JP3185366B2 - Inkjet head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand ink jet head which, when print data is received, causes ink droplets to fly to form dots on recording paper using the ink droplets.

[0002]

2. Description of the Related Art As described in Japanese Patent Publication No. 2-52625, an on-demand type ink-jet head deforms a part of a wall of a container forming an ink chamber by a piezoelectric element, and generates ink droplets from nozzles by pressure generated. To form dots on the recording paper.

In the above-described on-demand type ink jet head, a projection is used for joining the pressure generating member and the elastic plate, and the projection is pushed into the elastic plate in order to efficiently transmit the displacement of the pressure generating member to the elastic plate. And the projection and the elastic plate were brought into close contact with each other. However, as a result, large deformation has occurred in the elastic plate, the internal stress has increased, and there has been a problem that the elastic plate is broken, deformed, or cracked. That is, as shown in FIG. 19, the projections 220 and 221 and the pressure generating members 150 and 151 usually have a positional variation at the time of manufacturing, and the end faces 270 and 2 of the projections 220 and 221 are formed.
71, a displacement e1 occurs at the end surfaces 280, 281 of the pressure generating members 150, 151, and a displacement e2 occurs at the end surfaces 280, 281 of the pressure generating members 150, 151. Conventionally, when joining is performed in such a state, as shown in FIG. 20, the end surface 281 of the pressure generating member 151 at a long distance.
Was applied to the end surface 271 of the projection 221, a compressive stress was applied between the projection 221 and the pressure generating member 151, and the elastic plate 30 had to be deformed by pushing in only e <b> 3 for the purpose of adhesion. For this reason, the most deformable protrusion 220
In this case, the pressing amount e1 + e2 + e3 is also pressed, so that the deformation of the elastic plate 30 and the internal stress become extremely large. In such a situation, the elastic plate 30 may be broken, which causes ink leakage. As a result, it has been a major cause of a catastrophic failure such as an electric short circuit of the pressure generating member and corrosion of the constituent members.

Conventionally, in order to solve this problem, a change to an elastic plate material that can withstand high strain and high stress has been made. However, such a material is very difficult to use because it is expensive. Was something.

[0005] Further, since such an ink jet head is required to have high precision and clear printing, it is necessary to arrange components constituting each part with high precision and a uniform pitch.
In order to compress the ink particularly efficiently and without variation,
Large deviations and errors are not allowed in the positional relationship between the projection and the pressure generating member. For this reason, in the above-described ink jet head, by providing a guide component, the pressure generating members are arranged at an equal pitch, and the positional accuracy with respect to the protrusion is ensured. However, such guide parts require accuracy, and
Since the number of parts in the entire head also increases, cost increases and man-hours for assembly have increased. As described above, the price paid for ensuring the positional accuracy between the pressure generating member and the protrusion is large.

[0006]

The problem to be solved is that the elastic plate must be deformed more than the deformation for ink discharge in order to bring the pressure generating member into close contact with the elastic plate. . In addition, a guide component must be prepared in order to accurately arrange the pressure generating member.

[0007]

SUMMARY OF THE INVENTION The present invention provides a nozzle, an ink chamber connected to each of the nozzles , an elastic plate having a projection forming one wall of the ink chamber, and a leg. a pressure generating member which is joined, via said foot by pressure generating member is displaced to the elastic plate, increases the ink pressure in the ink chamber, the ink jet head for discharging ink droplets from the nozzle, the said leg Elastic plate
Protrusions are characterized by being adsorbed by a magnetic force.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of an ink jet head according to the present invention. In this drawing, the overall configuration of the ink jet head of the present invention and its mechanism will be described. For explanation, a part is cut and a cross section is shown. The plurality of pressure generating members 150 are arranged at an equal pitch on one surface of the substrate 14,
A leg 250 is joined to the tip. In this embodiment, a guide part for mechanically supporting the position of the pressure generating member 150 is not used. The leg 250, the pressure generating member 150, and the entire substrate 14
Is fixed to the case 37 so as to be joined one-to-one to the protruding portion 220 formed on the case 37. The protrusion 220 is formed on the elastic plate 30 so that it can be arranged at the center of the ink chamber 170. Nozzle forming substrate 3 for discharging ink
In No. 3, the nozzle 190 is machined. The ink ejection mechanism of this ink jet head will now be described. The displacement generated in the pressure generating member 150 is caused by the elastic plate 3 using the leg 250 as a medium.
The 0 projection 220 is pressed. By this action, the elastic plate 30 bends toward the ink chamber 170, and the ink chamber 17
The ink in 0 is pressurized. As a result, ink droplets are ejected from the nozzle 190.

FIG. 2 is an enlarged view of the elastic plate 30 and the leg 250 according to the first embodiment of the present invention. This figure shows a state immediately before the elastic plate 30 and the leg 250 are joined in order to explain the effect of this embodiment. According to the gist of the present invention, the elastic plate 3
0 is a ferromagnetic material, and the legs 250 and 251 are made of a paramagnetic material. Protrusions 220 and 22 in contact with legs 250 and 251
1 has a magnetic north pole and a south pole. Legs 250, 2
An adhesive 90 such as an epoxy-based adhesive is applied to end surfaces 260 and 261 of the projection 51 to join the projections 220 and 221. Here, the projections 220, 221 and the legs 250, 25
This embodiment will be described focusing on the step of bonding the first and second substrates. For joining, when the two are gradually brought closer together, the protrusion 22
The force of attracting the legs 250 and 251 is generated by the magnetic force of 0 and 221. In general, it is difficult to process and arrange the pressure generating member 150 with high accuracy.
0, a position shift e like the leg 250 and the projection 220 often occurs. Conventionally, when the projection 220 and the leg 250 are joined while leaving such a displacement e, there is a problem that the joining area becomes extremely small, and the displacement generated by the pressure generating member 150 is not sufficiently transmitted to the projection 220. As a result, the ink ejection characteristics sometimes deteriorated. However, in the present embodiment, since the leg 250 is attracted to the protrusion 220 and the correcting force of the arrow 60 acts on the leg 250, the positional displacement e of the pressure generating member 150 is corrected as shown in FIG. It is joined to the elastic plate 30 in the formed shape. Therefore, there is an advantage that the joint area between the leg 250 and the projection 220 is sufficiently secured. In addition, since guide parts for positioning the leg 250 and the pressure generating member 150 are not required, the number of inkjet head parts is reduced, friction and wear between the guide part and the pressure generating member 150 are avoided, and the leg due to temperature deformation is reduced. An advantage such as prevention of misalignment between the protrusion 250 and the projection 220 is obtained.

FIG. 4 shows a second embodiment of the present invention. In this embodiment, the legs 250 are magnetized separately in the y direction from the north pole and the south pole, and the direction of magnetization is different from that in the previous embodiment. Also, the bonding is realized only by magnetic attraction without using an adhesive.

Usually, the pressure generating member 150 is processed by cutting the piezoelectric element with a dicer or the like, and is arranged at an equal pitch.
However, the pressure generating member 1 may be disturbed due to variations in cutting conditions.
As shown by the pitch P1, the pitch often narrows as shown by the pitch P1. When the pressure generating member 150 is bonded to the elastic plate 30 while keeping the inclination, the positional relationship between the leg 250 and the projection 220 is shifted in the x direction, so that the contact area between the leg 250 and the projection 220 is reduced. The displacement of the pressure generating member 150 is reduced
As described in the first embodiment, a problem that cannot be sufficiently transmitted occurs. However, in this embodiment, the leg 2
Since the magnet 50 is magnetized, the north pole and the south pole of the adjacent legs 250 and 251 repel each other as shown in FIG. The repulsive force corrects the inclination of the pressure generating member 150 and produces an effect that the position of the leg 250 is corrected like the pitch P2. Also, as shown in FIG.
Although the inclination of the pressure generating member 150 may not be corrected only by the repulsive force of 0 or 251, the present invention is effective in such a case. The principle is the same as that described with reference to FIG. 2, but the state is shown in FIG. 7 again. In this embodiment, since the elastic plate 30 is made of a paramagnetic material, the leg 250 made of a ferromagnetic material is attracted to the protrusion 220. Therefore, even when the pressure generating member 150 is inclined as shown by the broken line, the pressure generating member 150 is corrected in the direction of the arrow 60 by the suction force, and is joined to the projection 220 at the correct position.

In general, in order to provide an ink jet head at a small size and at a low cost, it is necessary to increase the density of the nozzle arrangement. Therefore, the pressure generating member 150 and the protrusion 2
20 becomes very narrow, but as a result, even if the pitch of the pressure generating members 150 is slightly shifted, they come into contact with each other and interfere with each other, and the displacement characteristics change.
Alternatively, the leg 250 and the protrusion 220
The displacement of the pressure generating member 150 is not sufficiently transmitted to the protrusion 220 and the ink is not ejected, or the characteristics are poor even if the ink is ejected, since the displacement of the pressure generating member 150 is not sufficiently transmitted to the projection 220 due to the displacement of the contact area. Was.

However, as described above, in the present embodiment, the pitch of the pressure generating member 150 is maintained by the repulsive force of the leg 250 and the inclination is corrected, so that there is no contact. Further, since the leg 250 is attracted to the protrusion 220 and the position is further corrected, a contact area between the two is ensured. Therefore, the displacement of the pressure generating member 150 can be sufficiently transmitted. These effects make it possible to provide an ink jet head having stable ink ejection characteristics.

In the present embodiment, the deformation of the elastic plate 30 in the y direction can be reduced, and the elastic plate 30 can be prevented from breaking. FIG. 8 shows the legs 150 and 151 and the protrusions 22 according to the embodiment of the present invention.
FIG. As shown here, the projections 220 and 221 and the legs 250 and 251 have positional variations at the time of manufacturing, and the end faces 270 and 27 of the projections 220 and 221.
FIG. 1 shows a state in which the positional deviation of the pressure generating members 150 and 151 is e1 and the positional deviation of the end surfaces 280 and 281 of the pressure generating members 150 and 151 is e2.
This is the same state as the conventional shift amount shown in FIG. When bonding is performed in such a state, in this embodiment, the protrusion 22
Attraction force due to magnetic force acts between 0, 221 and the legs 250, 251 so that the end surface 261 of the leg 251 and the end surface 271 of the protrusion 221 come into close contact with each other. Therefore, there is no need to push the legs 250 and 251 for close contact. Therefore, as shown in FIG. 9, even with the most deformable protrusion 220, the pushing amount is only e1 + e2, and the deformation amount e1 + e of the prior art.
2 + e3 can be reduced by the pushing amount e3 for close contact. As a result, deformation and internal stress of the elastic plate 30 can be suppressed, and irreparable damage such as breakage can be prevented. Further, the position variation e1 of the projections 220 and 221 and the position variation e2 of the legs 250 and 251.
Can be widened to facilitate component manufacturing.

As described above, generally, in the ink jet head of the present invention, as shown in FIG. 10, the projections 220 of the elastic plate 30 and the legs 250 at the tip of the pressure generating member 150 generally have undulations. Positional variations such as surface roughness occur. Considering the manufacturing and ink ejection characteristics, one problem is to absorb the positional variation on the one hand, and on the other hand the end face 270 of the projection 220 and the leg 250
Conventionally, it has been pointed out that the end surfaces 260 must be uniformly joined. In this regard, in this embodiment, it is possible to join as shown in FIG. 11, and while absorbing the variation by magnetic attraction as described above,
A state in which an appropriate bonding force is applied between the end faces is realized. Also,
It is also possible to suppress deformation and stress in the elastic plate 30 at the same time.

In the present invention, the arrangement of the magnetic poles in the leg 250 can be further devised. 12, 13, 14, 15
The embodiment will be described with reference to FIG.

FIG. 12 shows such a third embodiment.
In this embodiment, the leg 250 is magnetized separately from the N pole and the S pole in the z direction, that is, the thickness direction of the leg 250. In this way, in the state where the elastic plate 30 and the leg 250 are joined, the magnetic force lines pass through the elastic plate 30 and close as a magnetic force line circuit, so that the attraction force between the elastic plate 30 and the leg 250 becomes larger than in the previous embodiment. . This is shown in FIG. The purpose of this embodiment is to increase the attraction force, and the leg 250 is strongly attracted to the projection 220 and the leg 2
There are fifty positions that are precisely located. Also, z
There are other advantages of arranging the magnetic poles in the direction, that is, the thickness direction of the legs 250. That is, the distance between the north pole and the south pole can be increased, and the density of the magnetic flux generated by the legs 250 can be increased. This secures the pitch of the leg 250 and the protrusion 22
This is a further advantage in ensuring the positional relationship between the legs 250 and 0, because the magnetic repulsion between the legs 250 and the attraction between the protrusions 220 and the legs 250 are increased.

FIG. 14 shows a fourth embodiment of the present invention. One of the features of the present embodiment is that both the protrusion 220 and the leg 250 are made of a paramagnetic material to arrange the magnetic poles.
Is that the arrangement of the magnetic poles is such that the N pole and the S pole face each other in the projection 220 and the leg 250. The advantage of this embodiment is that the centripetal force of the leg 250 on the protrusion 220 (arrow 60) is obtained by facing the magnetic pole arrangement of the protrusion 220 and the leg 250.
Is to be able to be increased. That is, in the state shown in FIG.
While being repelled by the N pole of the 20, it is attracted to the S pole,
The poles are attracted to the N pole of the projection 220, and a centripetal force (arrow 60) is generated so that the center of the leg 250 tries to coincide with the center of the projection 220. As a result, as shown in FIG.
This means that the bonded state in which the centers of the 20 are almost completely matched can be realized.

In the present invention, the shape of the leg 250 can be further devised. 16 and 17 show a fifth embodiment of the present invention. This embodiment is characterized by the shape of the leg 250,
The length of the leg 250 is longer than in the first to fourth embodiments. There are two advantages of such a configuration. The first advantage is that the distance L1 between the magnetic poles in the leg 250 as shown in FIG.
The magnetic flux density is increased because
This is the point that the adsorbing force increases. Further, the second advantage is that the ink can be sufficiently compressed because L1 becomes longer and the area for displacing the projection 220 becomes larger.

As described above, by using only magnetic attraction for the joining force between the elastic plate 30 and the legs 250 as in the second to fifth embodiments, reversibility can be provided for the joining. . By applying this, it is possible to make the head separable. If the ink jet head is separable, it is possible to save the trouble of replacing parts of the entire ink jet head and maintain the reliability. FIG. 18 shows the overall configuration of such a head.
Shown in The cavity 45 includes the elastic plate 30, the ink chamber forming substrate 230, and the nozzle forming substrate 33. The driving section 46 includes a pressure generating member 150, legs 250, the substrate 14 for supporting the legs 250, and a case 37 for fixing the substrate 14. The projection 45 and the hole 48
The legs 250 and the projections 220 are supported in a positional relationship with each other.
It is performed by attracting by the magnetic force. Since the suction is performed by magnetic force, the cavity 45 and the driving unit 46 have a detachable configuration. In particular, as shown in the third, fourth, and fifth embodiments, when the attraction force between the projection 220 and the leg 250 is large or when the centripetal force is large, it is advantageous in terms of absorbing positional variations and stabilizing the bonding strength. It is.

[0022]

As described above, in the ink jet head of the present invention, since the legs are attracted to the projections by the magnetic force and the correcting force is applied, the elastic plate is corrected in a form in which the displacement of the pressure generating member is corrected. Will be joined at the correct position. Therefore, there is an effect that the joint area between the leg and the projection is sufficiently ensured.

Further, since an attractive force by magnetic force acts between the projection and the leg, there is an effect that the end surface of the leg and the end surface of the projection are in close contact with each other. For this reason, it is not necessary to deform the elastic plate to make the legs adhere to each other, so that deformation and internal stress of the elastic plate can be suppressed, and there is an effect of preventing irreparable damage such as breakage.

[Brief description of the drawings]

FIG. 1 is a perspective view of an inkjet head according to the present invention.

FIG. 2 is a sectional view of the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of an arrangement of a pressure generating member.

FIG. 5 is an explanatory diagram showing the effect of the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of an arrangement of a pressure generating member.

FIG. 7 is an explanatory diagram showing the effect of the first embodiment of the present invention.

FIG. 8 is an explanatory view of the arrangement of the projections of the present invention.

FIG. 9 is an explanatory diagram of the effect of the second embodiment of the present invention.

FIG. 10 is an explanatory view of the arrangement of the projections and legs according to the present invention.

FIG. 11 is an explanatory diagram of a second effect of the present invention.

FIG. 12 is an explanatory view of a third embodiment of the present invention.

FIG. 13 is an explanatory diagram of the effect of the third embodiment of the present invention.

FIG. 14 is an explanatory diagram of an effect of the fourth embodiment of the present invention.

FIG. 15 is an explanatory diagram of the effect of the fourth embodiment of the present invention.

FIG. 16 is an explanatory view of a fifth embodiment of the present invention.

FIG. 17 is an explanatory diagram of the effect of the fifth embodiment of the present invention.

FIG. 18 is an explanatory diagram of an inkjet head to which the present invention has been applied.

FIG. 19 is an explanatory view of a conventional arrangement of projections.

FIG. 20 is an explanatory diagram of deformation of a conventional elastic plate.

[Explanation of symbols]

 14. . . . Substrate 30. . . . Elastic plate 33. . . . Nozzle forming substrate 37. . . . Case 45. . . . Cavity section 46. . . . Drive unit 47. . . . Projections 48. . . . Hole 60. . . . Arrow 61. . . . Arrow 90. . . . Adhesive 150. . . . Pressure generating member 151. . . . Pressure generating member 170. . . . Ink chamber 190. . . . Nozzle 220. . . . Projections 221. . . . Projection 230. . . . Ink chamber forming substrate 250. . . . Leg 251. . . . Legs 260. . . . End surface 261. . . . End face 270. . . . End face 271. . . . End face 280. . . . End faces 281. . . . End face

────────────────────────────────────────────────── (5) References JP-A-63-199651 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/045 B41J 2/055

Claims (7)

(57) [Claims] 1. A nozzle, an ink chamber connected to each of the nozzles, and a projection forming one wall of the ink chamber.
An elastic plate having a raised portion and a pressure generating member having legs joined thereto, the pressure generating member displacing the elastic plate via the legs, increasing ink pressure in the ink chamber, and ejecting ink droplets from the nozzles. In the ink jet head for discharging, the leg and the protrusion of the elastic plate are attracted by magnetic force. 2. The elastic plate according to claim 1, wherein at least a protrusion is made of a ferromagnetic material, and said leg is made of a paramagnetic material.
2. The inkjet head according to item 1. 3. The pressure generating member according to claim 1, wherein the adjacent pressure generating members are configured to correct the inclination of the pressure generating member by repelling by a magnetic force of the leg. Ink jet head. 4. The ink jet head according to claim 1, wherein the legs are magnetized in a thickness direction. 5. The ink jet head according to claim 1, wherein the elastic plate and the legs are made of a paramagnetic material. 6. The apparatus according to claim 5, wherein the elastic plate and the legs are arranged so as to face different magnetic poles.
2. The inkjet head according to item 1. 7. The ink jet printer according to claim 1, wherein a length of the leg at a bonding surface with the pressure generating member is longer than a length at a bonding surface of the pressure generating member. head.