JP6252156B2 - Inkjet head - Google Patents

Description

  The present invention relates to an inkjet head, and more specifically, it is possible to suppress the flow of adhesive into the nozzle even when the nozzle density is high, and to suppress the occurrence of a gap due to the adhesive surface of the nozzle plate floating from the head chip. The present invention relates to an inkjet head.

  An inkjet head in which a nozzle plate having nozzles for discharging liquid is bonded to the end face of the head chip with an adhesive is used when the nozzle plate and the head chip are bonded to each other as the nozzles become denser and multi-rowed. In other words, the adhesive flows into the nozzle and causes nozzle clogging, or the gap between the nozzle plate and the head chip does not come into close contact.

  The problem of nozzle clogging has an effect that the density of the pressure chambers provided in the head chip increases as the nozzle density increases, and the opening width of the pressure chambers becomes narrower. In addition, as the number of pressure chambers increases, the size of the head chip increases, making it difficult to uniformly apply the adhesive to the whole, and a portion where the amount of application increases partially tends to occur. It is thought that this also has an effect.

  On the other hand, the problem that the gap is generated is mainly due to the uneven end face of the head chip to which the nozzle plate is bonded. This unevenness is generated by forming a partial protrusion on the end face of the head chip. Such partial protrusions may also occur due to the attachment of minute foreign matters such as dust, but in particular, the surface of the head chip is often coated with a parylene film for protecting the electrode member from ink. It can be seen. In general, since the parylene film is coated over the surface of the head chip including the surface of the electrode member, the parylene film is also formed on the end surface bonded to the nozzle plate. Such a parylene film is known to sometimes cause 1 to 10 μm protruding foreign matter due to abnormal growth of parylene, and when this protruding foreign matter occurs on the end surface bonded to the nozzle plate, The nozzle plate is lifted from the surface of the head chip, and a gap is generated between the nozzle plate and the head chip.

  The gap generated between the nozzle plate and the head chip can be eliminated by adding an adhesive between the end of the nozzle plate and the head chip to fill the gap, and this is not a problem. However, if there are gaps between the rows of multiple nozzle rows, even if the adhesive is poured from the end of the nozzle plate, it will flow into the pressure chambers and nozzles when crossing the nozzle rows. It is extremely difficult to make the adhesive reach the gap between them.

  FIG. 15 shows a state where an ink jet head in which a convex portion is generated on the end face of the head chip between the nozzle rows is viewed from the surface of the nozzle plate. In the figure, 100 is a pressure chamber, 200 is a nozzle, and 300 is a convex portion. Thus, when the convex part 300 has generate | occur | produced in the end surface of a head chip, the clearance gap 400 will be formed in the circumference | surroundings of the convex part 300 between a nozzle plate and a head chip. The adhesive cannot flow into the gap 400 due to the capillary force, so that the adhesive is insufficient and remains as a gap.

  If such a gap 400 reaches both the adjacent pressure chambers 300 and 300 as shown in the drawing, the pressure chambers 300 and 300 may leak (communicate) with each other. When such a leak occurs, the ink in the pressure chamber 300 cannot be stably discharged, which causes a discharge failure. The higher the density of the nozzle 200, the closer the gap between the adjacent pressure chambers 300, 300, so that the problem of leakage due to such a gap 400 becomes more prominent.

  Conventionally, a technique has been proposed in which an adhesive escape groove is formed on the adhesive surface of the nozzle plate so as to surround the nozzle, thereby preventing excess adhesive from entering the nozzle (Patent Document 1). ).

JP 2002-307687 A

  As described in Patent Document 1, by forming an adhesive escape groove in the nozzle plate, it is possible to suppress the flow of excess adhesive into the nozzle. However, as a result of investigation by the present inventor, it has been found that even if the adhesive escape groove is formed so as to surround the nozzle, it cannot be fully accommodated as the density of the nozzle increases.

  That is, as the nozzle density increases, the pressure chambers increase in density, and the interval between nozzles adjacent in the nozzle row direction becomes extremely narrow. For this reason, it is extremely difficult to form a groove between nozzles adjacent in the nozzle row direction.

  Moreover, even if the adhesive escape groove is simply formed so as to surround the nozzle, the problem that the gap generated by the rising of the nozzle plate leaks the pressure chambers cannot be solved.

  Therefore, the present invention can suppress the flow of the adhesive into the nozzle even when the nozzle density is high, and the convex portion formed on the end surface of the head chip to which the nozzle plate is bonded causes a gap between the pressure chamber rows. It is an object of the present invention to provide an ink jet head that can suppress the problem of occurrence of pressure and leakage between pressure chambers.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

1. A head chip in which a plurality of rows of pressure chambers in which a plurality of pressure chambers are arranged are arranged side by side, and a nozzle plate bonded to an end surface of the head chip on which an opening on the outlet side of the pressure chamber is disposed by an adhesive. In an inkjet head having
The nozzle plate has a first groove formed along the row of pressure chambers at a portion corresponding to the space between the rows of pressure chambers on the bonding surface with the head chip.
The depth value of the first groove is equal to or greater than the roughness value of the end face of the head chip to which the nozzle plate is bonded ;
The inkjet head according to claim 1, wherein the first groove has a shortest distance of 50 μm or more from the edge of the first groove to the edge of the opening on the outlet side of the pressure chamber .

2. Said first groove, said 1 Symbol placement inkjet head, characterized in that it is divided into a plurality of column direction of the pressure chamber.

  3. 2. The inkjet head according to claim 1, wherein two or more of the first grooves are provided along portions of the pressure chambers in portions corresponding to the rows of the pressure chambers.

4). A head chip in which a plurality of rows of pressure chambers in which a plurality of pressure chambers are arranged are arranged side by side, and a nozzle plate bonded to an end surface of the head chip on which an opening on the outlet side of the pressure chamber is disposed by an adhesive. In an inkjet head having
The nozzle plate has a first groove formed along the row of pressure chambers at a portion corresponding to the space between the rows of pressure chambers on the bonding surface with the head chip.
The depth value of the first groove is equal to or greater than the roughness value of the end face of the head chip to which the nozzle plate is bonded;
2. The inkjet head according to claim 1, wherein two or more of the first grooves extend along the rows of the pressure chambers at portions corresponding to the rows of the pressure chambers .

5. 3. The above 3 or 4, wherein B> D−C, where B is the groove width of the first groove, C is the depth of the first groove, and D is the thickness of the nozzle plate. Inkjet head.

6). 6. The ink jet head according to 3, 4, or 5 , further comprising a connecting groove for connecting the adjacent first grooves.

  7). The inkjet head according to any one of 1 to 6, wherein the first groove communicates with an outside of the nozzle plate at an end portion of the nozzle plate.

  8). The inkjet head according to any one of 1 to 7, wherein the first groove has a side wall surface formed in a tapered shape.

9. A head chip in which a plurality of rows of pressure chambers in which a plurality of pressure chambers are arranged are arranged side by side, and a nozzle plate bonded to an end surface of the head chip on which an opening on the outlet side of the pressure chamber is disposed by an adhesive. In an inkjet head having
The nozzle plate has a first groove formed along the row of pressure chambers at a portion corresponding to the space between the rows of pressure chambers on the bonding surface with the head chip.
The depth value of the first groove is equal to or greater than the roughness value of the end face of the head chip to which the nozzle plate is bonded;
The ink jet head according to claim 1, wherein the first groove has a side wall surface formed in a tapered shape .

10. 10. The inkjet head according to any one of 1 to 9 , wherein particles having a particle diameter of 1 μm to 3 μm are mixed in the adhesive.

11. 11. The inkjet head according to any one of 1 to 10 , wherein the head chip has a parylene film coated on the end face of the head chip to which the nozzle plate is bonded.
12 The inkjet head according to any one of 1 to 11 , wherein the nozzle plate is made of resin.

  According to the present invention, it is possible to suppress the flow of the adhesive into the nozzle even when the nozzle becomes high density, and the gaps between the pressure chamber rows are formed by the convex portions formed on the end surface of the head chip to which the nozzle plate is bonded. It is possible to provide an ink jet head capable of suppressing the problem that the pressure chambers leak due to the occurrence of pressure.

1 is a perspective view showing a first embodiment of an ink jet head according to the present invention, developed left and right on an adhesive surface between a nozzle plate and a head chip. End view showing a cut end face when the ink jet head shown in FIG. 1 is cut along line (ii)-(ii) Partial rear view of nozzle plate Partial rear view of nozzle plate explaining leakage between groove and channel Rear view of nozzle plate Partial sectional view of nozzle plate (A)-(c) is a figure explaining the cross-sectional shape of a groove | channel, respectively. Partial end view of inkjet head The perspective view which shows 2nd Embodiment of the inkjet head which concerns on this invention, and expand | deploys right and left by the adhesive surface of a nozzle plate and a head chip. End view showing a cut end face when the ink jet head shown in FIG. 9 is cut along line (x)-(x) End view showing the same cut end surface as FIG. Partial rear view of nozzle plate Rear view of nozzle plate Rear view of nozzle plate with 6 nozzle rows The figure explaining the state which the leak generate | occur | produced between the pressure chambers adjacent by the convex part

  Hereinafter, embodiments of the present invention will be described in detail.

(First embodiment)
FIG. 1 shows a first embodiment of an ink jet head according to the present invention, and is a perspective view showing a left and right developed by an adhesive surface between a nozzle plate and a head chip. FIG. 2 shows the ink jet head shown in FIG. ii) End view showing a cut end surface when cut along line ii), FIG. 3 and FIG. 4 are partial rear views of the nozzle plate, and FIG. 5 is a rear view of the nozzle plate showing another embodiment of the groove. FIG. 6 is a partial sectional view of the nozzle plate. In FIGS. 1 and 2, the adhesive is not shown.

  In the figure, 1 is a head chip and 2 is a nozzle plate.

  The head chip 1 has a hexahedral shape, and a plurality of channels 11 which are pressure chambers are arranged in parallel. A partition between adjacent channels 11 and 11 includes a piezoelectric element such as PZT at least partially, and serves as a driving wall 12 that functions as a pressure applying unit. One drive wall 12 is shared by the adjacent channels 11 and 11. The channels 11 and the drive walls 12 are arranged in parallel so as to constitute one channel row. In the head chip 1, the channel rows are arranged in two rows (first row and second row) in the vertical direction in the figure.

  As shown in FIG. 3, the depth E of each channel 11 of the head chip 1 is 150 μm to 450 μm, and the shortest distance F between the first and second channel columns is 400 μm to 1500 μm. It is said that.

  Each channel 11 opens to the end face 1a of the head chip 1 to which the nozzle plate 2 is bonded, and forms an opening 11a on the outlet side. The other end opens to the end face of the head chip 1 opposite to the end face 1a to form an inlet side opening (not shown). An ink manifold (not shown) is provided on the end surface side opposite to the end surface 1 a of the head chip 1, and ink is supplied in common to the opening portion on the inlet side of each channel 11.

  Drive electrodes (not shown) are formed on the surface of the drive wall 12 facing the channel 11. When a drive signal of a predetermined voltage is applied to a pair of drive electrodes sandwiching the drive wall 12 via a wiring on a wiring board (not shown) provided on the end face opposite to the end face 1a of the head chip 1, the drive wall 12 is sheared so as to expand or contract the volume of the channel 11, and operates to apply pressure for ejection to the ink in the channel 11.

  Here, the head chip 1 is shown having a parylene film 3 coated on the surface in order to protect the drive electrode in the channel 11 from ink. The parylene film 3 is a resin film made of paraxylylene and its derivatives, and is formed by a vapor phase synthesis method (Chemical Vapor Deposition: CVD method) using a solid diparaxylylene dimer or its derivative as an evaporation source. That is, paraxylylene radicals generated by vaporization and thermal decomposition of diparaxylylene dimer are adsorbed on the surface of the head chip 1 and undergo a polymerization reaction to form a film. There are various parylene films as the parylene film, and various parylene films or a multi-layered parylene film in which a plurality of these various parylene films are laminated can be applied depending on required performance and the like. The thickness of the parylene film 3 is generally 1 μm to 10 μm, and is coated on the surface of the head chip 1 before the nozzle plate 2 is bonded.

  In the nozzle plate 2, nozzles 21 are formed so as to correspond to the respective channels 11 of the head chip 1. That is, the nozzle plate 2 also has two nozzle rows. The nozzle plate 2 is bonded to the end surface 1a of the head chip 1 with an adhesive. In this embodiment, since the parylene film 3 is coated on the head chip 1, the end surface 1a of the head chip 1 to which the nozzle plate 2 is bonded is the parylene film 3 formed on the end surface 1a. Refers to the surface.

  The thickness D (see FIG. 6) of the nozzle plate 2 is generally 20 μm to 300 μm.

  The bonding surface 2a with the head chip 1 which is the back surface of the nozzle plate 2 has a portion corresponding to a position between two channel rows (first row and second row) arranged on the end surface 1a of the head chip 1 as 1 A groove (first groove) 22 is formed.

  The groove 22 can function as a so-called glue guard that receives an excess of the adhesive applied between the head chip 1 and the nozzle plate 2. The groove 22 is formed to extend linearly along the channel row direction (left-right direction in FIG. 3) with a predetermined width and depth so as not to overlap the channel 11 of each channel row.

  The depth value C of the groove 22 of the nozzle plate 2 (see FIG. 6) is equal to or greater than the value of the roughness Yp of the end face 1a of the head chip 1 to which the nozzle plate 2 is bonded. Here, the value of the roughness Yp of the end face 1a is a three-dimensional measurement of the surface roughness of the entire end face 1a excluding the opening 11a of the channel 11 of the head chip 1 (the height of the peak from the valley). It is a value obtained by measuring the height from the average height of the peak to the highest peak. For the measurement, for example, a shape measurement laser microscope (Keyence: VK-X100) can be used.

  When the convex part 3a has arisen in the end surface 1a of the head chip 1 which is an adhesive surface with this nozzle plate 2, the value of the roughness Yp of the end surface 1a will become large. When such a convex portion 3a is generated between two channel rows (first row and second row) and the nozzle plate 2 is partially lifted from the head chip 1 to form a gap, the end portion of the nozzle plate 2 Therefore, it is difficult to fill the gap even if the adhesive is poured, and conventionally, the gap is likely to remain. However, according to the present invention, since the depth value C of the groove 22 arranged in the region between the two channel rows is equal to or greater than the roughness Yp of the end face 1a, as shown in FIG. The convex portion 3 a generated at this portion can be accommodated in the groove 22. Thereby, the nozzle plate 2 is not partially lifted by the convex portion 3a, and the generation of a gap due to the rising of the nozzle plate 2 can be suppressed.

  Usually, since the value of the roughness Yp of the end face 1a of the head chip 1 when the parylene film 3 is formed is hardly 10 μm or more, the depth value C of the groove 22 is 10 μm or more. If formed so as to be less than D, the convex portion 3 a generated at the portion where the groove 22 is disposed can be completely accommodated in the groove 22.

  The grooves 22 do not overlap with the openings 11a of the channels 11 in any channel row, and are arranged at a distance from the edge 11b of the openings 11a, so that the grooves 22 and the grooves 22 as shown in FIG. Adhesive regions S1 and S1 are formed between the channel rows. For this reason, the groove 22 does not leak with the channel 11. In addition, the site | part by which the channel 11 is arrange | positioned in FIG. 3 was shown with the broken line.

  As shown in FIG. 3, the bonding regions S1 and S1 have a width corresponding to the shortest distance A from the edge 22a on the opening side (the bonding surface 2a side) of the groove 22 to the edge 11b of the opening 11a of the channel 11. Have. The grooves 22 are preferably arranged so that the shortest distance A is 50 μm or more. When the shortest distance A is less than 50 μm and the groove 22 and the channel 11 are close to each other, it is difficult for the adhesive to flow between the groove 22 and the channel 11 due to capillary force, and as shown in FIG. There is a possibility that an air portion X having no adhesive is easily generated between the groove 22 and the channel 11, and leakage occurs between the groove 22 and the channel 11. However, by setting the shortest distance A to 50 μm or more, the adhesive regions S1 and S1 can be wide enough to seal between the groove 22 and the channel 11 with an adhesive. For this reason, there is no possibility that the sealing failure of the channel 11 due to the shortage of the adhesion region will occur.

  Since the groove 22 functions as a glue guard that receives excess adhesive, the flow of the adhesive into the nozzle 21 can be suppressed. Since the groove 22 is arranged between the two channel rows of the head chip 1, even if the channel 11 becomes dense and the interval between the adjacent channels 11 and 11 in the same channel row becomes close, the surplus is provided. Grooves 22 can be formed with a volume sufficient to accept the adhesive.

  The groove width B (see FIGS. 3 and 6) on the opening side of the groove 22 is preferably as large as possible. Preferably, the shortest distance A is 50 μm or more and the groove width B is made as large as possible. Since the groove 22 can be widened and a large amount of surplus adhesive can be received at the same time, a region where the convex portion 3a can be accommodated can be widened, so that the nozzle plate 2 can be lifted by the convex portion 3a. The suppression effect can be enhanced.

  The grooves 22 extend linearly along the channel row direction, and may be formed at least from the nozzle 21 at one end of the nozzle row to the nozzle 21 at the other end. As shown, the end 22 b of the groove 22 is preferably communicated to the outside at the end of the nozzle plate 2. As a result, the end 22b of the groove 22 opens to the end surface 2b intersecting the nozzle row direction of the nozzle plate 2 and the inside of the groove 22 communicates with the outside air, so that the air in the groove 22 can escape from the end 22b. As a result, the surplus adhesive can be easily introduced.

  Here, both end portions 22b and 22b of the groove 22 are communicated to the outside from the end surface 2b of the nozzle plate 2, respectively. However, at least one end portion 22b of the groove 22 extends from the end surface 2b of the nozzle plate 2 to the outside. It only has to communicate.

  Further, the groove 22 is not limited to a single groove continuous in the channel row direction, and is divided into a plurality of grooves 22, 22... In the channel row direction as shown in FIG. Also good. FIG. 5 is a rear view of the nozzle plate 2 as viewed from the bonding surface 2a side, and a plurality of grooves 22, 22... Moreover, the site | part by which the channel 11 is arrange | positioned was shown with the broken line.

  The plurality of grooves 22, 22... Are arranged between two channel rows along the channel row direction. Between the adjacent grooves 22, 22, connecting portions 221, 221... For connecting the adhesive surfaces 2 a, 2 a that are divided vertically in the figure with the grooves 22, 22. ing. The surfaces of the connecting portions 221, 221... Are also adhesive surfaces with the head chip 1. The widths of the connecting portions 221, 221... Are sufficiently narrow compared to the grooves 22.

  According to this nozzle plate 2, in addition to the above effects, a plurality of connecting portions 221, 221... Are formed. An excessive bending can be prevented, and the effect of improving the handleability can be obtained. In addition, since the surfaces of the plurality of connecting portions 221, 221.

  In the present invention, as shown in FIG. 6, the groove 22 is formed in a tapered shape in which the groove width becomes narrower from the edge 22a, 22a on the opening side (adhesive surface 2a side) toward the bottom surface 22d of the groove 22. It is preferable to have wall surfaces 22c and 22c. By having the tapered side wall surfaces 22c and 22c in this manner, the angle θ formed by the adhesive surface 2a and the side wall surfaces 22c and 22c across the edge 22a becomes a relatively obtuse angle of less than 90 °. The excess adhesive between 1 and the nozzle plate 2 can easily flow into the groove 22 from the edge portions 22a and 22a, and the effect of receiving the excess adhesive can be further enhanced.

  The angle θ is not particularly limited, but is preferably 110 ° to 150 °.

  The tapered side wall surface 22c in the groove 22 only needs to be in a portion adjacent to the bonding surface 2a across the edge portion 22a. Accordingly, as shown in FIG. 7A, the side of the bottom surface 22d further than the tapered side wall surfaces 22c, 22c does not necessarily have to be tapered.

  Further, from the viewpoint of enhancing the effect of receiving excess adhesive, the tapered side wall surface 22c is preferably formed on both side walls of the groove 22, but as shown in FIG. A tapered side wall surface 22c may be formed only on one side wall surface.

  Further, the bottom surface 22d side of the tapered side wall surface 22c may be formed to have a shape in which the groove width is larger than the tapered portion, as shown in FIG. 7C.

  In addition, as shown in FIGS. 1 to 3 and FIG. 5, in addition to the grooves 22, the nozzle plate 2 has one groove (second groove) 23 in each of the portions outside the channel rows, 23 is formed. This groove 23 can also function as a so-called glue guard that accepts an excess of the adhesive applied between the head chip 1 and the nozzle plate 2, and is a preferred embodiment in the present invention. The groove 23 does not overlap the opening 11a of the channel 11, is disposed at a distance from the edge 11b of the opening 11a, and extends linearly along the channel row direction with a predetermined width and depth. Is formed.

  The depth of the groove 23 is preferably the same as the depth of the groove 22 so that the convex portion can be received in the same manner as the groove 22, and the head chip extends from the edge 23 a on the opening side of the groove 23. The shortest distance A ′ (see FIG. 3) to the edge 11b of the opening 11a of one channel 11 can also ensure sufficient adhesion regions S2 and S2 between them to ensure the sealing around the channel 11 From a viewpoint of making it, it is preferable that it is 50 micrometers or more.

  In order to facilitate the reception of the surplus adhesive, the groove 23 also has at least one of both end portions 23b and 23b opened to the end surface 2b of the nozzle plate 2 and communicated with the outside. In addition, like the groove 22 shown in FIGS. 6 and 7A to 7C, it is also preferable to have a tapered side wall surface to facilitate the flow of excess adhesive.

  Moreover, the groove | channel 23 can also be formed so that it may notch over the end surface 2c along the nozzle row direction of the nozzle plate 2, as shown in FIG. Thereby, the area | region of the groove | channel 23 can be taken widely. Since the end on the end surface 2c side of the nozzle plate 2 is thin, it is bonded to the end surface 1a of the head chip 1 while being bent as shown in the figure. In this case, since the adhesion region S2 is secured on the nozzle 21 side with respect to the groove 23, the sealing around the channel 11 is not affected.

  As the nozzle plate material, a known material can be used as appropriate, but it is preferable that the nozzle plate material is made of resin from the viewpoint of easy groove processing. Generally, polyimide can be used as the resin.

  The method for groove processing in the nozzle plate 2 is not particularly limited, and a known method such as laser processing or etching processing can be employed as appropriate.

  The adhesive used for bonding the head chip 1 and the nozzle plate 2 is not particularly limited, and either a thermosetting adhesive or a room temperature curable adhesive can be used. In the adhesive, particles having a particle diameter of 1 μm to 3 μm may be mixed so that minute irregularities on the end surface 1 a of the head chip 1 can be absorbed. The particles may be metal particles or resin particles. The particle size is defined by the volume average particle size.

(Second Embodiment)
FIG. 9 shows a second embodiment of the ink jet head according to the present invention, and is a perspective view showing left and right developed on the adhesive surface between the nozzle plate and the head chip. FIG. 10 shows the ink jet head shown in FIG. FIG. 11 is an end view showing the same cut end surface as that shown in FIG. 10, and FIG. 12 is a partial rear view of the nozzle plate. 1 and 2 have the same configuration, and therefore, the description of FIGS. 1 and 2 is used here and is omitted here. Note that the adhesive is not shown in FIGS.

  This nozzle plate 2 is different from the first embodiment in that the first groove provided on the bonding surface 2 a with the head chip 1 is formed by two parallel grooves 22, 22.

  These two grooves 22 and 22 can also function as so-called glue guards that receive the excess adhesive applied between the head chip 1 and the nozzle plate 2, and have a predetermined width and a predetermined depth. It extends in a straight line along the direction and is formed in parallel. None of the grooves 22 and 22 overlaps the opening 11a of the channel 11 of the channel row, and the groove 22 and 22 are disposed at a distance from the edge 11b of the opening 11a, thereby being bonded to the channel row. Regions S1 and S1 are formed. The value of the depth C of each groove 22, 22 is also equal to or greater than the value of the roughness Yp of the end surface 1a of the head chip 1 to which the nozzle plate 2 is bonded.

  In the nozzle plate 2, when the convex portion 3 a is positioned in the grooves 22, 22, the convex portion 3 a can be received in the groove 22 as shown in FIG. 10. For this reason, similarly to the case of FIG. 2, it is possible to prevent the nozzle plate 2 from being lifted by the convex portions 3 a, and the same effects as those of the first embodiment can be obtained.

  Even if the convex portion 3a is positioned between the grooves 22 and 22 of the nozzle plate 2, there is no problem that the nozzle 21 and the groove 22 leak as described below.

  That is, since the nozzle plate 2 is formed with the linear thin portions 2e and 2e along the grooves 22, 22, the nozzle plate 2 can be easily bent along the thin portions 2e and 2e. For this reason, when the convex part 3a is located between the grooves 22 and 22, as shown in FIG. 11, only the nozzle plate part 2d between the grooves 22 and 22 in contact with the convex part 3a becomes the thin parts 2e and 2e. It bends along and is lifted so as to lift from the head chip 1. However, the adhesion regions S1, S1 between the grooves 22, 22 and the channel row can be in close contact with the head chip 1 without being affected at all by the rise of the nozzle plate portion 2d. Therefore, there is no problem that the groove 22 and the channel 11 leak.

  By providing the plurality of grooves 22 between the channel rows in this way, it is possible to suppress a decrease in the strength of the nozzle plate 2 compared to the case where only one wide groove is provided. Further, since the thin portion 2e is also narrow, the handleability of the nozzle plate 2 is improved as compared with the case where only one wide groove is provided. In addition, since the bonding area of the nozzle plate 2 between the channel rows can be increased as compared with the case where only one wide groove is provided, a decrease in the bonding strength can be suppressed. Furthermore, groove processing is easier than forming wide grooves.

  As shown in FIG. 12, the shortest distance A from the outer edge 22a on the opening side (adhesive surface 2a side) of the groove 22 to the edge 11b of the opening 11a of the channel 11 is also the first distance A. For the same reason as in the embodiment, the thickness is preferably 50 μm or more. In FIG. 12, the portion where the channel 11 is arranged is indicated by a broken line.

  It is preferable that at least one of the end portions 22b and 22b of the grooves 22 and 22 is open to the end surface 2b of the nozzle plate 2 and communicates with the outside in order to facilitate the reception of excess adhesive. .

  Further, as shown in FIG. 13, the parallel grooves 22, 22 may be connected by a connecting groove 222. FIG. 13 is a rear view of the nozzle plate 2 as viewed from the bonding surface 2a side, and the grooves 22, 22, the connecting groove 222, and the groove 23 are indicated by hatching. Moreover, the site | part by which the channel 11 is arrange | positioned was shown with the broken line.

  A plurality of connecting grooves 222 are formed with the same width and the same depth as the grooves 22 and spaced in the channel row direction so as to connect the two grooves 22, 22. Thus, an independent island-like nozzle plate portion 2d surrounded by the grooves is formed between the adjacent connecting grooves 222, 222.

  According to this nozzle plate 2, in addition to the above effects, the nozzle plate portion 2 d between the two grooves 22, 22 is formed in an island shape, so even if it contacts the convex portion 3 a between the grooves 22, 22. Only the island-shaped nozzle plate portion 2 d in contact with the convex portion 3 a needs to be lifted from the head chip 1, and the other island-shaped nozzle plate portion 2 d is in close contact with the head chip 1. Therefore, the adhesive strength of the nozzle plate 2 can be improved.

  It is also preferable that the grooves 22 and 22 and the connecting groove 222 have a tapered side wall surface similar to the side wall surface 22c of the groove 22 shown in the first embodiment. The same shape as that shown in FIGS. 6 and 7 can be applied.

  The grooves 22 and 22 are not limited to the two illustrated, but may be formed to be three or more according to the space between the channel rows. It is possible to increase the amount of excess adhesive received.

  When a plurality of grooves 22 are formed in the nozzle plate 2 in this way, assuming that the groove width of the groove 22 is B, the thickness of the nozzle plate 2 is D, and the depth of the groove 22 is C, B> D−C It is preferable to satisfy the following condition. Since the thin portion 2e is sufficiently thin with respect to the groove width of the groove 22, the nozzle plate portion 2d between the grooves 22 and 22 can be more easily bent at the portions of the thin portions 2e and 2e. Sealing between the channel rows can be further ensured.

(Other embodiments)
In the ink jet head described above, the parylene film 3 is formed on the surface of the head chip 1, but the parylene film 3 is not necessarily provided in the present invention. Even when the parylene film 3 is not coated, foreign matters such as dust adhere to the end surface 1a, or the cut surface when the head chip 1 is cut out becomes a rough surface, so that the end surface 1a has the same convexity as the convex portion 3a. There is a possibility that the nozzle plate 2 may float due to the occurrence of a portion, and the same effect as described above can be obtained by applying the present invention.

  Further, although the ink jet head described above has been exemplified as having two channel rows (two nozzle rows), the ink jet head according to the present invention has three or more channel rows (nozzle rows). May be. Therefore, as shown in FIG. 14, for example, an inkjet head having six nozzle rows can be provided. In FIG. 14, the grooves 22 shown in the first embodiment are formed between the nozzle rows, but it is needless to say that the plurality of grooves 24 shown in the second embodiment may be formed.

  In the above description, all the channels 11 of the head chip 1 are illustrated as drive channels for ejecting ink. However, one channel row includes a drive channel for ejecting ink and a dummy channel for not ejecting ink. It may be arranged alternately.

  Further, in the above description, the example having the head chip 1 in which the drive wall 12 between the adjacent channels 11 and 11 is deformed to eject ink is illustrated. However, in the present invention, a plurality of pressure chambers are arranged. An ink jet head having a head chip in which a plurality of rows of pressure chambers arranged in parallel and a nozzle plate bonded to the end surface of the head chip on the outlet side of the pressure chamber by an adhesive. That's fine. For example, one wall surface of the pressure chamber may be constituted by a vibration plate, and may have a head chip in which the vibration plate is vibrated by a piezoelectric material to discharge ink, and a heater is provided in the pressure chamber. The heater may have a head chip that generates bubbles in the ink in the pressure chamber and discharges the ink by the bursting action of the bubbles.

  A head chip and a nozzle plate having the following specifications were prepared. The head chip has a hexahedron shape similar to that in FIG. 1, and channels and drive walls are alternately arranged to form one channel row, and the drive walls are sheared to discharge ink in the channels from the nozzles. It is a head chip. The nozzle plate was made of polyimide, and nozzles were formed at positions corresponding to the respective channels.

<Head chip>
Channel width: 60 μm
Channel depth E: 200 μm
L length (length in channel discharge direction): 1.5 mm
Channel pitch: 127 μm
Number of channel rows: 2 rows Distance F between channel rows F: 928 μm
Number of channels / column: 592

<Nozzle plate>
Thickness D: 75 μm
Nozzle outlet diameter: 22 μm

(Examples 1 and 2 and Comparative Examples 1 and 2)
For Examples 1 and 2 and Comparative Examples 1 and 2 shown in Table 1, the same epoxy adhesive was applied to the adhesive surface of the head chip so as to have the same thickness, and then 10 inkjet heads were bonded to the nozzle plate. I got one by one.

  A parylene film with a thickness of 10 μm was formed on the surface of each head chip before bonding the nozzle plate. After the formation of the parylene film, for each head chip, the surface roughness of the entire bonding surface with the nozzle plate is measured three-dimensionally using a shape measurement laser microscope (Keyence: VK-X100). When the roughness Yp was determined, all head chips were within the range of 6 μm to 10 μm.

  Except for the ink jet head of Comparative Example 1, only one groove was formed in the nozzle plate at a portion facing between the channel rows as in FIG. The specifications of the groove are shown in Table 1.

  The dimensions of the nozzle plate (NP dimension) are: A: shortest distance from the edge of the groove to the edge of the opening on the outlet side of the channel, B: groove width, C: groove depth, D: nozzle plate (Both unit: μm).

  For each of the inkjet heads of Examples 1 and 2 and Comparative Examples 1 and 2, nozzle clogging due to adhesive and leakage between channels due to foreign matter (convex parts) are inspected, and the defect occurrence rate is determined as defective nozzles per head chip. Rated by number. The results are shown in Table 1.

  Nozzle clogging was judged by visually inspecting the nozzles of each inkjet head with a microscope.

In addition, leakage due to foreign matter is visually inspected with a microscope for the presence of a gap (bubble) between the nozzle plate and the head chip, and if there is a gap, it is determined whether the gap communicates between the channels. It was judged that there was a leak.

  From Table 1, compared with Comparative Example 1 in which no groove was formed, in Examples 1 and 2 in which the groove was formed, the occurrence of nozzle clogging due to the flow of the adhesive into the nozzle decreased.

  In contrast to Comparative Example 1 in which no groove is formed and Comparative Example 2 in which depth C is less than the roughness Yp, in Examples 1 and 2 in which a groove having a depth equal to or greater than the roughness Yp is formed. In both cases, the occurrence rate of leakage failure due to foreign matter has been reduced, and the effect of the present invention has been demonstrated.

(Examples 2 to 6)
In addition to the second embodiment described above, ten ink jet heads of the third to sixth embodiments in which only A in the NP dimension in the second embodiment is changed as shown in Table 2 are provided in the same manner as in the second embodiment. Obtained.

  A parylene film having a thickness of 10 μm was also formed on the surface of each head chip of Examples 3 to 6 before bonding the nozzle plate. After the formation of the parylene film, for each head chip, the surface roughness of the entire bonding surface with the nozzle plate is measured three-dimensionally using a shape measurement laser microscope (Keyence: VK-X100). When the roughness Yp was determined, all head chips were within the range of 6 μm to 10 μm.

  In Examples 2 to 6, in addition to nozzle clogging and leakage due to foreign matter as described above, leakage between grooves and channels formed in the nozzle plate is inspected, and the defect occurrence rate is similarly determined by the number of defective nozzles per head chip. evaluated. The results are shown in Table 2.

For leakage between the groove and the channel, visually inspect the presence of bubbles between the groove and the channel with a microscope, and if there are bubbles, determine whether the bubbles communicate with the channels and the channels. It was judged that there was a leak.

  From Table 2, Examples 3 to 6 also have a low incidence of nozzle clogging and leakage due to foreign matter, but A (the shortest distance from the edge of the groove to the edge of the opening on the outlet side of the channel) In Examples 4 to 6 in which the distance) was 50 μm or more, no leakage between the groove and the channel was observed.

(Examples 7 to 12)
About Examples 7-12 shown in Table 3, after apply | coating the same epoxy adhesive so that it might become the same thickness to the adhesion surface of a head chip, 10 inkjet heads which adhered the nozzle plate were obtained, respectively. In the nozzle plate, two parallel grooves were respectively formed at portions facing the channel rows in the same manner as in FIG. Table 3 shows the specifications of the grooves.

  A parylene film having a thickness of 10 μm was also formed on the surface of each head chip before bonding the nozzle plate. After the formation of the parylene film, for each head chip, the surface roughness of the entire bonding surface with the nozzle plate is measured three-dimensionally using a shape measurement laser microscope (Keyence: VK-X100). When the roughness Yp was determined, all head chips were within the range of 6 μm to 10 μm.

  For each of the inkjet heads of Examples 7 to 12, nozzle clogging, leakage due to foreign matter, and leakage between the groove and the channel are inspected in the same manner as described above, and the defect occurrence rate is evaluated based on the number of defective nozzles per head chip. did. The results are shown in Table 3.

  From Table 3, Examples 7 to 12 also have a low failure occurrence rate due to nozzle clogging and foreign matter, but Examples 10 to 12 satisfying B + C−D> 0 do not satisfy this. Compared to 9, the defect occurrence rate of leakage due to foreign matter was further reduced.

  In all of Examples 7 to 12, when A (the shortest distance from the edge of the groove to the edge of the opening on the outlet side of the channel) is 50 μm or more, the occurrence of leakage between the groove and the channel is I couldn't see it.

1: Head chip 1a: End face 11: Channel (pressure chamber)
11a: Opening portion on the exit side 11b: Edge portion 12: Drive wall 2: Nozzle plate 2a: Adhesive surface 2b, 2c: End surface 2d: Nozzle plate portion 2e: Thin portion 21: Nozzle 22: Groove (first groove)
221: Connecting portion 222: Connecting groove 22a: Edge portion 22b: End portion 22c: Side wall surface 22d: Bottom surface 23: Groove (second groove)
23a: Edge part 3: Parylene film 3a: Convex part S1, S2: Adhesion area X: Air part

Claims (12)

A head chip in which a plurality of rows of pressure chambers in which a plurality of pressure chambers are arranged are arranged side by side, and a nozzle plate bonded to an end surface of the head chip on which an opening on the outlet side of the pressure chamber is disposed by an adhesive. In an inkjet head having
The nozzle plate has a first groove formed along the row of pressure chambers at a portion corresponding to the space between the rows of pressure chambers on the bonding surface with the head chip.
The depth value of the first groove is equal to or greater than the roughness value of the end face of the head chip to which the nozzle plate is bonded ;
The inkjet head according to claim 1, wherein the first groove has a shortest distance of 50 μm or more from the edge of the first groove to the edge of the opening on the outlet side of the pressure chamber . It said first groove, claim 1 Symbol placement inkjet head, characterized in that it is divided into a plurality of column direction of the pressure chamber.   2. The ink jet head according to claim 1, wherein two or more of the first grooves extend along the rows of the pressure chambers at portions corresponding to the rows of the pressure chambers. . A head chip in which a plurality of rows of pressure chambers in which a plurality of pressure chambers are arranged are arranged side by side, and a nozzle plate bonded to an end surface of the head chip on which an opening on the outlet side of the pressure chamber is disposed by an adhesive. In an inkjet head having
The nozzle plate has a first groove formed along the row of pressure chambers at a portion corresponding to the space between the rows of pressure chambers on the bonding surface with the head chip.
The depth value of the first groove is equal to or greater than the roughness value of the end face of the head chip to which the nozzle plate is bonded;
2. The inkjet head according to claim 1, wherein two or more of the first grooves extend along the rows of the pressure chambers at portions corresponding to the rows of the pressure chambers . B the groove width of the first groove, the depth C of the first groove, when the thickness of the nozzle plate and is D, claim 3 or 4, characterized in that a B> D-C The inkjet head as described. 6. The ink jet head according to claim 3, further comprising a connecting groove that connects the adjacent first grooves.   The inkjet head according to claim 1, wherein the first groove communicates with an outside of the nozzle plate at an end portion of the nozzle plate.   The inkjet head according to claim 1, wherein the first groove has a side wall surface formed in a tapered shape. A head chip in which a plurality of rows of pressure chambers in which a plurality of pressure chambers are arranged are arranged side by side, and a nozzle plate bonded to an end surface of the head chip on which an opening on the outlet side of the pressure chamber is disposed by an adhesive. In an inkjet head having
The nozzle plate has a first groove formed along the row of pressure chambers at a portion corresponding to the space between the rows of pressure chambers on the bonding surface with the head chip.
The depth value of the first groove is equal to or greater than the roughness value of the end face of the head chip to which the nozzle plate is bonded;
Said first groove, wherein a to Louis inkjet head that has a side wall surface formed in a tapered shape. Wherein the adhesive, the ink-jet head according to any one of claims 1 to 9, characterized in that particles having a particle size 1μm~3μm are mixed. Said head chip, the inkjet head according to any one of claims 1 to 10, characterized in that parylene film is coating treatment to the end face of the head chip in which the nozzle plate is bonded. The inkjet head according to any one of claims 1 to 11, wherein the nozzle plate is characterized in that it is made of resin.

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