JP5428291B2 - Multi-chip inkjet head - Google Patents

Description

  The present invention relates to a multi-chip inkjet head, and more particularly to a multi-chip inkjet head formed by positioning and arranging a plurality of head chips on the surface of a single wiring board.

  Normally, when an inkjet head is lined to be elongated along the channel arrangement direction, if an inkjet head is configured using a single wide head chip (actuator) having a desired line width, the width There is a problem that it is very difficult to produce a head chip having uniform injection characteristics in the direction, and it is also very difficult to process the head chip uniformly in the width direction. Furthermore, since it is necessary to store several thousand to several tens of thousands of nozzles in one head, it is disadvantageous in terms of yield, and it is very disadvantageous in the bonding process due to the influence of thermal expansion. For this reason, conventionally, by using a plurality of head units created using narrow-width head chips and arranging them in a staggered manner on one mounting member so as to have a desired line width, It is common to create an inkjet head (Patent Document 1).

  The head unit is an ink jet head that can perform printing by ink ejection alone.

  However, in the case of an inkjet head created using a plurality of such head units, it is difficult to suppress the printing variation of each head unit, and it is difficult to ensure the landing position accuracy of the ink in the entire inkjet head. There is a problem that there is.

  That is, since a plurality of head units are arranged on one mounting member, not only the alignment accuracy of each head unit, but also the alignment of the nozzle plate possessed by each head unit and the processing for creating nozzles in the nozzle plate In addition to the nozzle position accuracy, which incorporates variations due to accuracy, etc., variations in the characteristics of the actuators of each head unit are added, leading to large variations in printing throughout the inkjet head, resulting in mounting position accuracy and mounting angle. There is a problem that image defects are likely to occur due to accuracy and speed unevenness.

  In addition, when a long or large inkjet head is configured using a plurality of head units, one head unit usually supplies ink to wirings, substrates, and head chips connected to the head chip in addition to the head chip. Therefore, since the outer shape of the manifold is larger than that of the head chip, it is difficult to make the interval between adjacent head units compact. For this reason, there is a problem that the inkjet head becomes larger than necessary.

Furthermore, a supply pipe for supplying ink individually to each of a plurality of head units provided for one long or large ink jet head must be provided, and the piping structure is complicated and the piping work is complicated. There is also a problem that the operation of connecting the FPC for applying the driving voltage to each of the head units is complicated.
Japanese Patent Laid-Open No. 2002-292873 JP 2008-6792 A JP 2007-83705 A

  Therefore, the present invention makes it possible to reduce the cause of variations in printing and make it difficult to generate image defects when the inkjet head is lengthened or enlarged, and the inkjet head can be made compact and the ink supply can be reduced. It is an object of the present invention to provide a multi-chip ink jet head that can simplify the connection of piping and FPC for applying a driving voltage.

  The other subject of this invention becomes clear by the following description.

  The above problems are solved by the following inventions.

According to the first aspect of the present invention, drive walls and channels made of piezoelectric elements are alternately arranged side by side, outlets and inlets of the channels are arranged on the front and rear surfaces, respectively, drive electrodes are formed on the drive walls, and A multi-chip inkjet head that has a plurality of head chips each having a connection electrode electrically connected to the drive electrode on the rear surface, and discharges ink in the channel from the nozzle by applying a drive voltage to the drive electrode. There,
A plurality of the head chips are formed on a single wiring substrate having wiring electrodes corresponding to the connection electrodes of the head chips formed on the surface and an ink introduction communication port corresponding to the head chip being opened. The connection electrode and the wiring electrode are electrically connected, and the channel inlet of the head chip is positioned and bonded so as to face the communication port for introducing the ink; and
A single nozzle plate having a nozzle hole formed at a position corresponding to the channel of all the head chips is attached to the front surface of all the head chips,
One ink manifold for supplying ink in common to all the head chips through the ink introduction communication port is joined to the back surface side of the wiring board ,
The plurality of head chips are multi-chip inkjet heads characterized in that head chips cut out from different wafers are arranged adjacent to each other .

According to a second aspect of the present invention, driving walls and channels made of piezoelectric elements are alternately arranged side by side, outlets and inlets of the channels are arranged on the front and rear surfaces, respectively, driving electrodes are formed on the driving walls, A multi-chip inkjet head that has a plurality of head chips each having a connection electrode electrically connected to the drive electrode on the rear surface, and discharges ink in the channel from the nozzle by applying a drive voltage to the drive electrode. There,
A plurality of the head chips are formed on a single wiring substrate having wiring electrodes corresponding to the connection electrodes of the head chips formed on the surface and an ink introduction communication port corresponding to the head chip being opened. The connection electrode and the wiring electrode are electrically connected, and the channel inlet of the head chip is positioned and bonded so as to face the communication port for introducing the ink; and
A single nozzle plate having a nozzle hole formed at a position corresponding to the channel of all the head chips is attached to the front surface of all the head chips,
One ink manifold for supplying ink in common to all the head chips through the ink introduction communication port is joined to the back surface side of the wiring board,
A spacer member having a height from the surface of the wiring board equal to the height of the front surface of the head chip is provided between the plurality of head chips, and one nozzle plate is connected to the front surfaces of all the head chips. It is a multichip inkjet head characterized by sticking over the surface of the spacer member .

A third aspect of the invention is the multi-chip inkjet head according to the second aspect, wherein the plurality of head chips are arranged so that head chips cut from different wafers are adjacent to each other .

According to a fourth aspect of the present invention, the wiring electrode is formed from the communication port for introducing ink corresponding to the connection electrode of the head chip to an outer end portion of the wiring substrate, and an outer end of the surface of the wiring substrate. 4. The multi-chip inkjet head according to claim 1, wherein an FPC in which a wiring for transmitting a driving voltage from a driving IC is formed is electrically connected to the wiring electrode of the unit .

According to a fifth aspect of the present invention, a plurality of the head chips are arranged on the surface of the wiring board so that the pitches of the channels are equal to each other along the alignment direction of the channels and the adjacent head chips. A multi-chip inkjet head according to any one of claims 1 to 4, wherein a line-type inkjet head is formed by doing so.

According to a sixth aspect of the present invention, a positioning mark corresponding to each of the plurality of head chips is formed at a predetermined position on the surface of the wiring board, and each of the plurality of head chips is positioned by the positioning mark. It is a multichip inkjet head in any one of Claims 1-5 characterized by the above-mentioned.

According to a seventh aspect of the present invention, the positioning mark has a first linear pattern extending in a direction perpendicular to the channel arrangement direction of the head chip and having both outer edges parallel to each other.
The width of the first linear pattern is the same as the width of the first linear pattern across the front surface and the rear surface of the head chip at a position corresponding to the first linear pattern on the side surface in contact with the rear surface of the head chip, and , Straight grooves with parallel inner wall surfaces are processed,
When viewed from the front side of the head chip bonded to the surface of the wiring substrate, the inner wall surfaces facing each other in the groove appear to coincide with both outer edges of the first linear pattern. 7. The multi-chip inkjet head according to claim 6 , wherein each of the plurality of head chips is positioned.

The invention according to claim 8 is the multi-chip inkjet head according to claim 7 , wherein the first linear pattern is composed of two parallel linear patterns with a predetermined interval.

The invention according to claim 9, wherein the first linear pattern, according to claim 7, wherein the predetermined position of the surface of the wiring board, characterized in that it is patterned using the wiring same metal material as the electrode Or it is a multichip inkjet head of 8 .

The invention according to claim 10 is a pattern for positioning a side surface parallel to the channel arrangement direction of the head chip at a predetermined position on the surface of the wiring board, and is orthogonal to the first linear pattern. A second linear pattern having a linear portion is formed;
Positioned so that the outer edge of the rear surface of the head chip is seen to coincide with the linear portion of the second linear pattern when viewed from the front surface side of the head chip bonded to the surface of the wiring board. The multi-chip inkjet head according to claim 7 , 8 or 9 .

The invention according to claim 11, wherein the second linear pattern, according to claim 10, wherein the predetermined position of the surface of the wiring board, characterized in that it is patterned using the wiring same metal material as the electrode It is a multichip inkjet head of description.

  According to the present invention, driving walls and channels made of piezoelectric elements are alternately arranged on a single wiring board, and outlets and inlets of the channels are disposed on the front and rear surfaces, respectively, and driving electrodes are provided on the driving walls. A plurality of head chips formed and formed with connection electrodes electrically connected to the drive electrodes on the rear surface are positioned and arranged, and one nozzle plate is attached across the front surfaces of all the head chips, Since all the head chips share a nozzle plate, each head chip only needs to be bonded with a precision within a range that allows the nozzle holes formed in the nozzle plate and the respective channels to communicate with each other. Strict accuracy is not required for the mounting position of each head chip in order to ensure positional accuracy. For this reason, the only causes of variations in printing are variations due to processing accuracy when nozzle holes are formed in one nozzle plate and variations in characteristics of each head chip.

  In addition, since only a plurality of head chips are arranged on the surface of the wiring substrate, the length or size of the head chips can be increased, so that the positions of the head chips can be close to each other, and the entire inkjet head can be made compact.

  Further, an ink introduction communication port for supplying ink to each head chip is formed on the wiring board, and ink can be supplied to all the head chips from the back side of the wiring board. Work and piping structure can be simplified.

  In addition, since the drive voltage is applied to each head chip by FPC connection to the wiring electrodes formed on the same surface of the wiring substrate, the FPC connection work can be simplified.

  Therefore, when the ink jet head is lengthened or enlarged, it is possible to reduce the factors that cause the printing variation and make it difficult to generate image defects, and the ink jet head can be made compact, and the piping for supplying ink In addition, it is possible to provide a multi-chip inkjet head that can simplify the connection of an FPC for applying a driving voltage.

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

<Structure of multi-chip inkjet head>
Overall Structure FIG. 1 is an exploded perspective view showing a full-line type inkjet head showing an embodiment of a multi-chip inkjet head according to the present invention, FIG. 2 is a partial perspective view of one head chip viewed from the rear side, and FIG. 1 is a sectional view taken along line (iii)-(iii) in FIG. 1, and FIG. 4 is a sectional view taken along line (iv)-(iv) in FIG.

  The inkjet head H is configured by a large number of head chips 1 arranged in a staggered pattern on a wiring board 2. The wiring board 2 is formed in a long shape along the X direction in FIG. 1, and six head chips 1 are arranged on the surface so as to form two rows in the Y direction. The number of head chips 1 is as follows. There is no particular limitation. In the head chip 1, for example, channel rows in which drive walls 11 made of a piezoelectric element subjected to polarization processing such as PZT and channels 12 serving as ink chambers are alternately arranged in parallel are arranged in two rows in the vertical direction in FIG. 2. Are installed side by side.

  A spacer member 5 is formed on the surface of the wiring substrate 2 so that the height from the surface of the wiring substrate 2 is equal to the height of the front surface 1a of the head chip 1 between the plurality of head chips 1 arranged. It is glued.

  A single nozzle plate 3 is adhered across the front surface 1a of all the head chips 1 and the surface of the spacer member 5. In the nozzle plate 3, a large number of nozzle holes 31 communicating with the inside of the channel 12 are opened at positions corresponding to the channels 12 of the head chips 1.

  One ink manifold 6 for supplying ink in common to all the head chips 1 is joined to the back side of the wiring board 2 (the side opposite to the bonding surface of the head chip 1).

  The wiring board 2 has a size that protrudes to the side of the bonding area of the plurality of head chips 1 and the spacer member 5, and FPCs (flexible wiring boards) 7A and 7B are formed on the outer ends of the surface. Be joined. Each FPC 7A, 7B transmits a drive voltage from a drive IC (not shown) to a drive electrode 13 formed in each channel 12 of each head chip 1.

  Such an ink jet head H reduces the volume in the channel 12 by deforming the drive wall 11 made of a piezoelectric element into a U-shape by the drive voltage from the drive IC applied via the FPCs 7A and 7B, thereby reducing the nozzle hole. Ink is ejected from 31 in the Z direction in FIG.

  Note that XYZ are directions orthogonal to each other. In the present invention, in the head chip 1, the surface on the ink ejection side is referred to as “front surface 1 a”, and the opposite surface is referred to as “rear surface 1 b”. Further, the side surfaces located in the upper and lower directions in the figure across the channels 12 arranged in parallel in the head chip 1 are referred to as “upper surface 1 c” and “lower surface 1 d”, respectively. The front surface 1a and the rear surface 1b are substantially parallel, and the upper surface 1c and the lower surface 1d are substantially parallel.

Each head chip 1, which is the head chip plurality share the same construction, and has front 1a, a rear surface 1b, the upper surface 1c is a side that is sandwiched between them, a rectangular parallelepiped shape having a bottom surface 1d and two end surfaces 1e.

  The shape of each channel 12 in the head chip 1 is such that both side walls extend substantially perpendicular to the upper surface 1c and the lower surface 1d of the head chip 1 and are parallel to each other. On the front surface 1a and the rear surface 1b of the head chip 1, the front-side opening 121 and the rear-side opening 122 of each channel 12 face each other. Each channel 12 forms a so-called harmonica-type head chip structure that is a straight type whose size and shape do not substantially change in the length direction from the opening 122 on the rear surface side to the opening 121 on the front surface side.

  The head chip 1 shown in the present embodiment exemplifies a head chip having two channel rows each composed of a plurality of channels 12 arranged in parallel with the drive wall 11 interposed between the channel rows. These pitches are offset by a half pitch. In the present invention, since only the plurality of head chips 1 are arranged on the same surface of the wiring board 2, it is necessary to interpose another member (excluding the spacer member 5) such as an exterior member between the adjacent head chips 1. It is possible to bring the positions of the head chips 1 close to each other as close as possible. For this reason, even if a plurality of head chips 1 are arranged, the size of the inkjet head H can be made compact.

  A drive electrode 13 is formed in close contact with the entire inner surface of each channel 12 using a metal material such as Ni, Co, Cu, or Al. In the head chip 1, by applying a predetermined driving voltage to the driving electrode 13, the driving wall 11 is deformed into a V shape and the ink in the channel 12 is ejected from the nozzle hole 31.

  Further, on the rear surface 1 b of the head chip 1, a connection electrode 14 that is electrically connected to the drive electrode 13 in each channel 12 is an upper surface that is adjacent to each other from within each channel 12 by the same metal material as the drive electrode 13. It is drawn out toward the edge on the 1c side or the edge on the lower surface 1d side.

  On the upper surface 1 c of the head chip 1, linear position confirmation grooves 15 extending from the front surface 1 a and the rear surface 1 b of the head chip 1 are formed at positions outside the outermost channel 12. The position confirmation groove 15 is also formed outside the channel 12 on the opposite outermost end not shown in FIG.

  FIG. 5 shows an enlarged portion of one position confirmation groove 15. As shown in the figure, the opposing inner wall surfaces 151, 151 in the position confirmation groove 15 are parallel to each other and intersect at right angles to the upper surface 1 c of the head chip 1.

  As will be described in detail later, the position confirmation groove 15 is used when positioning the head chip 1 by making it correspond to the first linear pattern of the positioning mark 4 formed on the surface of the wiring board 2. Prior to cutting out the plurality of head chips 1 from a single wafer, the head chips 1 are previously ground by a dicing saw so as to have a constant depth over the entire length of the groove.

  The width (the distance between the inner wall surfaces 151 and 151) is formed to be the same as the width of the outer edge of the first linear pattern to be described later, so that image recognition during positioning can be performed easily. In view of the efficiency, and considering the efficiency at the time of processing, the blade width of the dicing saw used for cutting the wafer outer shape is preferably set equal to 0.2 to 1 mm. The depth is preferably about 1 to 2 times the aforementioned width.

The wiring substrate wiring substrate 2 is formed in a rectangular shape by a plate-like substrate made of a ceramic material such as non-polarized PZT, AlN-BN, or AlN. Further, glass, polyimide LCP, or the like can be used as the substrate material. As the glass, Pyrex (registered trademark) or Tempax (registered trademark), in which the thermal expansion coefficient of the piezoelectric material is substantially the same, can be preferably used. The material constituting the wiring board 2 is not limited to a single plate, and a plurality of thin plate-like substrate materials may be stacked to form a desired thickness.

  The wiring board 2 shown in the present embodiment has a width that is at least larger than the width in which the head chips 1 can be arranged in two rows along the Y direction, and a direction (Y direction) orthogonal to the channel row direction (X direction). The outer end portions 21A and 21B are extended to extend greatly. The outer end portions 21A and 21B are connection portions for electrical connection with the FPCs 7A and 7B, respectively.

  FIG. 6 shows a part of the surface of the wiring board 2 before the head chip 1 is bonded. As shown in the figure, the ink introduction communication ports 22 extending along the channel row direction of the head chips 1 are respectively provided at positions corresponding to the portions where the head chips 1 are arranged in a staggered manner and joined. Openings are individually formed so as to correspond to each of the plurality of head chips 1.

  The ink introduction communication port 22 serves as a flow path for supplying the ink in the ink manifold 6 joined to the back surface side of the wiring board 2 into each channel 12 of the head chip 1. Each communication port 22 for introducing ink has an opening area that is smaller than the area of the rear surface 1b of one corresponding head chip 1 and that can accommodate all the channels 12 that open to the rear surface 1b. doing.

  The ink introduction communication port 22 can be formed by machining by an end mill, machining by laser, or sandblasting. From the viewpoint of mass productivity and ease of processing, processing by sandblasting is preferable. According to the processing by sand blasting, it is easy to form not-shown holes and recesses used for external punching of the wiring board 2 and positioning of the ink manifold 6 in addition to the ink introduction communication port 22. There is also.

  Since it is necessary to accurately process the ink introduction communication port 22, it is preferable to perform processing from both surfaces of the wiring board 2 in the case of processing by sandblasting. In this case, a concave portion larger than a desired hole diameter is created from the back surface side where the wiring electrode 23 described later is not formed, and thereafter, processing is performed from the front surface side where the wiring electrode 23 is formed so as to pass through, so Processing accuracy can be obtained.

  The wiring electrodes 23 are formed on the surface of the wiring substrate 2 at the same number and pitch as the connection electrodes 14 of each head chip 1 so as to correspond to the connection electrodes 14 formed on the rear surface of the head chip 1.

  In the figure, a plurality of wiring electrodes corresponding to one channel row of one head chip 1 are collectively indicated by reference numeral 23.

  Each of the wiring electrodes 23 is patterned by a plating method, a sputtering method, a vapor deposition method or the like using the same metal material as that of the drive electrode 13 and the connection electrode 14. From the viewpoint of cost and handling, sputtering or vapor deposition using Al as the metal material is preferable.

  In this embodiment, since the head chip 1 has two channel rows, the wiring electrodes 23 corresponding to one head chip 1 are electrically connected to the connection electrodes 14 of the channels 12 of each channel row. The wiring board 2 is formed to extend to both outer end portions 21A and 21B. That is, the wiring electrode 23 corresponding to one head chip 1 is formed from the two opening edges 22a, 22b on the long side of the corresponding ink introduction communication port 22 or from the vicinity thereof to the outer ends 21A, 21B. When the rear surface 1b of each head chip 1 is properly positioned and bonded to the surface of the wiring board 2, the head electrodes 1 are electrically connected to the corresponding connection electrodes 14 in a one-to-one relationship. The wiring electrodes 23 protruding from the head chips 1 toward the outer end portions 21A and 21B are exposed on the surface of the wiring board 2, and the exposed portions serve as connection portions for connecting the FPCs 7A and 7B, respectively.

  The opening edge 22a is located on the same side as one outer end portion 21A of the wiring board 2, and the opening edge 22b is located on the same side as the other outer end portion 21B of the wiring board 2.

Nozzle plate Nozzle plate 3 has a size that can cover all the head chips 1 bonded to the surface of the wiring board 2 and the surface of the spacer member 5 provided between the head chips 1. It is made of a sheet material. As this material, in addition to resin materials such as polyimide, polyethylene terephthalate, polyamide, and polysulfone, silicon having a linear expansion coefficient close to that of PZT can be used.

  In the nozzle plate 3, the nozzle holes 31 are formed with high precision by laser processing at positions corresponding to the respective channels 12 of all the head chips 1 before being attached to the head chip 1 and the spacer member 5. The nozzle plate 3 in which the nozzle holes 31 have been processed is applied to the surface of the head chip 1 and the spacer member 5 after all the head chips 1 and the spacer members 5 are bonded to the surface of the wiring board 2. Then, the nozzle holes 31 and the channels 12 are aligned and attached using an adhesive.

  One of the factors that cause the printing variation of the inkjet head is the mounting position deviation between the adjacent head chips 1, and when a plurality of head units are arranged as in the prior art, it is usually over all the head units. In order to make the nozzle pitches equal, strict accuracy is required for the mounting positions of adjacent head units. In the present invention, however, the nozzle plate 3 is shared by a plurality of head chips 1 arranged, and all nozzle holes are arranged. 31 is formed in advance on one nozzle plate 3, the pitch of all nozzle holes 31 is processed with high accuracy depending on the processing accuracy of the nozzle holes 31, and the pitch is uniform over all head chips 1. The mounting position accuracy of the plurality of head chips 1 is such that each channel 12 and the nozzle hole 31 can correspond. Ri, individual exact mounting position accuracy of the head chip 1 is not required.

The spacer member 5 is for filling the gap between the adjacent head chips 1 on the wiring board 2 and is formed at the same height as the height from the surface of the wiring board 5 to the front surface 1 a of the head chip 1. Thus, the front surface 1a of all the head chips 1 and the surface of the spacer member 5 are formed so as to be in the same rectangular plane in plan view.

  The spacer member 5 may be formed as one integral spacer member 5 across all the head chips 1 as shown in the figure, but may be divided into a plurality of pieces.

  Use of unpolarized PZT, glass, LCP (liquid crystal polymer member), AlN (aluminum nitride), etc. as the material of the spacer member 5 is close to the linear expansion coefficient with the head chip 1 and maintains high accuracy. Among these, it is preferable to use PZT from the viewpoint of workability.

  The spacer member 5 in the present invention is for filling a gap formed after the plurality of head chips 1 are arranged as necessary, and has any influence on the mounting position of the adjacent head chip 1. There is no. Moreover, the spacer member 5 does not necessarily need to be provided if there is no problem in sticking the nozzle plate 3 so as to have a smooth surface.

The ink manifold ink manifold 6 has a box shape having an opening 61 that can surround all the ink introduction communication ports 22 formed in the wiring board 2, and the opening 62 is formed on the wiring board 2. Opposite to the back surface side, all the ink introduction communication ports 22 are positioned in the openings 62 and are bonded using an adhesive. Reference numeral 62 denotes an introduction port for introducing ink into the ink manifold 6.

  The ink manifold 6 supplies the internal ink in common to the channels 12 of all the head chips 1 arranged on the wiring board 2 through the ink introduction communication ports 22. For this reason, it suffices to supply ink only to this one ink manifold 6 to the inkjet head H in which a plurality of head chips 1 are arranged, and only to connect an ink supply pipe (not shown) to the introduction port 62. This completes the piping work for ink supply. Therefore, piping work and piping structure can be greatly simplified.

FPC
The FPCs 7A and 7B are preliminarily patterned with the same number and the same pitch as the wiring electrodes 23 formed on the surface of the wiring board 2 on one surface, and at the outer end portions 21A and 21B of the wiring board 2, Each wiring electrode 23 and each wiring 71 are positioned and joined so as to be electrically connected to each other.

  In the figure, a plurality of wires are collectively indicated by reference numeral 71.

  In the present invention, a plurality of head chips 1 are arranged on the surface of one wiring board 2, and wiring electrodes 23 for applying a driving voltage to each head chip 1 are all arranged on the same surface of the wiring board 2. Therefore, electrical connection with each wiring 71 of the FPCs 7A and 7B with respect to each of the wiring electrodes 23 can be performed only on the surface of the wiring board 2. For this reason, since the connection work of FPC7A, 7B can be performed only from the surface side, it can be simplified extremely.

  In this embodiment, on the surface of the wiring board 2, the wiring electrodes 23 are distributed and drawn on both sides of the plurality of head chips 1 arranged in a staggered manner, and one FPC 7A and one FPC 7B, respectively. Is connected. That is, in the present invention, since the FPC can be connected only on the surface of the wiring board 2, it is common to the wiring electrodes 23 of all the head chips 1 arranged on the outer end portion 21A or 21B of the wiring board 2. It is possible to connect with one FPC.

  Further, in the present invention, although not shown, for example, the wiring electrodes 23 of two head chips 1 adjacent to each other at the same outer end portion 21A or 21B of the wiring substrate 2 of the six head chips 1 arranged on the wiring substrate 2 are arranged. A single FPC can be connected together, and a flexible FPC connection configuration can be adopted.

  Of course, the wiring electrodes 23 of the plurality of head chips 1 may be connected using individual FPCs for each head chip 1. Even in this case, as described above, since the connection work with the FPC can be performed only on the surface of the wiring board 2, the workability is remarkably excellent as compared with the conventional case.

As shown in FIG. 6, on the surface of the wiring board 2, each ink introduction communication port 22 corresponds to each of the ink introduction communication ports 22 on the outer side of the end portion in the length direction (X direction). A positioning mark 4 for positioning the head chip 1 is formed. The mutual positions of the positioning marks 4 are precisely defined. By positioning the head chip 1 according to the positioning marks 4, the mutual positions of the head chips 1 can be accurately defined.

  Each positioning mark 4 is patterned by the same metal material as the wiring electrode 23 by the sputtering method, the vapor deposition method, or the like in the same process as the formation of the wiring electrode 23. Therefore, it is possible to form a pattern with high accuracy using the normal patterning technique and the position of each line and the dimension of each straight line constituting the positioning mark 4.

  One positioning mark 4 may be provided outside one of the end portions corresponding to one communication port 22 for ink introduction, that is, corresponding to one head chip 1. The linearity of each head chip 1 in the channel row direction can be maintained, which is particularly preferable in the case of a full line type ink jet head as in this embodiment.

  FIG. 7 shows details of one positioning mark 4.

  The positioning mark 4 has two parallel frame portions 41 and 42 having a predetermined width parallel to each other. The distance between the inner edges 41a and 42a of the parallel frame portions 41 and 42 is set to be equal to the distance between the upper surface 1c and the lower surface 1d of the head chip 1, and the rear surface of the head chip 1 in the meantime. The positioning is performed so that the outer edge in contact with the upper surface 1c of 1b and the outer edge in contact with the lower surface 1d are accommodated in parallel.

  Note that the lower parallel frame portion 42 in the drawing is divided into two straight portions 421 and 422, but these straight portions 421 and 422 are arranged in the same straight line, and one parallel frame portion. It can be regarded as part 42.

  An end portion positioning straight line 43 orthogonal to the parallel frame line portions 41, 42 is provided between the parallel frame line portions 41, 42 at the end portion of the positioning mark 4 far from the ink introduction communication port 22. doing. This end positioning straight line 43 is used for positioning the outer edge where the rear surface 1b of the head chip 1 is in contact with the end surface 1e (FIG. 2) in the channel row direction. Here, the width is the same as that of the parallel frame portions 41 and 42. The plurality of rectangular portions 43a and 43b are arranged in a staggered manner across the parallel frame portions 41 and 42, thereby forming a boundary between the rows of the rectangular portions 43a and the rows of the rectangular portions 43b. Yes. The end portion positioning straight line 43 may be formed as a gap having a predetermined width by providing a predetermined gap between the boundaries of the rows of the rectangular portions 43a and the rows of the rectangular portions 43b.

  One parallel frame portion 42 has two position confirmation linear portions 44, 45 formed at the same position as the parallel frame line portions 41, 42 at positions determined from the end portions of the parallel frame line portion 42. have. Each position confirmation straight line portion 44, 45 is formed to be orthogonal to the parallel frame portion 42. Therefore, the head chip 1 that is properly bonded extends in the direction (Y direction) orthogonal to the arrangement direction of the channels 12.

  A gap having a predetermined width is formed between the straight line portions 44 and 45 for position confirmation. The straight line portion 421 of the parallel frame line portion 42 is connected at right angles to the straight line portion 44 for position confirmation, and the straight line portion 422 is connected to the other side. Are connected at right angles to the straight line portion 45 for position confirmation.

  The outer edges 44a and 45a of the position confirmation linear portions 44 and 45 are linear and parallel to each other. The distance between the outer edges 44 a and 45 a is formed to be equal to the distance between the inner wall surfaces 151 and 151 of the position confirmation groove 15 formed in the head chip 1. These outer edges 44a and 45a constitute a first linear pattern, and the inner edge part 42a of the parallel frame line part 42 in contact with the outer edges 44a and 45a at a right angle constitutes a second linear pattern.

  The first linear pattern only needs to have two outer edges 44a and 45a that are parallel to each other, and is not limited to the one formed by the two linear portions 44 and 45 for position confirmation. May be formed by both outer edges of the two, but those formed by two position confirmation linear portions 44 and 45 as in the present embodiment are preferred.

  Reference numeral 46 denotes a linear portion for holding the adhesive, which functions to hold the adhesive applied between the rear surface 1b of the head chip 1 and the surface of the wiring board 2 and prevent the outflow to the surroundings.

<Head chip manufacturing method>
Here, an example of a method for manufacturing the head chip 1 will be described with reference to FIGS.

  First, a piezoelectric element substrate 101 made of polarized PZT or the like is bonded onto one substrate 100 using an epoxy adhesive, and a dry film 102 is attached to the surface of the piezoelectric element substrate 101. (FIG. 8 (a)).

  Next, a plurality of parallel grooves 103 are ground from the dry film 102 side using a dicing blade or the like. Each groove 103 extends from one end of the piezoelectric element substrate 101 to the other end and is ground at a constant depth almost reaching the substrate 100 so that the size and shape of the groove 103 are almost the same in the length direction. (FIG. 8B).

  Next, a metal material such as Ni, Co, Cu, or Al is applied by sputtering, vapor deposition, or the like from the side on which the groove 103 is ground, and a metal film is formed on the upper surface of the dry film 102 and the inner surface of each groove 103 left uncut. 104 is formed (FIG. 8C).

  Thereafter, the dry film 102 is removed together with the metal film 104 formed on the surface thereof, whereby the substrate 105 having the metal film 104 formed only on the inner surface of each groove 103 is obtained. Then, two similarly formed substrates 105 are prepared, aligned so that the grooves 103 of each substrate 105 match each other, and bonded using an epoxy adhesive or the like (FIG. 8D). . Channels 12 are formed by the joined grooves 103, and a partition between the channels 12 serves as a drive wall 13.

  In addition to this, although not shown, two piezoelectric element substrates with different polarization directions are bonded together, a liquid resist is applied with a spin coater, exposed and developed, and a groove to be a channel is diced, A substrate similar to the above can also be produced by forming a drive electrode by plating or the like and attaching a cover substrate so as to cover the groove.

  Next, two identical substrates obtained in this way are prepared, and are superposed and bonded so that the pitch of the channels 12 is shifted by a half pitch to form one wafer 106. From the upper surface, dicing is performed. Using the saw DS, the position confirmation groove 15 is linearly ground so as to be parallel to the length direction of the channel 12 (FIG. 9A).

  The dicing saw DS performs groove grinding by rotation. Further, since the dicing saw DS and the wafer 106 can be relatively moved with high precision by mechanical precision, the inner wall surface 151 of the position confirmation groove 15 facing the dicing saw DS. , 151 can be formed so as to be parallel to each other with high accuracy, to be orthogonal to the upper surface 1c of the head chip 1 with high accuracy, and to have a constant depth over the entire length of the groove.

  Thereafter, the wafer 106 is cut along a direction orthogonal to the length direction of the channel 12 to produce a plurality of harmonica type head chips 1 having two channel rows at a time. The width between the cut lines C, C... Determines the drive length (L length) of the channels 12 of the head chips 1, 1... Produced thereby, and is appropriately determined according to this drive length ( FIG. 9B).

  Next, a connection electrode 14 is formed on the rear surface of the head chip 1 cut out from the wafer 106 by selectively applying a metal material by a sputtering method, a vapor deposition method, or the like. As shown in FIG. The head chip 1 having the connection electrode 14 is produced.

<Head chip positioning method>
Next, a method for manufacturing the full-line type inkjet head H by positioning and bonding each head chip 1 to the surface of the wiring board 2 will be described.

  Each head chip 1 is positioned on the surface of the wiring board 2 and then bonded by an epoxy adhesive applied between the rear surface 1b and the surface of the wiring board 2 by applying pressure and heating as necessary. The Each head chip 1 has a surface on the surface of the wiring substrate 2 so that the position confirmation linear portions 44 and 45 of the positioning marks 4 formed on the surface of the wiring substrate 2 can be seen in the position confirmation grooves 15 formed on the upper surface 1c. Temporarily placed. At the time of this temporary placement, by confirming the two parallel frame portions 41 and 42 of the positioning mark 4 and the end portion positioning straight line 43, the position confirmation straight portions 44 and 45 are generally in the position confirmation groove 15. It is easy to place the head chip 1 so that can be seen.

  The position confirmation of the head chip 1 is performed by using an image recognition apparatus using a CCD or the like so as to enlarge and look down the position confirmation groove 15 from the front surface 1a side of the head chip 1.

  FIG. 10 shows the state of the positional relationship between the head chip 1 and the positioning mark 4 that has not been positioned at an appropriate position and angle immediately after temporary placement, as viewed from the front surface 1 a side of the head chip 1.

  In this state, the opposed inner wall surfaces 151 and 151 of the position confirmation groove 15 of the head chip 1 and the outer edges 44a and 45a of the position confirmation linear portions 44 and 45 do not coincide with each other in parallel. There is an angle shift. At this time, the positions of the upper surface 1c and the lower surface 1d of the head chip 1 to be image-recognized do not coincide with the inner edges 41a and 42a of the parallel frame portions 41 and 42, respectively, and the end surface of the head chip 1 It can be seen that the position 1e does not coincide with the end positioning straight line 43 in parallel.

  Therefore, while confirming the image recognition device, as shown in FIG. 11, the inner wall surfaces 151, 151 facing each other and the outer edges 44 a, 45 a of the position confirmation linear portions 44, 45 are located in the position confirmation groove 15. The position of the head chip 1 is adjusted so as to match. Similarly, all the head chips 1 are adjusted to predetermined positions on one wiring board 2.

  In this way, the inner wall surfaces 151, 151 of the position confirmation groove 15 of each head chip 1 and the outer edges 44a, 45a of the position confirmation linear portions 44, 45 of the positioning mark 4 of the wiring board 2 are mutually connected. By making them coincide with each other in parallel, the parallelism between all the head chips 1 on the wiring board 2 is ensured, and the position in the direction along the channel row direction (X direction) is accurately defined and adjacent. A proper separation distance between the head chips 1 is ensured.

  Such positioning is performed by confirming the two inner wall surfaces 151 and 151 of the position confirmation groove 15 formed on one side surface of the head chip 1, so that the parallelism of the two surfaces is reduced in a small field of view. Confirmation can be performed at the same time, so that easy and accurate positioning confirmation can be performed. In addition, the inner wall surfaces 151 and 151 of the position confirmation groove 15 can be processed with high accuracy by the dicing saw DS as compared with the cutting processing of the outer end surface of the head chip 1, so that more accurate positioning can be performed. .

  Thereby, each connection electrode 14 formed on the rear surface 1b of the head chip 1 and each wiring electrode 23 formed on the surface of the wiring board 2 can be accurately aligned one-to-one, and the inkjet head H The entire nozzle pitch can be made uniform, and there is no possibility of causing image unevenness due to pitch unevenness.

  Further, when the position of the head chip 1 is adjusted, since the periphery of the position confirmation groove 15 is enlarged and recognized, the inner edge 42a of the parallel frame portion 42 of the positioning mark 4 that is recognized simultaneously is used, By adjusting the position of the head chip 1 so that the inner edge 42a appears to coincide with the position of the upper surface 1c of the head chip 1, positioning in the direction (Y direction) orthogonal to the channel row direction of each head chip 1 is performed. It can be carried out.

  After each head chip 1 is positioned as described above, the adhesive is cured by applying pressure to the wiring board 2 and heating as necessary, and then a spacer member separately formed between the head chips 1. 5 are bonded using an adhesive. By joining the spacer members 5, the front surface 1 a of each head chip 1 is connected to the surface of the spacer member 5 in the same plane, and a rectangular nozzle plate adhering surface having a wide flat surface is formed.

  The nozzle plate 3 is formed in a size corresponding to the nozzle plate attaching surface formed by joining the spacer members 5, and is previously processed by laser processing so as to correspond to the channel 12 of each head chip 1. A nozzle hole 31 is formed. The nozzle plate 3 in which the nozzle holes 31 are formed is attached to the nozzle plate attaching surface using an adhesive, thereby covering the front surface 1a of each head chip 1, and each nozzle hole 31 is connected to each channel 12 By communicating with the inside, the ink in the channel 12 can be ejected from the nozzle hole 31.

  Thereafter, the ink manifold 6 is positioned and bonded to the back side of the wiring board 2, and the FPCs 7 </ b> A and 7 </ b> B are positioned and bonded to the outer end portions 21 </ b> A and 21 </ b> B on the surface of the wiring board 2.

<Other arrangements of head chips>
As shown in FIG. 9, when the head chip 1 is formed by being cut out from one wafer 106, the length of the inkjet head H when arranging a plurality of the head chips 1 on the surface of one wiring substrate 2. The head chips 1, 1 adjacent in the vertical direction are preferably head chips 1, 1 cut from different wafers 106.

  It is known that the characteristics of the head chip 1 cut out from the same wafer 106 show a similar tendency. For this reason, in the inkjet head formed by arranging the head chips 1 cut out from the same wafer 106 adjacent to the surface of the same wiring board 2, the stripe unevenness of the low spatial frequency image that is easily recognized by human eyes. Will occur, degrading the image quality.

  FIG. 12 shows the velocity distribution of ink droplets ejected from each nozzle of a 768-nozzle line-type inkjet head configured by adjoining head chips A1, A2, and A3 cut out from the same wafer. The horizontal axis indicates the number of nozzles, and the vertical axis indicates the ink droplet ejection speed (m / s).

  As described above, when the head chips A1, A2, and A3 cut out from the same wafer are made adjacent to each other, in the same nozzles of the head chips A1, A2, and A3, for example, as in the nozzle region a shown in the drawing, the same is true. A region with a smooth velocity distribution appears. When an image is recorded by an ink jet head having such a nozzle area a, streaks of an image having a low spatial frequency that are easily recognized by human eyes become uneven, which causes a significant decrease in image quality. In the case of such image streak unevenness, when an image is recorded by scanning the ink jet head along the main scanning direction, it is possible to prevent deterioration in image quality by complementing with different nozzles by a method such as thinning-out. Although it is possible, in the case of a line-type inkjet head H provided in a fixed manner in the printer, such a method cannot be adopted, and image unevenness appears remarkably.

  On the other hand, FIG. 13 shows the velocity distribution of ink droplets ejected from each nozzle of a 768-nozzle inkjet head constructed in the same manner as described above with head chips B1, B2, and B3 cut out from different wafers adjacent to each other. Yes.

  Thus, when the head chips B1, B2, and B3 cut out from different wafers are adjacent to each other, the nozzle area a having the same speed distribution as shown in FIG. 12 does not appear, and the speed varies moderately. I understand that. As a result, it is possible to reduce streak unevenness in the low spatial frequency image that is easily recognized by human eyes appearing in the output image, and each head chip 1 so that the nozzle pitch of the entire inkjet head H is uniform as described above. In combination with the fact that the image can be positioned at an appropriate position, a higher quality output image can be obtained.

  The plurality of head chips 1 are not limited to those arranged in a zigzag pattern on the surface of the wiring board 2 but can be arranged in various ways.

  The present invention is not limited to the case of configuring a line head, but can be similarly applied to the case of configuring a multi-nozzle inkjet head using a plurality of head chips 1.

The perspective view which shows an example of the multichip inkjet head concerning this invention Partial perspective view of one head chip as seen from the rear side Sectional drawing which follows the (iii)-(iii) line | wire in FIG. Sectional view along line (iv)-(iv) in FIG. Partial enlarged view of position confirmation groove Partial plan view of the surface of the wiring board before bonding the head chip Enlarged view showing details of one positioning mark (A)-(d) is a figure explaining an example of the manufacturing method of a head chip. (A) is a perspective view showing a state in which a position confirmation groove is formed in one wafer, (b) is a perspective view showing a state in which a plurality of head chips are cut out from one wafer. A view of the positional relationship between a positioning mark and a head chip that has not been positioned at an appropriate position and angle immediately after temporary placement, as viewed from the front side of the head chip. A view of the positional relationship between the head chip and the positioning mark when the head chip is positioned at an appropriate position and angle from the front side of the head chip. A graph showing the velocity distribution of ink droplets ejected from each nozzle of an inkjet head formed by adjoining head chips cut out from the same wafer A graph showing the velocity distribution of ink droplets ejected from each nozzle of an ink jet head configured by adjoining head chips cut from different wafers

Explanation of symbols

1: Head chip 1a: Front surface 1b: Rear surface 1c: Upper surface 1d: Lower surface 1e: End surface 11: Drive wall 12: Ink channel 121: Front side opening 122: Rear side opening 13: Driving electrode 14: Connection electrode 15 Position confirmation groove 151: Inner wall surface 2: Wiring substrate 21A, 21B: Outer end portion 22: Inlet port for communication 23: Wiring electrode 3: Nozzle plate 31: Nozzle 4: Positioning mark 41, 42: Parallel frame portion 41a : Inner edge 42a: Inner edge (second linear pattern)
421, 422: linear portion 43: straight line for positioning the end portion 43a, 43b: rectangular portion 44, 45: linear portion for position confirmation 44a, 45a: outer edge portion (first linear pattern)
46: Straight portion for holding adhesive 5: Spacer member 6: Ink manifold 61: Opening 62: Inlet 7A, 7B: FPC
71: Wiring

Claims (11)

Drive walls and channels made of piezoelectric elements are alternately arranged side by side, outlets and inlets of the channels are arranged on the front and rear surfaces, respectively, drive electrodes are formed on the drive walls, and the drive electrodes are electrically connected to the rear surface. A multi-chip inkjet head that has a plurality of head chips formed with connection electrodes to be connected to and discharges ink in the channel from nozzles by applying a driving voltage to the driving electrodes,
A plurality of the head chips are formed on a single wiring substrate having wiring electrodes corresponding to the connection electrodes of the head chips formed on the surface and an ink introduction communication port corresponding to the head chip being opened. The connection electrode and the wiring electrode are electrically connected, and the channel inlet of the head chip is positioned and bonded so as to face the communication port for introducing the ink; and
A single nozzle plate having a nozzle hole formed at a position corresponding to the channel of all the head chips is attached to the front surface of all the head chips,
One ink manifold for supplying ink in common to all the head chips through the ink introduction communication port is joined to the back surface side of the wiring board ,
The multi-chip inkjet head , wherein the plurality of head chips are arranged such that head chips cut out from different wafers are adjacent to each other . Drive walls and channels made of piezoelectric elements are alternately arranged side by side, outlets and inlets of the channels are arranged on the front and rear surfaces, respectively, drive electrodes are formed on the drive walls, and the drive electrodes are electrically connected to the rear surface. A multi-chip inkjet head that has a plurality of head chips formed with connection electrodes to be connected to and discharges ink in the channel from nozzles by applying a driving voltage to the driving electrodes,
A plurality of the head chips are formed on a single wiring substrate having wiring electrodes corresponding to the connection electrodes of the head chips formed on the surface and an ink introduction communication port corresponding to the head chip being opened. The connection electrode and the wiring electrode are electrically connected, and the channel inlet of the head chip is positioned and bonded so as to face the communication port for introducing the ink; and
A single nozzle plate having a nozzle hole formed at a position corresponding to the channel of all the head chips is attached to the front surface of all the head chips,
One ink manifold for supplying ink in common to all the head chips through the ink introduction communication port is joined to the back surface side of the wiring board ,
A spacer member having a height from the surface of the wiring board equal to the height of the front surface of the head chip is provided between the plurality of head chips, and one nozzle plate is connected to the front surfaces of all the head chips. A multi-chip ink-jet head, wherein the multi-chip ink-jet head is adhered to the surface of the spacer member . The multi-chip inkjet head according to claim 2 , wherein the plurality of head chips are arranged so that head chips cut out from different wafers are adjacent to each other. The wiring electrode is formed from the ink introduction port corresponding to the connection electrode of the head chip to the outer end portion of the wiring substrate, and is driven to the wiring electrode at the outer end portion of the surface of the wiring substrate. 4. The multi-chip inkjet head according to claim 1, 2 or 3, wherein an FPC in which wiring for transmitting a driving voltage from the IC is formed is electrically connected. A line-type inkjet head is arranged by arranging a plurality of the head chips on the surface of the wiring board so that the pitch of the channels is equal to the pitch of the adjacent head chips along the channel arrangement direction. The multichip ink jet head according to claim 1, wherein the multichip ink jet head is formed.   The positioning mark corresponding to each of the plurality of head chips is formed at a predetermined position on the surface of the wiring board, and each of the plurality of head chips is positioned by the positioning mark. The multichip inkjet head in any one of 1-5. The positioning mark has a first linear pattern that extends in a direction orthogonal to the channel arrangement direction of the head chip and whose outer edges are parallel to each other.
The width of the first linear pattern is the same as the width of the first linear pattern across the front surface and the rear surface of the head chip at a position corresponding to the first linear pattern on the side surface in contact with the rear surface of the head chip, and , Straight grooves with parallel inner wall surfaces are processed,
When viewed from the front side of the head chip bonded to the surface of the wiring substrate, the inner wall surfaces facing each other in the groove appear to coincide with both outer edges of the first linear pattern. The multi-chip inkjet head according to claim 6, wherein each of the plurality of head chips is positioned.   8. The multi-chip inkjet head according to claim 7, wherein the first linear pattern is composed of two parallel linear patterns with a predetermined interval.   9. The multi-chip inkjet head according to claim 7, wherein the first linear pattern is formed in a predetermined position on the surface of the wiring board using the same metal material as the wiring electrode. . A second straight line having a linear portion perpendicular to the first linear pattern, which is a pattern for positioning a side surface parallel to the channel arrangement direction of the head chip at a predetermined position on the surface of the wiring board. A pattern is formed,
Positioned so that the outer edge of the rear surface of the head chip is seen to coincide with the linear portion of the second linear pattern when viewed from the front surface side of the head chip bonded to the surface of the wiring board. The multi-chip inkjet head according to claim 7, 8 or 9.   11. The multi-chip inkjet head according to claim 10, wherein the second linear pattern is formed in a predetermined position on the surface of the wiring board using the same metal material as the wiring electrode.

Images