JP2008068500A - Liquid jet head and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance ejection performance by avoiding the problem of warpage caused by variation of temperature, moisture or the like of the environment even when a material of a nozzle plate is different from that of a pressurizing chamber plate. <P>SOLUTION: The nozzle plate 21 comprises a plurality of nozzles 51 passing through the nozzle plate 21 and communicating with pressurizing chambers 52, and a recess 30 which is formed at the periphery of each of the nozzles 51 to pass through the nozzle plate 21 and allows the pressurizing chamber plate 22 to be exposed. The plurality of recesses 30 are arranged on each closed curve surrounding each nozzle 51. Alternately, the plurality of recesses 30 are arranged on each closed curve surrounding a nozzle group including the plurality of nozzles 51. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid discharge head and a manufacturing method thereof, and more particularly to a liquid discharge head formed by joining a nozzle plate to a pressure chamber plate and a manufacturing method thereof.

  When the nozzle plate in which the nozzles are formed and the pressure chamber plate in which the pressure chambers are formed are bonded, generally, an adhesive, diffusion bonding, eutectic bonding, metal welding, anodic bonding, or the like is used.

  In Patent Document 1, the total number of nozzles to be processed on one nozzle plate is set as a task to efficiently and accurately process a plurality of nozzles simultaneously. What is processed so that it may satisfy | fill is satisfy | filled.

  Japanese Patent Application Laid-Open No. H10-228667 describes a technique in which an alignment mark is attached to a nozzle plate and a counterpart base material, and these are positioned together.

  Patent Document 3 describes a nozzle member stored at a temperature and humidity to be bonded and fixed so as to avoid the problem of thermal expansion during bonding.

  Japanese Patent Application Laid-Open No. H10-228667 describes a nozzle hole that is accurately opened after a plate serving as a nozzle plate is bonded to a substrate.

Patent Document 5 describes a nozzle plate that is bonded to a substrate using a nozzle support member.
JP 2001-322281 A JP 2002-96473 A Japanese Patent Laid-Open No. 2003-276205 JP 2005-131950 A JP 2003-246069 A

  In a liquid discharge head in which the nozzle plate is joined to the pressure chamber plate, if the processing temperature and operating temperature are different, the nozzle plate warps due to the difference in thermal expansion coefficient between the nozzle plate and the pressure chamber plate. There is a problem that deformation occurs. In order to avoid the problem of thermal expansion at the time of joining the nozzle plate and the pressure chamber plate (described in Patent Document 3), if the temperature and humidity change in the use environment after joining, the nozzle plate There is a problem that warpage deformation occurs on the whole, the ejection direction of the ink droplets ejected from each nozzle is shifted, and the landing position accuracy is deteriorated.

  The present invention has been made in view of such circumstances, and even if the material of the nozzle plate is different from the material of the pressure chamber plate, it avoids the problem of warping caused by changes in the temperature and humidity of the use environment. An object of the present invention is to provide a liquid discharge head having good discharge performance and a method for manufacturing the same.

  In order to achieve the above object, the invention according to claim 1 includes a pressure chamber plate in which a pressure chamber filled with liquid is formed, and a nozzle plate joined to the pressure chamber plate. The nozzle plate includes a plurality of nozzles that pass through the nozzle plate and communicate with the pressure chamber, and a recess that is formed around the nozzle and exposes the pressure chamber plate through the nozzle plate. A liquid discharge head is provided.

  According to the present invention, since the pressure chamber plate is exposed in the recess around the nozzle and the dissimilar material is not joined, distortion due to the difference in thermal expansion is not accumulated, and the nozzle of the nozzle is not used in the usage environment. The stress generated around is relieved at the recess. Therefore, even if the structure of the nozzle edge is low, the nozzle does not undergo an undesirable shape change due to the stress generated around the nozzle, and is dedicated to the desired shape change for ejection. As a result, it is possible to discharge with high accuracy of the landing position.

  According to a second aspect of the present invention, in the first aspect of the invention, a plurality of the recesses are arranged on each closed curve surrounding the plurality of nozzles for each nozzle. I will provide a.

  According to this invention, stress relaxation can be achieved for each nozzle individually.

  According to a third aspect of the present invention, in the second aspect of the present invention, a plurality of the concave portions are arranged on a plurality of concentric closed curves surrounding the plurality of nozzles for each nozzle, and are on a different concentric closed curve. Provided is a liquid discharge head characterized in that the concave portions are arranged in a staggered manner so as to be staggered.

  According to the present invention, since the recesses are formed in a staggered pattern around the nozzle, a large stress relaxation effect can be expected.

  According to a fourth aspect of the present invention, there is provided the liquid according to the first aspect of the invention, wherein the symmetry axis of the shape of the concave portion and the arrangement pattern coincides with the symmetry axis of the opening shape of the nozzle. A discharge head is provided.

  According to this invention, not only when the opening shape of the nozzle is a circular shape, but also when the shape is a polygonal shape or a star shape, stress relaxation can be performed without impairing the symmetry of the nozzle shape.

  The invention according to claim 5 is the invention according to claim 4, wherein the opening shape of the nozzle is a regular polygon, and the plurality of concave portions are positive shapes having the opening shape of the nozzle for each nozzle. Provided is a liquid discharge head characterized in that it is formed in a symmetrical pattern with respect to a bisector of each internal angle of the polygon and symmetrical with respect to a perpendicular bisector of each side of the regular polygon. .

  The invention according to claim 6 is the invention according to claim 4, wherein the opening shape of the nozzle is a star-shaped regular polygon, and the plurality of recesses have the opening shape of the nozzle for each nozzle. Provided is a liquid discharge head characterized by being formed in a symmetrical pattern with respect to a bisector of each inner angle of a certain star-shaped regular polygon.

  According to a seventh aspect of the present invention, in the first aspect of the present invention, a plurality of the recesses are arranged on each closed curve surrounding the plurality of nozzles for each nozzle group. Provide the head.

  According to this invention, by separating each nozzle group, it is possible to expect the effect of preventing warpage of the nozzle surface and the effect of maintaining rigidity.

  According to an eighth aspect of the present invention, there is provided the liquid ejection head according to the first aspect, wherein the recess is formed so as to draw a closed curve surrounding the nozzle.

  According to the present invention, since the recess itself forms a closed curve, a large stress relaxation effect can be expected.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the nozzle plate has a row of through holes or grooves that divide the entire surface of the nozzle plate into a plurality of divided areas. Provided is a liquid discharge head which is formed.

  According to the present invention, since the entire surface of the nozzle plate is divided into a plurality of divided areas by the through-hole rows or grooves, the distortion is prevented from being transmitted at the boundaries of the divided areas, and the distortion on the entire surface of the nozzle surface is a constant value. Thus, the phenomenon of warping of the entire liquid discharge head can be reduced.

  According to a tenth aspect of the present invention, there is provided the liquid discharge head according to any one of the first to ninth aspects, wherein the nozzle has a tapered shape.

  In discharging a highly viscous liquid, the liquid column is usually not easily torn due to the influence of viscosity at the time of discharging, and it is difficult to form fine droplets. According to the present invention, by forming the nozzle in a taper shape, the edge of the nozzle is bent when the pressure (liquid column formation) to negative pressure (droplet formation) in the liquid ejection head is performed, and the diameter is reduced. The effect of squeezing after spreading is obtained, and the effect of contributing to tearing of the droplets is obtained. Note that the edge of a nozzle having a tapered shape is soft and low in rigidity, but since a recess is formed around the nozzle, the presence of this recess releases the stress around the nozzle in the recess and maintains the nozzle shape. Be drunk. Therefore, it becomes possible to discharge the high-viscosity liquid as fine droplets with high landing position accuracy.

  The invention according to claim 11 is a method of manufacturing a liquid discharge head comprising: a pressure chamber plate in which a pressure chamber filled with liquid is formed; and a nozzle plate joined to the pressure chamber plate. Forming a plurality of nozzles penetrating the nozzle plate and communicating with the pressure chamber in the nozzle plate, and a recess disposed around the nozzle and exposing the pressure chamber plate through the nozzle plate. The manufacturing method of the liquid discharge head characterized by including is provided.

  According to a twelfth aspect of the present invention, there is provided the method of manufacturing a liquid discharge head according to the eleventh aspect, wherein the recess is formed by the same formation method as the formation method of the nozzle.

  According to the present invention, since the recess is formed by the same forming method as that of the nozzle, it is possible to provide a liquid discharge head in which the recess is formed without significantly increasing the manufacturing cost as compared with the conventional manufacturing method in which the recess is not formed.

  The invention according to claim 13 is the invention according to claim 12, wherein the recess is formed in the same cross-sectional shape as the nozzle in the thickness direction of the nozzle plate and at the same time as the nozzle. A method for manufacturing a liquid discharge head according to claim 12 is provided.

  According to the present invention, since the concave portion is simultaneously formed in the same cross-sectional shape as the nozzle, a liquid discharge head in which the concave portion is formed is provided without increasing the time required for manufacturing compared with the conventional manufacturing method in which the concave portion is not formed. it can.

  According to a fourteenth aspect of the present invention, there is provided a liquid discharge apparatus comprising the liquid discharge head according to any one of the first to tenth aspects.

  According to a fifteenth aspect of the present invention, there is provided an image forming apparatus comprising the liquid discharge head according to any one of the first to tenth aspects.

  According to the present invention, even when the material of the nozzle plate is different from the material of the pressure chamber plate, it is possible to avoid the problem of warping due to changes in the temperature and humidity of the usage environment and to improve the discharge performance. . The nozzle shape is not limited to a straight shape uniform in the thickness direction of the nozzle plate, and a particularly remarkable effect is expected when the edge of the nozzle has a low rigidity structure such as a tapered shape.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Liquid discharge head]
FIG. 1 is a plan perspective view showing an overall configuration of an example of the liquid discharge head 50.

  A liquid discharge head 50 shown as an example in FIG. 1 is a so-called full-line type liquid discharge head, and is in a direction (in the drawing) orthogonal to the transport direction of the discharge target medium 116 (in the sub-scanning direction indicated by arrow S in the drawing). In the main scanning direction indicated by arrow M), a number of nozzles 51 (liquid ejection ports) that eject ink toward the ejection medium 116 are two-dimensionally formed over a length corresponding to the width Wm of the ejection medium 116. It has an arrayed structure.

  The liquid discharge head 50 includes a plurality of liquid discharge elements 54 including a nozzle 51 for discharging liquid, a pressure chamber 52 communicating with the nozzle 51, a liquid supply port 53 for supplying liquid to the pressure chamber 52, and the like. They are arranged along two oblique directions that form a predetermined acute angle θ (0 degree <θ <90 degrees) with respect to the scanning direction M and the main scanning direction M. In FIG. 1, only a part of the liquid ejection elements 54 is illustrated for convenience of illustration.

  Specifically, the nozzles 51 are arranged at a constant pitch d in an oblique direction that forms a predetermined acute angle θ with respect to the main scanning direction M, so that d is aligned on a straight line along the main scanning direction M. It can be handled equivalently to those arranged at intervals of x cos θ.

  A vertical section taken along line 2-2 of FIG. 1 is shown in FIG.

  In FIG. 2, the liquid ejection head 50 includes a nozzle 51 that ejects liquid, a pressure chamber 52 that communicates with the nozzle 51 and is filled with liquid, a liquid supply port 53 that supplies liquid to the pressure chamber 52, and a liquid A common flow channel 55 communicating with the pressure chamber 52 via the supply port 53 and a piezoelectric element 58 as an actuator for changing the pressure in the pressure chamber 52 are configured.

  2 shows only one liquid ejection element 54 for convenience of illustration, the liquid ejection head 50 is actually a plurality of liquid ejection elements arranged in a two-dimensional manner as shown in FIG. An element 54 is used. Specifically, one liquid ejection element 54 includes one nozzle 51, one pressure chamber 52, one liquid supply port 53, and one piezoelectric element 58. That is, the liquid discharge head 50 actually includes a plurality of nozzles 51, a plurality of pressure chambers 52, a plurality of liquid supply ports 53, and a plurality of piezoelectric elements 58.

  The liquid discharge head 50 is configured by joining the nozzle plate 21 on which the nozzles 51 are formed to the pressure chamber plate 22 on which the pressure chambers 52 and the like are formed. That is, one surface of the nozzle plate 21 is a nozzle surface 21 a in which the nozzles 51 are two-dimensionally arranged as shown in FIG. 1, and the other surface of the nozzle plate 21 is joined to the pressure chamber plate 22. It becomes the joint surface 21b.

  In the pressure chamber plate 22, a pressure chamber 52, a liquid supply port 53, and a common flow channel 55 are formed.

  A vibration plate 23 is bonded to the surface of the pressure chamber plate 22 opposite to the bonding surface 21 b with the nozzle plate 21, and constitutes an upper surface plate of the pressure chamber 52. A piezoelectric element 58 is formed on the diaphragm 23.

  The pressure chamber plate 22 in the present invention refers to a material to be joined to the nozzle plate 21. The pressure chamber plate 22 shown in FIG. 2 is an example, and is not particularly limited in such a case. The pressure chamber plate 22 may be a structure in which a plurality of plates are stacked. Further, the common flow channel 55 is not formed in the pressure chamber plate 22, and on the opposite side to the arrangement side of the pressure chamber 52 (upper side of the piezoelectric element 58 in FIG. 2) with the diaphragm 23 and the piezoelectric element 58 interposed therebetween, The common channel 55 may be formed as a so-called back channel.

  The nozzle plate 21 has a nozzle 51 that passes through the nozzle plate 21 and communicates with the pressure chamber 52, and a recess 30 that is formed around the nozzle 51 and exposes the pressure chamber plate 22 through the nozzle plate 21.

  That is, when the liquid ejection head 50 is viewed from the nozzle plate 21 side, the inner surface 30a of the recess 30 of the nozzle plate 21 (that is, the exposed portion of the pressure chamber 51 plate) is the material of the pressure chamber plate 22 (for example, silicon The nozzle plate 21 made of a material different from the SUS (stainless steel) material (for example, polyimide) is not joined.

  Since there are various types of nozzle plates 21 in which such recesses 30 are formed, the following description will be divided into various examples.

[Example 1]
FIG. 3 is a perspective view of a main part of the first embodiment, showing a part of the nozzle plate 21 joined to the pressure chamber plate 22 as viewed from the nozzle surface 21a side. Further, one nozzle 51 on the nozzle plate 21 shown in FIG. 3 and a plurality of recesses 30 formed around the nozzle 51 are enlarged and shown in an enlarged plan view of a main part of FIG.

  As shown in FIG. 3, the nozzle plate 21 is formed with a plurality of nozzles 51 arranged two-dimensionally. Further, as shown in FIG. 4, a plurality of concave portions 30 are arranged at equal intervals on the circumference of a circle 301 as a closed curve surrounding each nozzle 51 with each nozzle 51 as the center.

  Specifically, the distance between the center 51 c of the nozzle 51 through which the axis of the nozzle 51 passes and the center 30 c of each recess 30 surrounding the nozzle 51 is the same for all the recesses 30 surrounding the nozzle 51. In addition, a plurality of recesses 30 are evenly arranged on the circumference of the circle 301. As a result, the stress is uniformly relieved around each nozzle 51 for each nozzle 51.

  3 and 4 show the case where the diameter of the pseudo hole (dummy hole) as the concave portion 30 having the circular opening is smaller than the diameter of the nozzle 51, the diameter of the pseudo hole is set to the nozzle 51. It may be larger than the diameter.

[Example 2]
FIG. 5 is an enlarged plan view of a main part of the second embodiment, showing one nozzle 51 on the nozzle plate 21 and a plurality of recesses 30 formed around the nozzle 51.

  In FIG. 5, eight concave portions 30 are arranged on the circumferences of circles 301 and 302 that are concentric for each nozzle 51 around the axis 51 c of the nozzle 51. These recesses 30 are arranged on each radiation centered on the axis 51 c of the nozzle 51. That is, the plurality of recesses 30 are arranged radially on the concentric circles 301 and 302. The plurality of concave portions 30 are formed so that the concave portions 30 on the concentric circles 301 and 302 are different from each other (that is, the concave portion 30 on the first concentric circle 301 and the concave portion 30 on the second concentric circle 302) are staggered. Staggered arrangement. In other words, the concave portion 30 on the first concentric circle 301 and the concave portion 30 on the second concentric circle 302 are arranged on different radiations.

  3, 4, and 5 exemplify the case where the opening shape of the nozzle 51 is circular, the opening shape of the nozzle 51 is not particularly limited to a circular shape. The opening shape of the nozzle 51 is, for example, a square (regular tetragon) shown in FIG. 6 (A), a regular hexagon shown in FIG. 6 (B), or a star-decagon shown in FIG. 6 (C). Also good. It may be another polygonal shape such as an equilateral triangle, or another circular shape such as an ellipse.

[Example 3]
FIG. 7 is a main part enlarged plan view of the third embodiment showing one nozzle 51 on the nozzle plate 21 and a plurality of recesses 30 formed around the nozzle 51.

  In FIG. 7, the nozzle 51 has a square opening shape. Four recesses 30 are arranged for one nozzle 51. These four recesses 30 are divided into bisectors (first symmetry axis 341 and second symmetry axis 342) of each square in the square which is the opening shape of the nozzle 51, and vertical bisectors of each side of the square. The lines (the third symmetry axis 343 and the fourth symmetry axis 344) are formed in a symmetrical pattern with respect to a total of four symmetry axes 341 to 344 as a symmetry axis set. That is, the symmetry axis of the shape of the nozzle 51 and the symmetry axis of the shape and the arrangement pattern of the recesses 30 coincide with each other. Here, the “pattern” of the recess 30 refers to a pattern formed by a collection of a plurality of recesses 30 surrounding one nozzle 51.

  In the present example, the four recesses 30 include a circle 301 centering on the axis 51 c of the nozzle 51, a third symmetry axis 343 and a fourth symmetry axis 344 (that is, two vertical sides of each square of the opening shape of the nozzle 51). It is arranged at the intersection with (isoline).

[Example 4]
FIG. 8 is an enlarged plan view of a main part of the fourth embodiment showing one nozzle 51 on the nozzle plate 21 and a plurality of recesses 30 formed around the nozzle 51.

  In FIG. 8, the nozzle 51 has a square opening shape. Four recesses 30 are arranged for one nozzle 51. These four recesses 30 are divided into bisectors (first symmetry axis 341 and second symmetry axis 342) of each square in the square which is the opening shape of the nozzle 51, and vertical bisectors of each side of the square. The lines (the third symmetry axis 343 and the fourth symmetry axis 344) are formed in a symmetrical pattern with respect to a total of four symmetry axes 341 to 344 as a symmetry axis set. That is, the symmetry axis of the shape of the nozzle 51 and the symmetry axis of the shape and the arrangement pattern of the recesses 30 coincide with each other. The above is the same as that of the third embodiment shown in FIG.

  In this example, the four recesses 30 include a circle 301 centered on the axis 51 c of the nozzle 51, a first symmetry axis 341, and a second symmetry axis 342 (that is, two inner corners of the square that is the sectional shape of the nozzle 51, etc.) It is arranged at the intersection with (divided line).

[Example 5]
FIG. 9 is a main part enlarged plan view of the fifth embodiment showing one nozzle 51 on the nozzle plate 21 and a plurality of recesses 30 formed around the nozzle 51.

  In the description of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment, as shown in FIGS. 3, 5, 6, and 7, the case where the concave portion 30 has a circular opening shape is taken as an example. Although shown, the opening shape of the recess 30 is not particularly limited to a circular shape.

  In FIG. 9, the recess 30 has a slit-shaped opening. The four recesses 30 include a circle 301 centered on the axis 51c of the nozzle 51, a third symmetry axis 343, and a fourth symmetry axis 344 (that is, a perpendicular bisector of each side of a square that is the sectional shape of the nozzle 51). Are arranged so as to face each side of the square which is the opening shape of the nozzle 51. The other points are the same as those of the third embodiment shown in FIG. 7, and the description of the contents already described is omitted here.

  In FIG. 9, the nozzle 51 has a square opening shape, and the concave portion 30 has a substantially rectangular opening shape as a slit. However, the present invention is particularly effective in such a case. It is not limited. For example, the nozzle 51 may have a circular opening shape, and the concave portion 30 may be a slit having an arc-shaped opening shape along a circle 301 centering on the axis 51 c of the nozzle 51.

[Example 6]
FIG. 10 is an enlarged plan view of a main part of the sixth embodiment showing one nozzle 51 on the nozzle plate 21 and a plurality of recesses 30 formed around the nozzle 51.

  In FIG. 10, the nozzle 51 has a star-shaped decagonal opening shape. In detail, in this star-shaped decagon, five of the ten interior angles are acute angles (<90 degrees), and the other five interior angles are obtuse angles (> 90 degrees). Here, the five acute angles are the same angle, and the five obtuse angles are the same angle. Moreover, the length of 10 sides is equal.

  Five recesses 30 are arranged for one nozzle 51. These five concave portions 30 have a total of five symmetry axes 351 with the bisectors 351, 352, 353, 354, and 355 of the inner angles of the star-decagon that is the opening shape of the nozzle 51 as a symmetry axis set. It is formed in a symmetrical pattern with respect to ˜355.

  The five recesses 30 are the intersections of the circle 301 centered on the axis 51c of the nozzle 51 and the bisectors 351 to 355 of the inner angles of the star-shaped decagon, and are formed of obtuse angles (<90 degrees). It is arranged so as to face the V shape formed by the inner corners.

  Note that the recess 30 shown in FIG. 10 has a circular opening shape, but the opening shape of the recess 30 is not particularly limited to a circular shape. For example, it may be a polygon or a slit.

[Example 7]
FIG. 11 is an enlarged plan view of a main part of the seventh embodiment, showing one nozzle 51 on the nozzle plate 21 and a plurality of recesses 30 formed around the nozzle 51. The surrounding area is shown.

  In FIG. 11, the nozzle 51 has a regular hexagonal opening shape. Six recesses 30 are arranged for one nozzle 51. These six concave portions 30 are divided into bisectors 361, 362, and 363 at the respective internal angles of the regular hexagon that is the opening shape of the nozzle 51, and vertical bisectors 364, 365, and 363 at each side of the regular hexagon. Are formed in a symmetrical pattern with respect to a total of six symmetry axes 361 to 366 as a symmetry axis set.

  The six recesses 30 are arranged at the intersections of a circle 301 centered on the axis 51 c of the nozzle 51 and a perpendicular bisector of each side of the regular hexagon that is the opening shape of the nozzle 51.

  Note that the recess 30 shown in FIG. 11 has an approximately crescent-shaped opening shape, but the opening shape of the recess 30 is not particularly limited to such a shape.

[Example 8]
FIG. 12 is a main part enlarged plan view of the eighth embodiment showing the nozzle groups 511 and 512 on the nozzle plate 21 and a plurality of recesses 30 formed around the nozzle groups 511 and 512.

  In FIG. 12, each nozzle group 511, 512 is configured by N (seven in FIG. 12) nozzles 51. For example, in the two-dimensional array of nozzles 51 of the liquid ejection head 50 shown in FIG. 1, one nozzle group 510 is constituted by N consecutive nozzles 51 arranged along the main scanning direction M.

  L (22 in FIG. 12) concave portions 30 are arranged on closed curves 311 and 312 surrounding the nozzle groups 511 and 512, respectively.

  That is, a plurality (22 in FIG. 12) of recesses 30 are arranged on each of the closed curves 311 and 312 surrounding the plurality of (in FIG. 12, 14 in total) nozzles 51 for each of the nozzle groups 511 and 512.

  FIG. 12 shows a case where one nozzle group 511 is surrounded by a single closed curve 311 and the recesses 30 are arranged in series on the closed curve 311. However, the present invention is not particularly limited to such a case. The concave portions 30 may be arranged on a plurality of closed curves, or the concave portions 30 may be arranged in a staggered arrangement.

[Example 9]
FIG. 13 is an enlarged plan view of a main part of the ninth embodiment showing nozzle groups 511 and 512 on the nozzle plate 21 and a plurality of recesses 30 formed around the nozzle groups 511 and 512.

  In FIG. 13, each nozzle group 511, 512 is configured by N (seven in FIG. 12) nozzles 51. For example, in the two-dimensional array of nozzles 51 of the liquid ejection head 50 shown in FIG. 1, one nozzle group 510 is constituted by N consecutive nozzles 51 arranged along the main scanning direction M.

  Further, one recess 30 is formed so as to draw a closed curve surrounding one nozzle group (511 or 512).

[Example 10]
FIG. 14 is a plan view illustrating the entire nozzle surface 21a of the nozzle plate 21 according to the tenth embodiment. FIGS. 15A, 15B, and 15C are enlarged plan views of main parts, showing an enlarged portion indicated by reference numeral 15 in FIG.

  In this example, as shown in FIG. 14, the entire nozzle surface 21a of the nozzle plate 21 is divided into a plurality of divided areas 21e. Specifically, a row of pseudo through holes 41 (dummy holes) arranged in series as shown in FIG. 15 (A) formed in the nozzle surface 21a, and pseudo through holes arranged in a staggered arrangement as shown in FIG. 15 (B). The entire surface of the nozzle surface 21a is divided into a plurality of divided areas 21e by a row of 41 (dummy holes) or a groove 42 shown in FIG.

  The pseudo through hole 41 in FIGS. 15A and 15B and the groove 42 in FIG. 15C penetrate the nozzle plate 21 and expose the pressure chamber plate 22.

  In addition, although illustration was abbreviate | omitted in each division area 21e, the nozzle 51 and recessed part 30 (specifically FIG.4, FIG.5, FIG.7, FIG.8) demonstrated in either of Examples 1-9. 9, 10, 11, 12, and 13, the nozzle 51 and the concave portion 30) shown in any one of the drawings are formed.

  As described above, although various embodiments have been described separately, in any of the embodiments, the stress generated around the nozzle 51 is relieved by the concave portion 30 in the usage environment of the liquid discharge head 50, and the shape of the nozzle 51 is deformed. It is possible to obtain a desired shape deformation exclusively associated with a pressure change in the liquid discharge head 50.

  Such an effect is particularly effective when the opening cross section of the nozzle 51 is not a circular shape but a polygonal shape such as a regular polygonal shape or a star shape, or when the nozzle 51 has a tapered shape.

  FIG. 16A is an enlarged cross-sectional view showing an example of a nozzle 51 having a tapered shape and its periphery.

  In FIG. 16A, the nozzle 51 has an inclination in which the opening cross-sectional area gradually decreases from the joining surface 21b of the nozzle plate 21 to the pressure chamber plate 22 to the nozzle surface 21a.

  Due to the presence of the concave portion 30 arranged around the nozzle 51, the opening edge 51e having a small rigidity is not affected by the stress around the opening edge 51e and is released from the stress.

  FIG. 16B is an enlarged cross-sectional view showing another example of the nozzle 51 having a tapered shape and its periphery.

  In FIG. 16B, the nozzle 51 has a nozzle surface 21a from a joint surface 21b between a straight portion 51s having a substantially identical opening cross-sectional area in the vicinity of the nozzle surface 21a of the nozzle plate 21 and the pressure chamber plate 22 of the nozzle plate 21. And an inclined portion 51t whose opening cross-sectional area gradually decreases.

[Production method]
Next, an example of a method for manufacturing the liquid discharge head 50 will be described with reference to the process chart of FIG.

  First, as shown in FIG. 17A, a plate material in which the nozzle 51 and the recess 30 are not yet formed is prepared as the nozzle plate 21.

  Examples of the material of the nozzle plate 21 include polyimide.

  Next, as shown in FIG. 17B, the nozzle 51 and the recess 30 are formed in the nozzle plate 21.

  Examples of the method for forming the recess 30 include general nozzle forming techniques such as excimer laser processing, electroforming processing, press processing, dry etching processing, wet etching processing, and electric discharge processing.

  The recess 30 is simultaneously formed by the same formation method as the nozzle 51.

  For example, the diameter of the nozzle 51 is 10 to 20 μm, and the diameter of the pseudo hole (dummy hole) as the recess 30 is 20 to 50 μm.

  In addition, it is more preferable that the concave portion 30 has the same cross-sectional shape as the nozzle 51 in the cross section (vertical cross section) along the thickness direction of the nozzle plate 21 and is formed simultaneously with the nozzle 51. For example, as shown in FIG. 17B, if the nozzle 51 is tapered, the recess 30 is simultaneously formed in a tapered shape. On the other hand, if the nozzle is a straight shape, the concave portion is simultaneously formed in a straight shape.

  Next, the nozzle plate 21 is joined to a separately formed pressure chamber plate 22. Specifically, a structure 24 including a pressure chamber 52, a liquid supply port 53, a common flow channel 55, and a piezoelectric element 58 shown in FIG. The nozzle plate 21 is joined to the pressure chamber plate 22.

  Examples of the material of the pressure chamber plate 22 include silicon and SUS (stainless steel) material.

  The nozzle plate 21 and the pressure chamber plate 22 are joined using an adhesive, diffusion bonding, eutectic bonding, metal welding, anodic bonding, or the like.

  In addition, when the groove | channel is formed in the nozzle plate 21 and it cannot handle as integral, the recessed part 30 is formed in the state which affixed the support substrate to the discharge surface side of the nozzle plate 21 previously, and it joined to the pressure chamber board 22 Later, the support substrate is separated. Alternatively, the groove-shaped recess 30 may be formed after the pressure chamber plate 22 is joined to the nozzle plate 21.

[Image forming apparatus]
FIG. 18 is an overall configuration diagram of an example of the image forming apparatus 110 including the liquid ejection head 50 according to the present invention.

  In FIG. 18, the image forming apparatus 110 supplies a liquid discharge unit 112 having a plurality of liquid discharge heads 112 </ b> K, 112 </ b> C, 112 </ b> M, 112 </ b> Y provided for each color of ink and the liquid discharge heads 112 </ b> K, 112 </ b> C, 112 </ b> M, 112 </ b> Y. An ink storage / loading unit 114 for storing ink to be stored, a paper feeding unit 118 for supplying a medium to be ejected 116 such as paper, a decurling unit 120 for removing the curl of the medium to be ejected 116, and a liquid ejecting unit 112. The belt conveyance unit 122 that conveys the medium to be ejected 116 while maintaining the flatness of the medium to be ejected 116, and the ejection result by the liquid ejection unit 112 (droplet landing state) And a paper discharge unit 126 that discharges the printed target medium to the outside.

  As the liquid discharge heads 112K, 112C, 112M, and 112Y in FIG. 18, the liquid discharge head 50 shown in FIGS. 1 and 2 is used. From these liquid discharge heads 112K, 112C, 112M, and 112Y, a medium to be discharged is used. By ejecting a liquid (ink) containing a colorant (also referred to as a “coloring material”) toward 116, an image is formed on the ejection target medium 116.

  In FIG. 18, as an example of the paper feeding unit 118, a paper that feeds roll paper (continuous paper) is shown, but a paper that feeds cut paper that has been cut in advance may be used. In the case of an apparatus configuration that uses roll paper, a cutter 128 is provided. Incidentally, the discharge medium 116 delivered from the paper supply unit 118 generally retains curl and curls. In order to remove this curl, heat is applied to the medium 116 to be ejected by the heating drum 130 in the direction opposite to the curl direction in the decurling unit 120. After the decurling process, the cut discharged medium 116 is sent to the belt conveyance unit 122.

  The belt conveyance unit 122 has a structure in which an endless belt 133 is wound between rollers 131 and 132, and at least portions facing the nozzle surface of the liquid discharge unit 112 and the sensor surface of the discharge detection unit 124 are flat ( Flat surface). The belt 133 has a width that is greater than the width of the medium 116 to be ejected, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 18, an adsorption chamber 134 is provided at a position facing the nozzle surface of the liquid discharge unit 112 and the sensor surface of the discharge detection unit 124 inside the belt 133 spanned between the rollers 131 and 132. The suction chamber 134 is sucked by the fan 135 to be a negative pressure, and the discharged medium 116 on the belt is sucked and held. The power of a motor (not shown) is transmitted to at least one of the rollers 131 and 132 around which the belt 133 is wound, so that the belt 133 is driven clockwise in FIG. 18 and held on the belt 133. The discharged medium 16 is conveyed from left to right in FIG. Note that, when a borderless print or the like is formed, the ink also adheres to the belt 133. Therefore, the belt cleaning unit 136 is provided at a predetermined position outside the belt 133 (an appropriate position other than the print region). A heating fan 140 is provided on the upstream side of the liquid ejection unit 112 on the paper conveyance path formed by the belt conveyance unit 122. The heating fan 140 blows heated air onto the medium to be ejected 116 before printing to heat the medium to be ejected 116. Heating the ejection medium 116 immediately before printing makes it easier for the ink to dry after landing.

  FIG. 19 is a main part plan view showing the liquid ejection part 112 of the image forming apparatus 110 and its peripheral part.

  As shown in FIG. 19, the liquid ejection unit 112 has a so-called full line in which a full-line head having a length corresponding to the maximum paper width is arranged in a direction (main scanning direction) perpendicular to the medium transport direction (sub-scanning direction). It is a line-type head. Specifically, each of the liquid discharge heads 112K, 112C, 112M, and 112Y has a plurality of nozzles (liquid discharge ports) over a length that exceeds at least one side of the maximum-size discharge target medium 116 that the image forming apparatus 110 is symmetrical to. It consists of an arrayed full line type head.

  Corresponding to each color ink in the order of black (K), cyan (C), magenta (M), yellow (Y) from the upstream side (left side in FIG. 19) along the transport direction (medium transport direction) of the medium 116 to be ejected. The liquid discharge heads 112K, 112C, 112M, and 112Y are disposed. A color image can be formed on the ejection medium 116 by ejecting ink containing a color material from each of the liquid ejection heads 112K, 112C, 112M, and 112Y while conveying the ejection medium 116.

  As described above, according to the liquid discharge unit 112 in which the full line head covering the entire paper width is provided for each ink color, the target medium 116 and the liquid discharge unit 112 are relatively moved in the medium transport direction (sub-scanning direction). It is possible to record an image on the entire surface of the medium 116 to be ejected only by performing the operation of moving the image to once (that is, in one sub-scan). Thus, high-speed printing is possible and productivity can be improved as compared with a shuttle type head that reciprocates in a direction (main scanning direction) orthogonal to the medium conveyance direction.

  The main scanning direction and the sub scanning direction are used in the following meaning. That is, when driving the nozzles with a full line head having a nozzle row corresponding to the entire width of the medium to be ejected, (1) all the nozzles are driven simultaneously or (2) the nozzles are sequentially driven from one side to the other. Or (3) the nozzles are divided into blocks, and one of the nozzles is driven sequentially from one side to the other for each block, and the width direction of the target medium (the target medium) The driving of the nozzle that prints one line (a line formed by a single line of dots or a line composed of a plurality of lines) in the direction orthogonal to the transport direction is defined as main scanning. A direction indicated by one line (longitudinal direction of the belt-like region) recorded by the main scanning is called a main scanning direction.

  On the other hand, by relatively moving the above-described full line head and the medium to be ejected, printing of one line (a line formed by one line of dots or a line composed of a plurality of lines) formed repeatedly by the above-described main scanning is repeatedly performed. This is defined as sub-scanning. A direction in which sub-scanning is performed is referred to as a sub-scanning direction. Eventually, the transport direction of the medium to be ejected is the sub-scanning direction, and the direction orthogonal to it is the main scanning direction.

  In this embodiment, the configuration of KCMY standard colors (four colors) is illustrated, but the number of ink colors and color combinations are not limited to the examples shown in this embodiment, and light ink is used as necessary. Dark ink may be added. For example, it is possible to add an ink discharge head that discharges light-colored ink such as light cyan and light magenta.

  As shown in FIG. 18, the ink storage / loading unit 114 includes ink tanks that store inks of colors corresponding to the liquid ejection heads 112K, 112C, 112M, and 112Y, and the ink tanks are not illustrated. The liquid discharge heads 112K, 12C, 112M, and 112Y communicate with each other via a pipe line.

  The ejection detection unit 124 includes an image sensor (line sensor or the like) for imaging the ejection result of the liquid ejection unit 112, and functions as a unit that checks nozzle clogging and other ejection defects from an image read by the image sensor. To do.

  A post-drying unit 142 is provided following the discharge detection unit 124. The post-drying unit 142 is means for drying the printed image surface, and for example, a heating fan is used. A heating / pressurizing unit 144 is provided following the post-drying unit 142. The heating / pressurizing unit 144 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 145 having a surface with a predetermined uneven shape while heating the image surface, thereby forming the uneven shape on the image surface. Transcript.

  The printed matter generated in this manner is outputted from the paper output unit 126. The image forming apparatus 110 is provided with sorting means (not shown) for switching the paper discharge path in order to select the printed material of the main image and the printed material of the test print and send them to the respective discharge units 126A and 126B. ing. When the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 148. The cutter 148 is provided immediately before the paper discharge unit 126, and cuts the main image and the test print unit when a test print is performed on an image margin. Although not shown, the paper output unit 126A for the target prints is provided with a sorter for collecting prints according to print orders.

  The present invention is not limited to the examples described in the present specification and the examples illustrated in the drawings, and various design changes and improvements may be made without departing from the spirit of the present invention.

  Although the case where the actuator of the liquid discharge head 50 is configured by a piezoelectric element has been described as an example, the actuator in the present invention is not limited to a piezoelectric element. For example, the present invention can also be applied when an actuator is constituted by an electrothermal element (heater).

  Although the case where the liquid discharge head 50 discharges ink as a liquid has been described as an example, the liquid in the present invention is not limited to ink. For example, the present invention can be applied to the case where a liquid containing a conductive material for wiring is discharged.

Plane perspective view showing the overall configuration of an example of the liquid discharge head 50 1 is a vertical sectional view taken along line BB in FIG. 1 is a perspective view showing a main part of a liquid discharge head according to a first embodiment. The principal part enlarged plan view of the liquid discharge head of 1st Example The principal part enlarged plan view of the liquid discharge head of 2nd Example Plan view showing an example of the nozzle opening shape The principal part enlarged plan view of the liquid discharge head of 3rd Example The principal part enlarged plan view of the liquid discharge head of 4th Example The principal part enlarged plan view of the liquid discharge head of 5th Example The principal part enlarged plan view of the liquid discharge head of 6th Example The principal part enlarged plan view of the liquid discharge head of 7th Example The principal part enlarged plan view of the liquid discharge head of 8th Example The principal part enlarged plan view of the liquid discharge head of 9th Example The top view which shows the nozzle surface of the liquid discharge head of 10th Example The principal part enlarged plan view which expands and shows a part of FIG. Vertical sectional view showing an example of the vertical sectional shape of the nozzle Process diagram used to explain the manufacturing process of the liquid discharge head Overall configuration diagram showing an example of the overall configuration of the image forming apparatus Main part plan view showing a liquid discharge part and its periphery of an image forming apparatus

Explanation of symbols

  21 ... Nozzle plate, 21a ... Nozzle surface, 21b ... Joint surface of nozzle plate with pressure chamber plate, 21e ... Divided area, 22 ... Pressure chamber plate, 23 ... Vibration plate, 30 ... Recess, 30a ... Back surface of recess, 30c ... Center of the recess, 41 ... Pseudo hole array at the boundary of the divided area, 42 ... Groove at the boundary of the divided area, 50, 112K, 112C, 112M, 112Y ... Liquid ejection head, 116 ... Medium to be ejected, 51 ... Nozzle, 51c: Nozzle center (axis), 51e: Nozzle edge, 52 ... Pressure chamber, 53 ... Liquid supply port, 54 ... Liquid ejection element, 55 ... Common flow path, 58 ... Piezoelectric element, 110 ... Image forming apparatus, 301 , 302, 311, 312 ... closed curve, 341 to 344, 351 to 355, 361 to 366 ... symmetry axis, 511, 512 ... nozzle group

Claims (15)

A pressure chamber plate in which a pressure chamber filled with liquid is formed;
A nozzle plate joined to the pressure chamber plate;
With
The nozzle plate is
A plurality of nozzles penetrating the nozzle plate and communicating with the pressure chamber;
A recess formed around the nozzle and penetrating the nozzle plate to expose the pressure chamber plate;
A liquid discharge head comprising:   2. The liquid ejection head according to claim 1, wherein a plurality of the concave portions are arranged on each closed curve surrounding the plurality of nozzles for each nozzle.   A plurality of the concave portions are arranged on a plurality of concentric closed curves surrounding the plurality of nozzles for each nozzle, and the concave portions on different concentric closed curves are staggered so as to be staggered. The liquid discharge head according to claim 2.   2. The liquid ejection head according to claim 1, wherein a symmetry axis of the shape of the concave portion and an arrangement pattern coincides with a symmetry axis of the opening shape of the nozzle. The opening shape of the nozzle is a regular polygon,
The plurality of recesses are symmetric with respect to the bisector of each inner angle of the regular polygon that is the opening shape of the nozzle for each nozzle, and the vertical bisector of each side of the regular polygon The liquid discharge head according to claim 4, wherein the liquid discharge head is formed in a symmetrical pattern. The nozzle opening shape is a star polygon,
5. The plurality of concave portions are formed in a symmetrical pattern with respect to each bisector of each inner angle of a star polygon that is an opening shape of the nozzle, for each of the nozzles. The liquid discharge head described.   2. The liquid ejection head according to claim 1, wherein a plurality of the recesses are arranged on each closed curve surrounding the plurality of nozzles for each nozzle group. 3.   The liquid ejection head according to claim 1, wherein the concave portion is formed so as to draw a closed curve surrounding the nozzle.   The liquid ejection head according to claim 1, wherein the nozzle plate is formed with a through-hole row or a groove that divides the entire surface of the nozzle plate into a plurality of divided areas. .   The liquid discharge head according to claim 1, wherein the nozzle has a tapered shape. In a method for manufacturing a liquid ejection head, comprising: a pressure chamber plate in which a pressure chamber filled with liquid is formed; and a nozzle plate joined to the pressure chamber plate.
Forming a plurality of nozzles penetrating the nozzle plate and communicating with the pressure chamber in the nozzle plate, and a recess disposed around the nozzle and exposing the pressure chamber plate through the nozzle plate. A method of manufacturing a liquid discharge head, comprising:   The method of manufacturing a liquid ejection head according to claim 11, wherein the recess is formed by the same formation method as the formation method of the nozzle.   The method of manufacturing a liquid discharge head according to claim 12, wherein the recess is formed in the same cross-sectional shape as the nozzle in a cross section in the thickness direction of the nozzle plate and simultaneously with the nozzle.   A liquid discharge apparatus comprising the liquid discharge head according to claim 1.   An image forming apparatus comprising the liquid discharge head according to claim 1.

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