Ink jet printer head and method of producing ink jet printer head

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an ink jet printer head including an ejector unit having a plurality of nozzles each of which ejects a droplet of ink toward a recording medium, and a cover member (e.g., a cover plate) which is fixed via a sealing portion (e.g., a sealing agent) to the ejector unit, and also relates to a method of producing an ink jet printer head.

[0003] 2. Discussion of Related Art

[0004] For example, Document <b>1</b> (i.e., Japanese Patent Application Publication No. 2002-067341 A1) or Document <b>2</b> (i.e., Japanese Patent Application Publication No. 2002-234144 A1) discloses an ink jet printer head including an ejector unit having a plurality of nozzles each of which ejects a droplet of ink toward a recording medium, and a cover plate which is fixed via a sealing agent to the ejector unit.

[0005] More specifically described, the ink jet printer head disclosed by each of the above-indicated two publication documents employs a plurality of ejector units each of which has, in an outer surface thereof, a plurality of nozzles arranged in at least one array; a cover plate which has a plurality of openings and covers the ejector units such that the array of nozzles of each of the ejector units is exposed through a corresponding one of the openings; and a frame member supporting the ejector units and the cover plate. The ink jet printer head is assembled in a state in which the array of nozzles of each one of the ejector units is accurately positioned relative to the array of nozzles of the other ejector unit or units. In this state, a sealing agent is provided, between the cover plate and each of the ejector units, along the periphery of a corresponding one of the openings of the cover plate, so that the cover plate covers the respective outer surfaces of the ejector units. Respective opposite surfaces of the ejector units that are opposite to the respective outer surfaces thereof are covered by a bottom wall of the frame member. When an adhesive is charged into through-holes that are formed through the thickness of the bottom wall of the frame member, the ejector units are fixed, with the adhesive, to the bottom wall in the above-indicated state. Simultaneously, the cover plate is fixed, with the adhesive, to the bottom wall of the frame member.

[0006] Although, in the above-described ink jet printer head, the ejector units are fixed to the bottom wall of the frame member, with the adhesive charged via the through-holes formed in the bottom wall, the dimensions and positions of the through-holes are more or less limited in view of the structure and strength of the bottom wall, and accordingly the positions where the adhesive is applied are limited. Thus, the adhesive strength of the ejector units cannot be sufficiently increased.

[0007] In addition, in a state before the ejector units and the cover plate are finally fixed with the adhesive to the frame member, the ejector units and the cover plate are just temporarily adhered to each other with the sealing agent only. Therefore, the cover plate and each of the ejector units may be displaced relative to each other and accordingly the sealing agent may flow or move. Consequently defects of adhesion, such as bubbles or uneven adhering, and/or defects of sealing, such as gaps or uneven sealing may occur to those portions of the printer head that are sealed by the sealing agent.

SUMMARY OF THE INVENTION

[0008] It is therefore an object of the present invention to provide an ink jet printer head, and a method of producing an ink jet printer head, each of which is free from at least one of the above-indicated problems.

[0009] It is another object of the present invention to provide an ink jet printer head, and a method of producing an ink jet printer head, each of which can enjoy a high adhesive strength of one or more ejector units.

[0010] It is another object of the present invention to provide an ink jet printer head, and a method of producing an ink jet printer head, each of which can prevent defects that may occur to adhesion or sealing between one or more ejector unit or units and a cover member.

[0011] According to a first aspect of the present invention, there is provided an ink jet printer head, comprising at least one ejector unit having, in one of opposite surfaces thereof, a plurality of nozzles each of which ejects a droplet of ink toward a recording medium; a cover member which has at least one first opening and is fixed to the one surface of the at least one ejector unit such that the nozzles of the at least one ejector unit are exposed through the at least one first opening; a frame member including a bottom wall to which the other surface of the at least one ejector unit is fixed; at least one sealing portion which seals the at least one ejector unit and the cover member to each other along a periphery of the at least one first opening of the cover member; at least one first adhering portion which adheres, and thereby fixes, the cover member to the one surface of the at least one ejector unit, so as to provide a subassembly including the at least one ejector unit and the cover member; and at least one second adhering portion which adheres, and thereby fixes, the subassembly including the at least one ejector unit and the cover member, to the bottom wall of the frame member, such that the other surface of the at least one ejector unit is fixed to the bottom wall of the frame member.

[0012] According to the first aspect of the present invention, the first adhering portion adheres, and thereby fixes, the ejector unit and the cover member to each other. Therefore, the ejector unit and the cover member can be fixed to each other without any restraints resulting from the structure of the bottom wall of the frame member. In addition, the second adhering portion adheres, and thereby fixes, the subassembly including the ejector unit and the cover member, to the bottom wall of the frame member. Thus, the adhesive strength of the ink jet printer head can be improved.

[0013] In addition, even in a state before the subassembly including the ejector unit and the cover member is fixed to the bottom wall of the frame member, the ejector unit and the cover member are fixed to each other by the first adhering portion. Therefore, the ejector unit and the cover member can be fixed in position relative to each other, irrespective of to what degree the sealing portion has hardened. Thus, the ink jet printer head is freed of the problem that the ejector unit and the cover member are displaced relative to each other and the sealing portion flows or deforms and accordingly suffers sealing defects such as gaps or uneven sealing.

[0014] According to a second aspect of the present invention, there is provided a method of producing an ink jet printer head including at least one ejector unit having, in one of opposite surfaces thereof, a plurality of nozzles each of which ejects a droplet of ink toward a recording medium, a cover member having at least one first opening, and a frame member including a bottom wall, the method comprising the steps of providing, between the at least one ejector unit and the cover member, a sealing agent along a periphery of the at least one first opening of the cover member, such that the at least one ejector unit and the cover member are sealed to each other, and such that the nozzles of the at least one ejector unit are exposed through the at least one first opening of the cover member, adhering and fixing, with a first adhesive, the at least one ejector unit and the cover member to each other, so as to provide a subassembly including the at least one ejector unit and the cover member, and adhering and fixing, with a second adhesive, the subassembly including the at least one ejector unit and the cover member, to the bottom wall of the frame member.

[0015] According to the second aspect of the present invention, the ejector unit and the cover member are adhered and fixed to each other with the first adhesive. Therefore, the ejector unit and the cover member can be fixed to each other without any restraints resulting from the structure of the bottom wall of the frame member. In addition, the subassembly including the ejector unit and the cover member is adhered and fixed to the bottom wall of the frame member with the second adhesive. Thus, the adhesive strength of the ink jet printer head can be improved.

[0016] In addition, even in a state before the subassembly including the ejector unit and the cover member is fixed to the bottom wall of the frame member with the second adhesive, the ejector unit and the cover member are fixed to each other with the first adhesive. Therefore, the ejector unit and the cover member can be fixed in position relative to each other, irrespective of to what degree the sealing agent provided between those two elements has hardened. Thus, the ink jet printer head is freed of the problem that the ejector unit and the cover member are displaced relative to each other and the sealing agent flows or moves and accordingly suffers sealing defects such as gaps or uneven sealing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and optional objects, features, and advantages of the present invention will be better understood by reading the following detailed description of the preferred embodiments of the invention when considered in conjunction with the accompanying drawings, in which:

[0018]FIG. 1 is an exploded, perspective view of an ink jet printer head to which the present invention is applied;

[0019]FIG. 2 is an exploded, perspective view of the printer head of FIG. 1, the printer head taking an inverted position;

[0020]FIG. 3 is a perspective view of the printer head of FIG. 1, the printer head being in an assembled state;

[0021]FIG. 4 is a bottom view of a frame member of the printer head of FIG. 1;

[0022]FIG. 5 is a cross-section view of the printer head of FIG. 1, taken along <b>5</b>-<b>5</b> in FIG. 4, the printer head being in an exploded state;

[0023]FIG. 6 is a cross-section view of the printer head of FIG. 1, taken along <b>6</b>-<b>6</b> in FIG. 4, the printer head being in the assembled state;

[0024]FIG. 7 is a cross-section view of the printer head of FIG. 1, taken along <b>7</b>-<b>7</b> in FIG. 4;

[0025]FIG. 8 is a plan view of a subassembly including two ejector units and a cover plate of the printer head of FIG. 1;

[0026]FIG. 9 is a perspective view of each ejector unit of the printer head of FIG. 1;

[0027]FIG. 10 is a perspective view of a cavity plate and a nozzle sheet of each ejector unit of the printer head of FIG. 1;

[0028]FIG. 11 is an enlarged, perspective view of the cavity plate of FIG. 10, showing a transverse cross section of the cavity plate;

[0029]FIG. 12 is a transverse cross section view of the ejector unit of FIG. 9;

[0030]FIG. 13 is an exploded, perspective view of a piezoelectric actuator of FIG. 12;

[0031]FIG. 14 is an exploded, perspective view of respective portions of the cavity plate and the piezoelectric actuator shown in FIG. 12;

[0032]FIG. 15 is a view for explaining a state in which the two ejector units and the cover plate are positioned relative to each other in a method of producing the ink jet printer head of FIG. 1, to which the present invention is also applied;

[0033]FIGS. 16A, 16B, and <b>16</b>C are views for explaining a sealing step of the method of producing the ink jet printer head of FIG. 1;

[0034]FIGS. 16D and 16E are views for explaining a first adhering step of the method of producing the ink jet printer head of FIG. 1;

[0035]FIGS. 17A and 17B are cross-section views, taken along <b>17</b>A-<b>17</b>A and <b>17</b>B-<b>17</b>B in FIG. 4, respectively, for explaining a second adhering step of the method of producing the ink jet printer head of FIG. 1;

[0036]FIG. 18A is a cross-section view of another ink jet printer head as a second embodiment of the present invention; and

[0037]FIG. 18B is a plan view of four ejector units and a cover plate of the ink jet printer head of FIG. 18A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, there will be described preferred embodiments of the present invention by reference to the drawings. As shown in FIG. 1, an ink jet printer head <b>1</b> as an embodiment of the present invention includes a frame member <b>2</b>, a plurality of (e.g., two) ejector units <b>6</b>, a cover plate <b>44</b> as a cover member, a plurality of sealing portions <b>60</b> (FIG. 6), a plurality of first adhering portions <b>61</b> (FIG. 6), and a plurality of second adhering portions <b>62</b> (FIG. 6). The frame member <b>2</b> is formed, by injection molding, of a synthetic resin such as polyethylene or polypropylene. The two ejector units <b>6</b> are provided on a lower surface of the frame member <b>2</b>, and each of the ejector units <b>6</b> has, in an outer or lower surface thereof, a plurality of nozzles <b>54</b> which are arranged in two arrays (FIG. 10) and each of which ejects a droplet of ink toward a surface of a recording medium such as a sheet of paper. The cover plate <b>44</b> is provided on the respective lower surfaces of the two ejector units <b>6</b>, and has two first openings <b>44</b><i>a </i>corresponding to the two ejector units <b>6</b>, respectively.

[0039] The frame member <b>2</b> includes a bottom wall <b>5</b> to which respective upper surfaces <b>6</b><i>a </i>of the two ejector units <b>6</b> that are opposite to the respective lower surfaces thereof are fixed, and has a generally box-like shape that opens upward. The frame member <b>2</b> includes a holder portion <b>3</b> to and from which four ink tanks, not shown, each as an ink supply source are attached and detached through the upper opening of the frame member <b>2</b>. The holder portion <b>3</b> has four ink supply passages <b>4</b><i>a</i>, <b>4</b><i>b</i>, <b>4</b><i>c</i>, <b>4</b><i>d </i>that are formed through the thickness of the bottom wall <b>5</b> and are connectable via respective packing members, not shown, to respective outlets of the four ink tanks.

[0040] The bottom wall <b>5</b> of the frame member <b>2</b> has second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>into which a second adhesive is injected to form the second adhering portions <b>62</b>, described later. A first adhesive or the first adhering portions <b>61</b> will be described later, too. The second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>are formed at respective locations where the second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>can be opposed to both the ejector units <b>6</b> and the cover plate <b>44</b>, as shown in FIG. 6. When the second adhesive is injected into the second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>opposed to the ejector units <b>6</b> and the cover plate <b>44</b>, a subassembly including the two ejector units <b>6</b> and the cover plate <b>44</b> is adhered, and fixed, to the lower surface (as seen in FIG. 1) of the bottom wall <b>5</b>. of the frame member <b>2</b>. In the present embodiment, the second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>are arranged in three arrays that extend parallel to the arrays of nozzles <b>54</b> of each of the two ejector units <b>6</b>, and the middle array of second openings <b>9</b>a are aligned with respective edge portions of the two ejector units <b>6</b> that are next to each other, as shown in FIG. 6. The two end arrays of second openings <b>9</b><i>b </i>(only one end array of second openings <b>9</b><i>b </i>are shown in FIG. 1) are aligned with respective opposite edge portions of the two ejector units <b>6</b> that are opposite to the above-indicated edge portions thereof, respectively, as also shown in the figure. Each array of second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>includes two openings that are distant from each other along an edge line or respective edge lines of one or two ejector units <b>6</b>. However, each array of second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>may be replaced with a single, elongate second opening. In either case, each array of second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>or each single elongate second opening does not extend over the entire length of the edge line or lines of one or two ejector units <b>6</b>.

[0041] As shown in FIG. 2, the bottom wall <b>5</b> of the frame member <b>2</b> includes two support portions <b>8</b> that support the two ejector units <b>6</b> such that the two ejector units <b>6</b> extend parallel to each other. One of the two support portions <b>8</b> is located between the middle array of second openings <b>9</b><i>a </i>and one of the two end arrays of second openings <b>9</b><i>b</i>; and the other support portion <b>8</b> is located between the middle array of second openings <b>9</b><i>a </i>and the other end array of second openings <b>9</b><i>b</i>. Two of the four ink supply passages <b>4</b><i>a</i>-<b>4</b><i>d </i>open in one of lengthwise opposite end portions of one of the two support portions <b>8</b>; and the other, two ink supply passages open in one of lengthwise opposite end portions of the other support portion <b>8</b>. A groove <b>46</b> having a generally <b>8</b>-shaped configuration in its plan view is formed around each of the respective open ends of the four ink supply passages <b>4</b><i>a</i>-<b>4</b><i>d</i>, and accommodates a ring-like packing member <b>47</b> that is formed of, e.g., a soft rubber and exhibits a sealing effect.

[0042] Each of the two ejector units <b>6</b> includes a nozzle sheet <b>43</b>, a cavity plate <b>10</b>, a piezoelectric actuator <b>20</b>, and a flexible flat cable <b>40</b>. The nozzle sheet <b>43</b> has the plurality of nozzles <b>54</b> which are arranged in the two arrays and each of which ejects the droplet of ink toward the recording sheet.

[0043] The cover plate <b>44</b> is formed of, e.g., a metallic sheet such as a stainless steel sheet, and is provided on the respective lower surfaces of the two ejector units <b>6</b> that have the nozzles <b>54</b> as shown in FIG. 2. The cover plate <b>44</b> protects the nozzles <b>54</b>, and their vicinities, of the respective nozzle sheets <b>43</b> of the two ejector units <b>6</b>, by preventing the direct contact of the recording sheet with the same <b>54</b>. In addition, the cover plate <b>44</b> prevents the ink from entering the respective electric systems (e.g., the respective piezoelectric actuators <b>20</b> and the respective flexible flat cables <b>40</b>) of the two ejector units <b>6</b>. Moreover, when a wiper blade, not shown, is used to remove the ink and/or dust that are deposited on the nozzles <b>54</b> and their vicinities, the wiper blade is contacted and slid on the cover plate <b>44</b>. The cover plate <b>44</b> includes a nozzle protection portion <b>44</b><i>d</i>, and two bent portions <b>44</b><i>b</i>, <b>44</b><i>c </i>that are bent from the nozzle protection portion <b>44</b><i>d</i>. The cover plate <b>44</b> has a constant thickness that is slightly greater than the thickness of the nozzle sheet <b>43</b> of each ejector unit <b>6</b>.

[0044] The cover plate <b>44</b> has the two first openings <b>44</b><i>a </i>that are formed through the thickness of the nozzle protection portion <b>44</b><i>d</i>, such that the two first openings <b>44</b><i>a </i>are aligned with the respective nozzle sheets <b>43</b> of the two ejector units <b>6</b>. The number of the first openings <b>44</b><i>a </i>of the cover plate <b>44</b> is equal to that of the ejector units <b>6</b> to be fixed to the frame member <b>2</b>. The two ejector units <b>6</b> and the cover plate <b>44</b> are adhered and fixed to each other, in a manner described below, such that through each of the first openings <b>44</b><i>a </i>of the cover plate <b>44</b>, the nozzles <b>54</b> of a corresponding one of the ejector units <b>6</b> are exposed to face the recording sheet.

[0045] As shown in FIG. 5, the cover plate <b>44</b> is positioned relative to the two ejector units <b>6</b>, such that the two first openings <b>44</b><i>a </i>of the cover plate <b>44</b> are. aligned with the respective nozzle sheets <b>43</b> of the two ejector units <b>6</b>. Then, a sealing agent <b>60</b> is provided, between the cover plate <b>44</b> and the two ejector units <b>6</b>, along the periphery of each of the two first openings <b>44</b><i>a</i>, so that the sealing agent <b>60</b> exhibits a sealing effect of preventing the ink from penetrating, by capillarity, into gaps that may remain between the ejector units <b>6</b> and respective portions of the cover plate <b>44</b> that define the first openings <b>44</b><i>a</i>. The sealing agent <b>60</b> is, for example, a silicone adhesive, or a gum adhesive. However, the silicone or gum adhesive may be replaced with a potting agent. In addition, the two ejector units <b>6</b> and the cover plate <b>44</b> are strongly adhered and fixed to each other by the first adhering portions <b>61</b> (<b>61</b><i>a</i>, <b>61</b><i>b</i>), as shown in FIG. 6.

[0046] The first adhering portions <b>61</b> are arranged in three arrays <b>61</b>a, <b>61</b>b that are parallel to the arrays P of nozzles <b>54</b>, as shown in FIG. 8. The middle array of first adhering portions <b>61</b><i>a </i>are aligned with the respective edge portions of the two ejector units <b>6</b> that are next to each other, as shown in FIG. 6; and the two end arrays of first adhering portions <b>61</b><i>b </i>are aligned with the respective opposite edge portions of the two ejector units <b>6</b> that are opposite to the above-indicated edge portions thereof, respectively. Thus, the first adhering portions <b>61</b> adhere and fix, to the cover plate <b>44</b>, the opposite edge portions of each of the two ejector units <b>6</b> that are parallel to the arrays P of nozzles <b>54</b>. As shown in FIGS. 6 and 8, the middle array of first adhering portions <b>61</b><i>a </i>are provided below, and along, the middle array of second openings <b>9</b><i>a</i>; and the two end arrays of first adhering portions <b>61</b><i>b </i>are provided below, and along, the two end arrays of second openings <b>9</b><i>b</i>, respectively. In each array of first adhering portions <b>61</b><i>a</i>, <b>61</b><i>b</i>, the first adhering portions are arranged at a regular interval of distance along an edge line or respective edge lines of one or two ejector units <b>6</b>. However, each array of first adhering portions <b>61</b><i>a</i>, <b>61</b><i>b </i>may be replaced with a single, continuous first adhering portion. A length, La, (FIG. 8) of each array of first adhering portions <b>61</b><i>a</i>, <b>61</b><i>b </i>in a direction parallel to the opposite edge portions of each ejector unit <b>6</b> is greater than a length, Lb, of each array of second openings <b>9</b><i>a</i>, <b>9</b><i>b</i>. The first adhering portions <b>61</b> adhere and fix the plurality of (e.g., two) ejector units <b>6</b> to the cover plate <b>44</b>, such that the arrays of nozzles <b>54</b> of each one of the two ejector units <b>6</b> are positioned relative to those of the other ejector unit or units <b>6</b>.

[0047] As shown in FIG. 6, the ink jet printer head <b>1</b> includes the second adhering portions <b>62</b> (<b>62</b><i>a</i>, <b>62</b><i>b</i>) that adhere and fix the subassembly including the two ejector units <b>6</b> and the cover plate <b>44</b>, to the bottom wall <b>5</b> of the frame member <b>2</b>. The second adhering portions <b>62</b><i>a</i>, <b>62</b><i>b </i>are formed of the second adhesive that is injected into the second openings <b>9</b><i>a</i>, <b>9</b><i>b</i>. Thus, as seen in the plan view of FIG. 8, the second adhering portions <b>62</b><i>a</i>, <b>62</b><i>b </i>are aligned with the second openings <b>9</b><i>a</i>, <b>9</b><i>b</i>, respectively, in a direction perpendicular to the bottom wall <b>5</b> of the frame member <b>2</b>. In addition, as shown in FIG. 6, the middle array of second adhering portions <b>62</b><i>a </i>is superposed on the middle array of first adhering portions <b>61</b><i>a </i>and thereby integrated with the same <b>61</b><i>a</i>; and the two end arrays of second adhering portions <b>62</b><i>b </i>are superposed on the two end arrays of first adhering portions <b>61</b><i>b </i>and thereby integrated with the same <b>61</b><i>b</i>, respectively.

[0048] The first and second adhering portions <b>61</b>, <b>62</b> may each be formed of an ultraviolet (UV) light sensitive adhesive that is hardened in a short time upon exposure to UV light. In this case, the first and second adhering portions <b>61</b>, <b>62</b> are hardened more quickly than the sealing agent <b>60</b>, and exhibit a sufficiently high adhesive strength after being hardened. Unlike the UV-light sensitive adhesive, the sealing agent <b>60</b> such as the silicone adhesive is not solidified, though the sealing agent <b>60</b> exhibits the sealing effect as described above. Small clearances that may remain between the outer periphery of the cover plate <b>44</b> and the frame member <b>2</b> are sealed with a sealing agent <b>45</b> such as a silicone adhesive, as shown in FIG. 7, like in the ink jet printer head disclosed by the previously-identified Document <b>1</b>.

[0049] In the ink jet printer head <b>1</b> constructed as described above and shown in, e.g., FIG. 8, the first adhering portions <b>61</b> are arranged in the three arrays substantially parallel to the arrays P of nozzles <b>54</b>, such that in each of the three arrays, the three or more (e.g., five) first adhering portions <b>61</b> are arranged at a regular interval of distance on a corresponding one of three straight lines; and the second adhering portions <b>62</b> are arranged in the three arrays substantially parallel to the arrays P of nozzles <b>54</b>, such that in each of the three arrays, the two second adhering portions <b>62</b> are distant from each other by a same distance, on a corresponding one of the three straight lines, and overlap the first adhering portions <b>61</b> of a corresponding one of the three arrays. Thus, the first and second adhering portions <b>61</b>, <b>62</b> are uniformly distributed and accordingly the ink jet printer head <b>1</b> can enjoy a high adhesive strength of each ejector unit <b>6</b>.

[0050] Opposite ends of each of the three arrays of first adhering portions <b>61</b><i>a</i>, <b>61</b><i>b </i>are located outside opposite ends of a corresponding one of the three arrays of second adhering portions <b>62</b><i>a</i>, <b>62</b><i>b</i>, respectively. That is, the length La of each array of first adhering portions <b>61</b><i>a</i>, <b>61</b><i>b </i>in the direction parallel to the arrays P of nozzles <b>54</b> is greater than the length Lb of each array of second adhering portions <b>62</b><i>a</i>, <b>62</b><i>b</i>, so that the each array of first adhering portions <b>61</b><i>a</i>, <b>61</b><i>b </i>extends over the opposite ends of the corresponding array of second adhering portions <b>62</b><i>a</i>, <b>62</b><i>b</i>. Thus, the first adhering portions <b>61</b> are widely distributed in the three arrays parallel to the arrays P of nozzles <b>54</b>, and accordingly the two ejector units <b>6</b> can be strongly fixed to the cover plate <b>44</b>.

[0051] Next, there will be described a construction of each ejector unit <b>6</b> by reference to FIGS. 9 through 14. As described above, each ejector unit <b>6</b> includes the cavity plate <b>10</b>, the nozzle sheet <b>43</b>, the piezoelectric actuator <b>20</b>, and the flexible flat cable <b>40</b>. The cavity plate <b>10</b> is provided by a plurality of metallic sheets that are stacked on each other. The nozzle sheet <b>43</b> is fixed, by adhesion, to a lower surface of the cavity plate <b>10</b>. The piezoelectric actuator <b>20</b> is a sheet-stacked-type one that is provided by a plurality of piezoelectric sheets that are stacked on each other, and is stacked on, and fixed with adhesive or an adhesive sheet to, an upper surface of the cavity plate <b>10</b>. The flexible flat cable <b>40</b> is provided on an upper surface of the piezoelectric actuator <b>20</b>.

[0052] The flexible flat cable <b>40</b> has various wiring patterns that are electrically connected to first and second surface electrodes <b>30</b>, <b>31</b> of the piezoelectric actuator <b>20</b>, as shown in FIG. 9, and is electrically connected to an external device, not shown. The first and second surface electrodes <b>30</b>, <b>31</b> of the piezoelectric actuator <b>20</b> will be described later.

[0053] In FIG. 10, the nozzle sheet <b>43</b> is provided by a thin sheet formed of a synthetic resin, and is adhered to a central portion of the lower surface of the cavity plate <b>10</b>. The nozzle sheet <b>43</b> has the plurality of nozzles <b>54</b> that are arranged in two arrays in a staggered or zigzag fashion in a lengthwise direction of the sheet <b>43</b>. The ejector unit <b>6</b> ejects a droplet of ink in a downward direction from each of the nozzles <b>54</b>. The nozzle sheet <b>43</b> has two positioning holes <b>55</b> that are formed through the thickness of two opposite end portions thereof, respectively. The manner in which the positioning holes <b>55</b> are used will be described later.

[0054] As shown in FIG. 10, the cavity plate <b>10</b> includes a bottom sheet <b>11</b>, two manifold sheets <b>12</b>, a spacer sheet <b>13</b>, and a base sheet <b>14</b>. Those sheets are provided by, e.g., thin metallic sheets and are stacked on, and adhered by adhesion to, each other.

[0055] The bottom sheet <b>11</b> has a lower surface to which the nozzle sheet <b>43</b> is adhered, and an upper surface to which the lower one of the two manifold sheets <b>12</b> is adhered. The lower manifold sheet <b>12</b> has two first ink passages <b>12</b><i>a </i>that are formed in an upper surface thereof and open in the upper surface only and respectively extend on opposite sides of two arrays of through-holes <b>17</b> thereof that are opposite to each other in a widthwise direction thereof. The upper manifold sheet <b>12</b> has two second ink passages <b>12</b><i>b </i>that are formed through the thickness thereof and respectively extend on opposite sides of two arrays of through-holes <b>17</b> thereof that are opposite to each other in a widthwise direction thereof. The two first ink passages <b>12</b><i>a </i>and the two second ink passages <b>12</b><i>b </i>cooperate with each other to provide two common ink manifolds <b>12</b><i>a</i>, <b>12</b><i>b</i>; <b>12</b><i>a</i>, <b>12</b><i>b</i>, respectively. Respective upper openings of the two common ink manifolds <b>12</b><i>a</i>, <b>12</b><i>b</i>; <b>12</b><i>a</i>, <b>12</b><i>b </i>are closed by the spacer sheet <b>13</b>. The bottom sheet <b>11</b> has two positioning holes <b>56</b><i>a </i>that are formed through the thickness of two lengthwise opposite end portions thereof, respectively, and are aligned with the two positioning holes <b>55</b> of the nozzle sheet <b>43</b>, respectively; and the lower manifold sheet <b>12</b> has two positioning holes <b>56</b><i>b </i>that are formed through the thickness of two lengthwise opposite end portions thereof, respectively, and are aligned with the two positioning holes <b>55</b> of the nozzle sheet <b>43</b>, respectively, and the two positioning holes <b>56</b><i>a </i>of the bottom sheet <b>11</b>, respectively.

[0056] The spacer sheet <b>13</b> has two ink-supply holes <b>19</b><i>a </i>that are formed through the thickness of one of lengthwise opposite end portions thereof and communicate with respective one end portions of the two common ink manifolds <b>12</b><i>a</i>, <b>12</b><i>b</i>; <b>12</b><i>a</i>, <b>12</b><i>b</i>; and the base sheet <b>14</b> has two ink-supply holes <b>19</b><i>b </i>that are formed through the thickness of one of lengthwise opposite end portions thereof and communicate with the respective one end portions of the two common ink manifolds <b>12</b><i>a</i>, <b>12</b><i>b</i>; <b>12</b><i>a</i>, <b>12</b><i>b </i>via the two ink supply holes <b>19</b><i>a </i>of the spacer sheet <b>13</b>. In a state in which the two ejector units <b>6</b> are assembled with the frame member <b>2</b>, the four ink supply holes <b>19</b><i>b</i>, in total, of the two ejector units <b>6</b> are held in contact with the four packing members <b>47</b>, respectively, and communicate with the four ink supply passages <b>4</b><i>a</i>-<b>4</b><i>d </i>of the frame member <b>2</b>, respectively. The ink supply holes <b>19</b><i>b </i>of the base sheet <b>14</b> are equipped with a filter member <b>29</b> that removes dust from the inks supplied from the ink tanks, not shown. The filter member <b>29</b> is adhered with adhesive to the upper surface of the base sheet <b>14</b>.

[0057] The base sheet <b>14</b> has a plurality of elongate pressure chambers <b>16</b> that are arranged in two arrays in a zigzag manner in a lengthwise direction of the sheet <b>14</b>. Each of the pressure chambers <b>16</b> extends from a widthwise middle portion of the base sheet <b>14</b> toward a widthwise end portion of the same <b>14</b>.

[0058] An inner end portion <b>16</b><i>a </i>of each of the pressure chambers <b>16</b> communicates with a corresponding one of the nozzles <b>54</b> via a corresponding one of through-holes <b>17</b><i>b </i>formed through the thickness of the spacer sheet <b>13</b>, a corresponding one of the through-holes <b>17</b><i>a </i>formed through the thickness of the upper manifold sheet <b>12</b>, a corresponding one of the through-holes <b>17</b><i>a </i>formed through the thickness of the lower manifold sheet <b>12</b>, and a corresponding one of through-holes <b>15</b> formed through the thickness of the bottom sheet <b>11</b>. An outer end portion <b>16</b><i>b </i>of each pressure chamber <b>16</b> communicates with a corresponding one of the two common ink manifolds <b>12</b><i>a</i>, <b>12</b><i>b</i>; <b>12</b><i>a</i>, <b>12</b><i>b </i>via a corresponding one of communication holes <b>18</b> formed through the thickness of the spacer sheet <b>13</b>.

[0059] In the ink jet printer head <b>1</b> constructed as described above, the four inks supplied through the four ink supply passages <b>4</b><i>a</i>-<b>4</b><i>d </i>flow to the four common ink manifolds <b>12</b><i>a</i>, <b>12</b><i>b </i>of the two ejector units <b>6</b> via the four ink supply holes <b>19</b><i>b </i>of the two base sheets <b>14</b> and the four ink supply holes <b>19</b><i>a </i>of the two spacer sheets <b>13</b>, respectively, and then flow from the four ink manifolds <b>12</b><i>a</i>, <b>12</b><i>b </i>to the respective outer end portions <b>16</b> of the four arrays of pressure chambers <b>16</b> of the two base sheets <b>14</b> via the four arrays of communication holes <b>18</b> of the two spacer sheets <b>12</b>. The ink flowing from the inner end portion <b>16</b><i>a </i>of each pressure chamber <b>16</b> reaches a corresponding one of the four arrays of nozzles <b>54</b> of the two nozzle sheets <b>43</b> via a corresponding one of the four arrays of through-holes <b>17</b><i>b </i>of the two spacer sheets <b>13</b>, a corresponding one of the four arrays of through-holes <b>17</b><i>a </i>of the two upper manifold sheets <b>12</b>, a corresponding one of the four arrays of through-holes <b>17</b><i>a </i>of the two lower manifold sheets <b>12</b>, and a corresponding one of the four arrays of through-holes <b>15</b> of the two bottom sheets <b>11</b>.

[0060] As shown in FIG. 13, the piezoelectric actuator <b>20</b> has a structure in which a plurality of (e.g., nine) piezoelectric sheets <b>21</b><i>a</i>, <b>21</b><i>b</i>, <b>21</b><i>c</i>, <b>21</b><i>d</i>, <b>21</b><i>e</i>, <b>21</b><i>f</i>, <b>21</b><i>g</i>, <b>22</b>, <b>23</b> are stacked on each other. On an upper surface of each of the lowermost piezoelectric sheet <b>22</b> and the third, fifth, and seventh piezoelectric sheets <b>21</b><i>b</i>, <b>21</b><i>d</i>, <b>21</b><i>f </i>as counted in an upward direction from the lowermost sheet <b>22</b>, there are provided a plurality of elongate proper individual electrodes <b>24</b> which are aligned with the pressure chambers <b>16</b> of the cavity plate <b>10</b>, respectively, and are arranged in two arrays in a zigzag fashion in a lengthwise direction of the each piezoelectric sheet <b>22</b>, <b>21</b><i>b</i>, <b>21</b><i>d</i>, <b>21</b><i>f. </i>

[0061] In addition, on an upper surface of each of the second, fourth, sixth, and eighth piezoelectric sheets <b>21</b><i>a</i>, <b>21</b><i>c</i>, <b>21</b><i>e</i>, <b>21</b><i>g </i>as counted in the upward direction from the lowermost sheet <b>22</b>, there is provided a proper common electrode <b>25</b> which is aligned commonly to all the pressure chambers <b>16</b>.

[0062] Moreover, on an upper surface of the uppermost piezoelectric sheet <b>23</b>, there are provided a plurality of first surface electrodes <b>30</b> which are arranged in two arrays in widthwise opposite edge portions of the sheet <b>23</b> along two long sides thereof, and are aligned, in their plan view, with the proper individual electrodes <b>24</b>, respectively, provided on each of the four sheets <b>22</b>, <b>21</b><i>b</i>, <b>21</b><i>d</i>, <b>21</b><i>f</i>, and four second surface electrodes <b>31</b> which are aligned with two lead portions <b>25</b><i>a </i>of each of the four common electrodes <b>25</b>. The first surface electrodes <b>30</b> and the proper individual electrodes <b>24</b> are electrically connected to each other via an electrically conductive material provided in through-holes <b>32</b> that are formed through the thickness of each of the sheets <b>21</b><i>a</i>-<b>21</b><i>g </i>and <b>23</b> and a plurality of dummy individual electrodes <b>26</b> provided on each of the second, fourth, and sixth sheets <b>21</b><i>a</i>, <b>21</b><i>c</i>, <b>21</b><i>e</i>, <b>21</b><i>g</i>; and, likewise, the second surface electrodes <b>31</b> and the proper common electrodes <b>25</b> (or the lead portions <b>25</b><i>a </i>thereof) are electrically connected to each other via an electrically conductive material provided in through-holes <b>33</b> that are formed through the thickness of each of the sheets <b>21</b><i>a</i>-<b>21</b><i>g </i>and <b>23</b> and a plurality of dummy common electrodes <b>27</b> provided on each of the lowermost sheet <b>22</b> and the third, fifth, and seventh sheets <b>21</b><i>b</i>, <b>21</b><i>d</i>, <b>21</b><i>f</i>. As described previously, the wiring patterns of the flexible flat cable <b>40</b> (FIG. 1) are electrically connected to the surface electrodes <b>30</b>, <b>31</b> provided on the upper surface of the piezoelectric actuator <b>20</b>.

[0063] Since each ejector unit <b>6</b> has the above-described construction, when an electric voltage is applied to the common electrodes <b>25</b> and the respective individual electrodes <b>24</b> on the piezoelectric sheets <b>22</b>, <b>21</b><i>b</i>, <b>21</b><i>d</i>, <b>21</b><i>f </i>that are aligned with an arbitrary one of the pressure chambers <b>16</b>, respective portions of the piezoelectric sheets <b>21</b><i>a</i>-<b>21</b><i>g </i>that are aligned with the arbitrary pressure chamber <b>16</b> are deformed, by piezoelectric effect, in a direction of stacking of the sheets <b>21</b><i>a</i>-<b>21</b><i>g</i>, <b>22</b>, <b>23</b>. This deformation decreases a volume of the arbitrary pressure chamber <b>16</b>, so that a droplet of ink accommodated in the chamber <b>16</b> is ejected from the nozzle <b>54</b> communicating with the same <b>16</b>, toward the recording sheet so as to record an image.

[0064] Next, there will be described a method of producing an ink jet printer head <b>1</b> by adhering a plurality of (e.g., two) ejector units <b>6</b>, a cover plate <b>44</b>, and a frame member <b>2</b> to each other.

[0065] In FIG. 15, first, the cover plate <b>44</b> is placed on a jig plate <b>42</b> as a support member, while the cover plate <b>44</b> is taking a posture in which the bent portions <b>44</b><i>b</i>, <b>44</b><i>c </i>thereof project upward. More specifically described, the jig plate <b>42</b> has two flat lands <b>41</b> each of which is somewhat smaller than each of the two first openings <b>44</b><i>a </i>of the cover plate <b>44</b>, and the cover plate <b>44</b> is positioned relative to the jig plate <b>42</b> such that the two lands <b>41</b> are received in the two first openings <b>44</b><i>a</i>, respectively. In this state, the sealing agent <b>60</b> is applied to a periphery of each first opening <b>44</b><i>a </i>of the cover plate <b>44</b>, as indicated at hatching in FIG. 16A.

[0066] Subsequently, as shown in FIG. 16B, the two ejector units <b>6</b>, each of which includes the nozzle sheet <b>43</b>, the cavity plate <b>10</b>, the piezoelectric actuator <b>20</b>, and the flexible flat cable <b>40</b> that are assembled with each other, are placed on the cover plate <b>44</b>. Each of the two lands <b>41</b>, respectively exposed through the two first openings <b>44</b><i>a</i>, has two positioning pins <b>41</b><i>a</i>, and each of the two ejector units <b>6</b> is placed on the cover plate <b>44</b>, such that the two positioning pins <b>41</b><i>a </i>are inserted in the positioning holes <b>55</b>, <b>56</b><i>a</i>, <b>56</b><i>b </i>of the each ejector unit <b>6</b>. Thus, the two ejector units <b>6</b> are positioned relative to the cover plate <b>44</b>, such that the nozzles <b>54</b> of one of the two ejector units <b>6</b> are accurately positioned relative to the nozzles <b>54</b> of the other ejector unit <b>6</b>. In this state, the sealing agent <b>60</b> is provided, between the upper surface of the cover plate <b>44</b> and the respective lower surfaces of the two ejector units <b>6</b>, around the two first openings <b>44</b><i>a</i>, such that the nozzles <b>54</b> of the two ejector units <b>6</b> are exposed downward through the two first openings <b>44</b><i>a</i>, respectively.

[0067] Next, as shown in FIG. 16C, in a state in which the sealing agent <b>60</b> has not been hardened yet, a pressing member <b>63</b> is operated by an operator to press, in a downward direction, the two ejector units <b>6</b> against the cover plate <b>44</b>, so that the ejector units <b>6</b> and the cover plate <b>44</b> cannot be moved relative to each other. In this state, a first adhering step is carried out in which the two ejector units <b>6</b> and the cover plate <b>44</b> are adhered and fixed to each other using the first adhesive. The pressing member <b>63</b> includes two pressing portions <b>63</b><i>a </i>that act on the two ejector units <b>6</b>, respectively, and a handle portion <b>63</b><i>b </i>that is grasped by the operator.

[0068] As shown in FIG. 16D, in the first adhering step, a dispenser in the form of a hollow needle, not shown, (this dispenser is identical with a dispenser used to apply the second adhesive, described later) is used to apply the first adhesive (i.e., an UV-light sensitive adhesive) in the form of spots arranged at a substantially regular interval of distance along widthwise opposite edge portions of the respective cavity plates <b>10</b> that constitute respective exposed portions of the two ejector units <b>6</b>, i.e., in the lengthwise direction of the cavity plates <b>10</b>. When the first adhesive is hardened upon exposure to UV light, the first adhesive portions <b>61</b><i>a</i>, <b>61</b><i>b</i>, described above in connection with the construction of the ink jet printer head <b>1</b>, are formed. After the first adhesive portions <b>61</b><i>a</i>, <b>61</b><i>b </i>are formed by hardening the first adhesive, the pressing member <b>63</b> is released from the two ejector units <b>6</b>. Thus, as shown in FIG. 16E, a subassembly including the two ejector units <b>6</b> and the cover plate <b>44</b> that are adhered and fixed to each other with the first adhesive portions <b>61</b><i>a</i>, <b>61</b><i>b </i>is obtained.

[0069] In the above-described first adhering step, the first adhesive portions <b>61</b> are formed in the state in which the two ejector units <b>6</b> are pressed against the cover plate <b>44</b> by the pressing member <b>63</b>, even though the sealing agent <b>60</b> provided between the ejector units <b>6</b> and the cover plate <b>44</b> may not have been hardened yet. Therefore, the ejector units <b>6</b> and the cover plate <b>44</b> can be fixed in position relative to each other. Thus, the present step is free of the problems that the ejector units <b>6</b> and the cover plate <b>44</b> may be moved relative to each other and the sealing agent <b>60</b> flows or moves and that sealing defects such as bubbles or uneven sealing may occur to the sealing portions provided by the sealing agent <b>60</b>.

[0070] On the other hand, if the pressing member <b>63</b> is used to press the two ejector units <b>6</b> to the cover plate <b>44</b> via the sealing agent <b>60</b>, so that the ejector units <b>6</b> and the cover plate <b>44</b> are once held in close contact with each other, but thereafter the pressing member <b>63</b> is released from the ejector units <b>6</b>, without carrying out the above-described first adhering step, the ejector units <b>6</b> and the cover plate <b>44</b> can easily be moved relative to each other, and accordingly gaps may easily be produced, because the sealing agent <b>60</b> has not been hardened yet. In addition, the sealing agent <b>60</b> can easily be flowed or moved and accordingly can easily be distributed unevenly like waves. Therefore, the above-explained defects can easily occur. It is possible to continue pressing, with the pressing member <b>63</b>, the ejector units <b>6</b> against the cover plate <b>44</b>, till the sealing agent <b>60</b> is completely hardened. However, generally, the speed of hardening of the sealing agent <b>60</b> is considerably low, and accordingly the efficiency of production of the ink jet printer head <b>1</b> is lowered. In contrast, in the present producing method, the first adhering step is carried out, and accordingly the ejector units <b>6</b> and the cover plate <b>44</b> can be surely adhered and fixed to each other, irrespective of the degree of hardening of the sealing agent <b>60</b>. Thus, the defects of the sealing agent <b>60</b> can be surely prevented without lowering the efficiency of production of the ink jet printer head <b>1</b>.

[0071] As shown in FIG. 17A, after the first adhering step is finished, the frame member <b>2</b> is placed on the subassembly including the two head units <b>6</b> and the cover plate <b>44</b>, such that the two ejector units <b>6</b> are accommodated in a recess <b>5</b><i>a </i>formed in the bottom wall <b>5</b> of the frame member <b>2</b>.

[0072] As shown in FIG. 17B, after the frame member <b>2</b> is placed on the subassembly <b>6</b>, <b>44</b>, a dispenser <b>64</b> in the form of a hollow needle is used to inject the second adhesive (i.e., a UV-light sensitive adhesive) into the second openings <b>9</b><i>a</i>, <b>9</b><i>b </i>of the frame member <b>2</b>. After an appropriate amount of the second adhesive is charged into each of the second openings <b>9</b><i>a</i>, <b>9</b><i>b</i>, the second adhesive is hardened upon exposure to an UV light and thus the second adhesive portions <b>62</b>, shown in FIG. 6, are formed. In this way, the subassembly including the two ejector units <b>6</b> and the cover plate <b>44</b> is adhered and fixed to the bottom wall <b>5</b> of the frame member <b>2</b>, and thereafter the ink jet printer head <b>1</b> is removed off the jig plate <b>41</b>. Then, the sealing agent <b>45</b> is charged into clearances left between an outer periphery of the cover plate <b>44</b> and the frame member <b>2</b>.

[0073] As is apparent from the foregoing description, the ink jet printer head <b>1</b> and the method of producing the same <b>1</b> can improve the adhesive strength of the ejector units <b>6</b> and can effectively prevent the defects of the sealing portions provided by the sealing agent <b>60</b> interposed between the ejector units <b>6</b> and the cover plate <b>44</b>.

[0074] While the present invention has been described in its preferred embodiment, it is to be understood that the present invention may otherwise be embodied.

[0075] For example, the bottom wall <b>5</b> of the frame member <b>2</b> may not have any second openings <b>9</b>. In this case, the frame member <b>2</b> is placed over the subassembly including the ejector units <b>6</b> and the cover plate <b>44</b>, such that the second adhesive is interposed between the subassembly <b>6</b>, <b>44</b> and the frame member <b>2</b> so as to adhere the two elements to each other. Thus, the second adhesive portions <b>62</b> are formed of the second adhesive.

[0076] In addition, the first adhesive portions <b>61</b> may not include any portions that are not aligned, in their plan view, with the second openings <b>9</b>. Moreover, the first and second adhesive portions <b>61</b>, <b>62</b> may not be formed as described previously, i.e., such that they are arranged at the respective substantially regular intervals of distance, in the mixed arrays substantially parallel to the arrays of nozzles <b>54</b>. Furthermore, the opposite end portions of the arrays of first adhesive portions <b>61</b> may not be located outside the opposite ends of the corresponding arrays of second adhesive portions <b>62</b>.

[0077] The ink jet printer head <b>1</b> may be modified not to include the two ejector units <b>6</b>, i.e., may be modified to include a single ejector <b>6</b> or three or more ejector units <b>6</b>. In addition, the respective total numbers of the second openings <b>9</b>, the first adhesive portions <b>61</b>, and the second adhesive portions <b>62</b> may be arbitrarily selected.

[0078] For example, FIGS. 18A and 18B show another ink jet printer head <b>101</b> as another embodiment of the present invention. The present ink jet printer head <b>101</b> includes a frame member <b>102</b> including a bottom wall <b>105</b>; four ejector units <b>106</b> including respective cavity plates <b>110</b>; and five arrays of second openings <b>109</b> each array of which includes five second openings <b>109</b>. FIG. 18A shows one array of second openings <b>109</b> in which a second adhesive has not been injected yet; and FIG. 18B shows a subassembly including the four ejector units <b>106</b> and a cover plate <b>144</b> having four first openings <b>144</b><i>a</i>. The five arrays of second openings <b>109</b> are formed in the bottom wall <b>105</b> of the frame member <b>102</b>, such that the five arrays of second openings <b>109</b> are arranged along respective edge lines of the four ejector units <b>106</b> that are parallel to respective arrays of nozzles, not shown, of the same <b>106</b>. Therefore, the central, three arrays of second openings <b>109</b> are each aligned with respective edge lines of two ejector units <b>106</b> that are adjacent each other. The four ejector units <b>106</b> and the cover plate <b>144</b> are adhered to each other by five arrays of first adhesive portions <b>161</b> (<b>161</b><i>a</i>, <b>161</b><i>b</i>) each array of which includes a plurality of separate first adhesive portions <b>161</b>. However, each array of first adhesive portions <b>161</b> may be replaced with a single continuous first adhesive portion. A total length La of each array of first adhesive portions <b>161</b> is longer than a total length Lb of each array of second openings <b>109</b>, and accordingly respective opposite end portions of each array of first adhesive portions <b>161</b> are not aligned, in their plan view, with the corresponding array of second openings <b>109</b>. Five arrays of second adhesive portions, not shown, are formed by hardening of the second adhesive injected in the second openings <b>109</b>.

[0079] Each of the first and second adhesives may be different from the UV-light sensitive adhesive. In this case, too, it is preferred that the first adhesive be hardened more quickly than the sealing agent.

[0080] Each ejector unit <b>6</b>, <b>106</b> may be replaced with any sort of ejector unit that has, in an outer surface thereof that opposes a recording medium, a plurality of nozzles each of which ejects a droplet of ink toward the recording medium. That is, the cavity plate <b>10</b>, <b>110</b>, the piezoelectric actuator <b>20</b>, the nozzle sheet <b>43</b>, and the flexible flat cable <b>40</b> of each ejector unit <b>6</b>, <b>106</b> may be modified in various manners.

[0081] In each of the illustrated embodiments, the frame member <b>2</b>, <b>102</b> has at least one second opening <b>9</b>, <b>109</b> which is formed through the thickness of the bottom wall <b>5</b>, <b>105</b> thereof and is opposed to at least one portion of the subassembly <b>6</b>, <b>44</b>; <b>106</b>, <b>144</b> in a reference direction perpendicular to the bottom wall <b>5</b>, <b>105</b>, and at least one second adhering portion <b>62</b> is aligned with at least one second opening <b>9</b>, <b>109</b> in the reference direction. According to this feature, the second adhering portion <b>62</b> can be formed by just pouring the second adhesive into the second opening <b>9</b>, <b>109</b>, in the state in which the subassembly including the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b>, and the frame member <b>2</b>, <b>102</b> are positioned relative to each other. Thus, the subassembly including the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> can be easily adhered and fixed to the bottom wall <b>5</b>, <b>105</b> of the frame member <b>2</b>, <b>102</b>.

[0082] In each of the illustrated embodiments, at least one first adhering portion <b>61</b>, <b>161</b> comprises at least one non-alignment first adhering portion which is not aligned with at least one second opening <b>9</b>, <b>109</b> of the bottom wall <b>5</b>, <b>105</b> of the frame member <b>2</b>, <b>102</b> in the reference direction. According to this feature, the ejector unit <b>6</b>, <b>106</b> and the cover plate <b>44</b>, <b>144</b> can be adhered and fixed to each other by the non-alignment first adhering portion <b>61</b>, <b>161</b>, i.e., at the position where no second adhering portion <b>62</b> can be formed by pouring the second adhesive into the second opening <b>9</b>, <b>109</b> of the frame member <b>2</b>, <b>102</b>. Therefore, the adhesive strength of the ink jet printer head <b>1</b>, <b>101</b> can be further improved.

[0083] In each of the illustrated embodiments, the nozzles <b>54</b> of at least one ejector unit <b>6</b>, <b>106</b> are provided in at least one array P, and the ink jet printer head <b>1</b>, <b>101</b> comprises a plurality of first adhering portions <b>61</b>, <b>161</b> which are provided in at least one array along at least one reference line substantially parallel to at least one array of nozzles <b>54</b>, such that the first adhering portions <b>61</b>, <b>161</b> are arranged at a first, substantially regular interval of distance, and a plurality of second adhering portions <b>62</b> which are provided in at least one array along the reference line, such that the second adhering portions <b>62</b> are arranged at a second, substantially regular interval of distance and are mixed with the first adhering portions <b>61</b>, <b>161</b> within a predetermined range along the reference line.

[0084] In each of the illustrated embodiments, the first and second adhering portions <b>61</b>, <b>161</b>, <b>62</b> are arranged in the respective arrays, at the respective substantially regular intervals of distance, along the reference line substantially parallel to the array P of nozzles <b>54</b>, and are mixed with each other within the predetermined range along the reference line. Therefore, the components of the ink jet printer head <b>1</b>, <b>101</b> are adhered and fixed to each other at the respective positions which are substantially uniformly distributed along the array of nozzles <b>54</b>. Thus, the adhesive strength of the ink jet printer head <b>1</b>, <b>101</b> as a whole can be well balanced and still improved.

[0085] In each of the illustrated embodiments, the nozzles <b>54</b> of at least one ejector unit <b>6</b>, <b>106</b> are provided in at least one array, and at least one first adhering portion <b>61</b>, <b>161</b> is provided along at least one reference line substantially parallel to at least one array P of nozzles <b>54</b>, such that lengthwise opposite ends of at least one first adhering portion <b>61</b>, <b>161</b> are located outside lengthwise opposite ends of at least one second adhering portion <b>62</b>, respectively. According to this feature, the first adhering portion <b>61</b>, <b>161</b> that is provided along the reference line substantially parallel to the array P of nozzles <b>54</b>, has the feature that the lengthwise opposite ends thereof are located outside the lengthwise opposite ends of the second adhering portion <b>62</b>, respectively. Therefore, the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> can be more strongly fixed to each other by the first adhering portion <b>61</b>, <b>161</b> that is widely provided along the reference line.

[0086] In each of the illustrated embodiments, at least one sealing portion <b>60</b> is formed of the sealing agent, and at least one first adhering portion <b>61</b>, <b>161</b> is formed of the first adhesive which hardens more quickly than the sealing agent. According to this feature, before the sealing agent <b>60</b> provided between the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> hardens, the first adhesive constituting the first adhering portion <b>61</b>, <b>161</b> hardens, so that the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> are fixed in position relative to each other. Therefore, the ink jet printer head <b>1</b>, <b>101</b> is surely freed of the problem that the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> may be displaced relative to each other and the sealing portion <b>60</b> may suffer the sealing defects.

[0087] In each of the illustrated embodiments, the ink jet printer head <b>1</b>, <b>101</b> comprises the plurality of ejector units <b>6</b>, <b>106</b>, the cover member <b>44</b>, <b>144</b> has the plurality of first openings <b>44</b><i>a</i>, <b>144</b><i>a </i>corresponding to the ejector units <b>6</b>, <b>106</b>, respectively, and at least one adhering portion <b>61</b>, <b>161</b> adheres, and thereby fixes, the ejector units <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> to each other, such that the nozzles <b>54</b> of each one of the ejector units <b>6</b>, <b>106</b> are positioned relative to the nozzles <b>54</b> of the other ejector unit or units <b>6</b>, <b>106</b>. According to this feature, the ejector units <b>6</b>, <b>106</b> are fixed to the cover member <b>44</b>, <b>144</b>, such that the nozzles <b>54</b> of each one of the ejector units <b>6</b>, <b>106</b> are positioned relative to the nozzles <b>54</b> of the other ejector unit or units <b>6</b>, <b>16</b>. Therefore, the ejector units <b>6</b>, <b>106</b> can eject respective droplets of ink at respective accurate positions on the recording medium and thereby perform recording with high quality.

[0088] In each of the illustrated embodiments, at least one first adhering portion <b>61</b>, <b>161</b> is formed of the ultraviolet-light sensitive adhesive which hardens upon exposure to the ultraviolet light. According to this feature, the first adhering portion <b>61</b>, <b>161</b> is constituted by the ultraviolet-light sensitive adhesive which hardens upon exposure to the ultraviolet light. Therefore, the first adhering portion <b>61</b>, <b>161</b> can be quickly hardened in a very short time. Thus, the ink jet printer head <b>1</b>, <b>101</b> is surely freed of the defects that may be produced between the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b>.

[0089] In each of the illustrated embodiments, at least one second adhering portion <b>62</b> is formed of the ultraviolet-light sensitive adhesive which hardens upon exposure to the ultraviolet light. According to this feature, the second adhering portion is constituted by the ultraviolet-light sensitive adhesive which hardens upon exposure to the ultraviolet light. Therefore, the second adhering portion <b>62</b> can be quickly hardened in a very short time.

[0090] In each of the illustrated embodiments, the sealing portion <b>60</b> is formed of the sealing agent, and the sealing agent comprises the silicone adhesive. According to this feature, the sealing portion <b>60</b> is constituted by the silicone adhesive. Therefore, the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> are not only fluid-tightly sealed to each other but also adhered to each other. Thus, the sealing portion <b>60</b> can be easily provided in the form of a layer between the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b>.

[0091] In each of the illustrated embodiments, the ink jet printer head producing method comprises the step of preparing the frame member <b>2</b>, <b>102</b> having at least one second opening <b>9</b>, <b>109</b> which is formed through the thickness of the bottom wall <b>5</b>, <b>105</b> thereof, and the step of adhering with the second adhesive comprises applying, through the second opening <b>9</b>, <b>109</b> of the frame member <b>2</b>, <b>102</b>, the second adhesive to at least one portion of the subassembly <b>6</b>, <b>44</b>; <b>106</b>, <b>144</b>. According to this feature, the subassembly including the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b>, and the frame member <b>2</b>, <b>102</b> can be adhered and fixed to each other, by just pouring the second adhesive into the second opening <b>9</b>, <b>109</b>, in the state in which the subassembly <b>6</b>, <b>44</b>; <b>106</b>, <b>144</b> and the frame member <b>2</b>, <b>102</b> are positioned relative to each other. Thus, the subassembly including the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> can be easily adhered and fixed to the bottom wall <b>5</b>, <b>105</b> of the frame member <b>2</b>, <b>102</b>.

[0092] In each of the illustrated embodiments, the step of adhering with the first adhesive comprises adhering, with the first adhesive, at least one ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b> to each other at at least one portion that is not aligned with the second opening <b>9</b>, <b>109</b> of the bottom wall <b>5</b>, <b>105</b> of the frame member <b>2</b>, <b>102</b>, in a reference direction perpendicular to the bottom wall <b>5</b>, <b>105</b> of the frame member <b>2</b>, <b>102</b>. According to this feature, the ejector unit <b>6</b>, <b>106</b> and the cover plate <b>44</b>, <b>144</b> can be adhered and fixed to each other at the respective non-alignment portions thereof, i.e., at the positions where no second adhering portion <b>62</b> can be formed by pouring the second adhesive into the second opening <b>9</b>, <b>109</b> of the frame member <b>2</b>, <b>102</b>. Therefore, the adhesive strength of the ink jet printer head <b>1</b>, <b>101</b> can be further improved.

[0093] In each of the illustrated embodiments, at least one first adhering portion <b>61</b>, <b>161</b> is continuously formed on respective exposed portions of at least one ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b>. According to this feature, an adhesive can be easily applied to the respective exposed portions of the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b>, and can be quickly hardened upon exposure to, e.g., an UV light. In contrast, since the sealing portion or agent <b>60</b> is provided between the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b>, the sealing portion or agent <b>60</b> is not exposed and accordingly the UV light cannot be used to harden quickly the sealing agent <b>60</b>.

[0094] In each of the illustrated embodiments, the ink jet printer head <b>1</b>, <b>101</b> comprises the plurality of first adhering portions <b>61</b>, <b>161</b> which are formed in two arrays along widthwise opposite edge lines of at least one ejector unit <b>6</b>, <b>106</b>, such that each of the first adhering portions <b>61</b>, <b>161</b> is continuously formed on the respective exposed portions of the ejector unit <b>6</b>, <b>106</b> and the cover member <b>44</b>, <b>144</b>. According to this feature, the ejector unit <b>6</b>, <b>106</b> is fixed to the cover member <b>44</b>, <b>144</b> with a great adhesive strength.

[0095] It is to be understood that the present invention may be embodied with various changes and improvements that may occur to a person skilled in the art, without departing from the spirit and scope of the invention defined in the appended claims.