the sealant H 1202  cures and shrinks in the support member H 1501  including the salient H 1503  of this embodiment. The existence of the salient H 1503  as described above can reduce the volume to which the sealant H 1202  is filled and thus the volume of filled sealant H 1202  can be reduced. Consequently, the volume of the filled sealant H 1202  adjacent to the recording element substrate H 1101  is also reduced and the amount of the curing and shrinkage is also reduced. Thus, the stress applied to the recording element substrate H 1101  can be reduced. Thus, an influence by the dislocation of the recording element substrate H 1101  for example can be reduced to a level causing no problem. 
     In this embodiment, the salient H 1503  is provided so as to face an end face in the longitudinal direction of the recording element substrate H 1101 . The reason is that, as can be seen from  FIGS. 2A and 2B , the end face in the longitudinal direction of the recording element substrate H 1101  is close to the ink supply opening and thus an external force to the end face in the longitudinal direction tends to cause the recording element substrate H 1101  to deform or be broken. The salient also can be provided at a position in parallel with an end section that is not in the longitudinal direction. In this case, the stress applied to the recording element substrate H 1101  also can be reduced to prevent the dislocation by the stress. 
     The interval between this salient H 1503  and the recording element substrate H 1101  is preferably minimized. The minimized interval can further reduce the stress applied to the recording element substrate H 1101 . 
     Next, the following section will describe how to prevent the adhesive agent H 1304  from being protruded from a space between the support member H 1501  and the electric wiring substrate H 1301  when the adhesive agent H 1304  is provided therebetween to fix the former and the latter. 
       FIG. 6  illustrates sealant H 1202  filled in the space between the recording element substrate H 1101  and the electric wiring substrate H 1301  by a needle H 1203 . The salient H 1503  provided in a sealing coating region prevents the stress of the sealant from increasing. The electric wiring substrate H 1301  has an opening section that is smaller than the opening section of the joint face of the electric wiring substrate H 1301  of the support member H 1501  to provide a space under the electric wiring substrate H 1301  to store the adhesive agent H 1304 . This can prevent the adhesive agent H 1304  from protruding to the upper face and side face of the electric wiring substrate H 1301 , thus preventing the adhesive agent H 1304  to be attached to an adhesion tool used in the manufacture process. 
     Second Embodiment 
     The second embodiment in the present invention will be described with reference to the drawing. 
       FIG. 7  is a plan view illustrating the support member H 1501  and the salient H 1503  of this embodiment. 
     The second embodiment has the same structure as that of the first embodiment except for the length of the salient H 1503 . The salient H 1503  of the second embodiment is obtained by shortening both end sections in the longitudinal direction of the salient of the first embodiment to communicate a sealing groove H 1505 B adjacent to the recording element substrate H 1101  with a sealing groove H 1505 A not adjacent to the recording element substrate H 1101 . The structure as described above allows filled sealant to pass both side ends of the salient H 1503  to flow into both of the filling grooves H 1505 A and  1505 B, thus providing an identical fluid level to sealant in both of the filling grooves. Then, the sealant H 1202  is filled until the fluid level of sealant is at the same height as that of a face of the recording element substrate H 101  having the discharge opening. 
     When the recording apparatus performs a recording operation, ink or dust for example attached to a discharge opening face is wiped so that the nozzle can always discharge ink in a correct manner. When a face formed by the sealant H 1202  is different from a face having the discharge opening of the recording element substrate H 1101  to prevent ink from being wiped, ink may be left on the sealant H 1202  and has an increased viscosity. When the ink having an increased viscosity is transferred by the subsequent wiping operation to the discharge opening, the ink may clog the discharge opening. In order to avoid the defect as described above, the sealant H 1202  is filled to the same height as that of the face of the recording element substrate H 1101  having the discharge opening. 
     Although this embodiment shortened both side ends of the salient H 1503 , the above objective also can be achieved by shortening one side end or by eliminating the center part of the salient so as to divide the salient H 1503  at the center. However, both filling grooves preferably communicate with each other at end sections in consideration of an influence by the stress on the recording element substrate H 1101 . Alternatively, instead of completely removing a part of the salient, the salient also may include a notch through which the sealant H 1202  can flow. 
     Third Embodiment 
     The third embodiment in the present invention will be described with reference to the drawings.  FIG. 8  is a plan view illustrating the support member H 1501  and the salient H 1503  of the third embodiment.  FIG. 9A  is a longitudinal cross-sectional view illustrating sealant filled to the support member.  FIG. 9B  is a top view illustrating sealant filled to the support member. The third embodiment provides, as in the above-described embodiments, the salient H 1503  to reduce the influence by the stress to the recording element substrate H 1101 . The third embodiment has the same structure as that of the second embodiment except that the filling groove H 1505 B in which the sealant H 1202  is filled has a shallower depth. The existence of the filling groove H 1505 B having a shallower depth as in this embodiment can reduce the amount of filled sealant H 1202  to reduce the shrinkage after the curing. This can reduce the stress applied to the recording element substrate H 1101 . Furthermore, the volume of the filling groove H 1505 B is designed to be higher than that of the adhesive agent H 1304  when the adhesive agent H 1304  protrudes. Thus, the adhesive agent H 1304  is prevented from protruding to the upper face or side face of the electric wiring substrate. 
     The structure as described above can reduce an absolute amount of the sealant H 1202  to reduce the stress to the recording element substrate H 1101  when the sealant H 1202  cures and shrinks. Thus, an ink jet recording head can be realized that can provide a recording operation with a high recording quality. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2006-136702, filed May 16, 2006, which is hereby incorporated by reference herein in its entirety.