WO2012144598A1

WO2012144598A1 - Inkjet head

Info

Publication number: WO2012144598A1
Application number: PCT/JP2012/060717
Authority: WO
Inventors: 昌泰蒔田
Original assignee: コニカミノルタＩｊ株式会社
Priority date: 2011-04-22
Filing date: 2012-04-20
Publication date: 2012-10-26
Also published as: JP5821950B2; JPWO2012144598A1

Abstract

　The purpose of the present invention is to provide an inkjet head capable of suppressing the occurrence of warping caused by differences in the coefficients of thermal expansion of a head tip and a holding member without increasing the number of components and using only one type of adhesive. An inkjet head (H) is provided with: a head tip (1) having a nozzle array in which a plurality of nozzles that eject ink are arranged; and a holding member (4) that holds one side surface of the head tip (1). The inkjet head (H) is characterized by the region in which the holding member (4) and the head tip (1) face each other having alternating adhesion regions (401), in which the holding member (4) and the head tip (1) are adhered to each other, and non-adhesion regions (402), in which both are not adhered to each other, along the nozzle arrangement direction of the nozzle array of the head tip (1).

Description

Inkjet head

The present invention relates to an ink jet head, and more particularly to an ink jet head that can suppress warpage of a head chip even if a holding member having a thermal expansion coefficient different from that of the head chip is provided on only one side surface of the head chip.

Some ink-jet heads contain a head chip having a large number of nozzles for ejecting ink and electrical components such as a drive circuit board electrically connected to the head chip in a housing. This casing also functions as a holding member that holds the head chip and the electrical component inside by bonding the head chip with an epoxy adhesive or the like (hereinafter, in this specification, such a casing is used. The body member is referred to as a holding member).

Since the holding member needs to be a rigid body capable of holding the head chip and the electrical component, it is generally formed of a metal material. In particular, aluminum (aluminum die-casting) is frequently used because of its good thermal conductivity, light weight and easy molding.

Here, the head chip is generally formed of ceramics. Therefore, the holding member formed of a metal material such as aluminum generally has a larger coefficient of thermal expansion than the head chip. From the viewpoint of stably adhering and holding the head chip, it is desirable that the head chip and the holding member be solidly bonded by applying an adhesive to the entire surface of the both, but the head chip and the holding member are In the case where the entire surface is solid-bonded to only one side surface of the head chip, there is a problem that warpage occurs due to the difference in thermal expansion coefficient between the two.

An ink manifold for supplying ink may be bonded to the head chip, but the material of the ink manifold can be selected relatively freely. Depending on the material having the same thermal expansion coefficient as the head chip, It is also relatively easy to form. Therefore, the above problem is much greater in the holding member that is required to be a rigid body than in the ink manifold.

FIG. 11 shows an epoxy-based aluminum plate 200 having a different thickness only on one side of a ceramic head chip 100 (256 nozzles × 1 row, nozzle row length: 36 mm, thickness: 2.5 mm). It shows the total warpage (displacement amount in the Y direction) when a solid surface (FIG. 12) that is solid-bonded using an adhesive is heated to 60 ° C. In FIG. 12, 101 is a nozzle, X is a nozzle row direction, and Y is a thickness direction of the head chip 100 orthogonal to the nozzle row direction X.

When the head chip 100 and the aluminum plate 200 are bonded on the entire surface facing each other, the aluminum plate 200 having a relatively high coefficient of thermal expansion tends to extend along the X direction, which is the length direction. Since the chip 100 has a relatively low coefficient of thermal expansion, it works to prevent the aluminum plate 200 from stretching. As a result, the aluminum plate 200 is warped in the aluminum plate 200 as a result of the fact that only the side opposite to the bonding surface with the head chip 100 tends to extend, and accordingly the head chip 100 also has an arcuate shape along the X direction. To cause a large displacement in the Y direction.

Such a problem of warpage is particularly noticeable in the case of an inkjet head equipped with a heater for heating ejected ink, since it is always affected by a large amount of heat.

As shown in FIG. 11, when the aluminum plate 200 is sufficiently thick, the elongation in the nozzle row direction does not increase. Further, when the aluminum plate 200 is extremely thin, since the force that prevents the head chip 100 from stretching is superior, the displacement in the Y direction can be kept small. However, when used as a holding member, the former case is too thick to cause an increase in size, weight, and cost. In the latter case, it cannot serve as a rigid body that holds the head chip.

The thickness of the holding member that can maintain the function as a rigid body without being unnecessarily thick is preferably about 1 mm. However, since the rigidity of the aluminum plate having a thickness of about 1 mm is smaller than the rigidity of the head chip, the displacement is the largest as shown in FIG. When the thickness of the aluminum plate is sufficiently thick and the rigidity of the aluminum plate exceeds the rigidity of the head chip, the elongation in the nozzle row direction does not increase, and the occurrence of warpage is not a problem. The rigidity is defined by the Young's modulus × the thickness of the holding member or the head chip in the direction perpendicular to the bonding surface.

As one method of suppressing such warpage, a method of forming a symmetrical structure with the head chip sandwiched by adhering members (ink manifold, holding member, etc.) having the same thermal expansion coefficient to both side surfaces of the head chip. There is. However, when there is only one nozzle row formed on the head chip, the ink manifold may be bonded to one side surface of the head chip and the holding member may be bonded only to the other side surface. Even if there are multiple nozzle rows, if a special member such as an ink damper is additionally provided on only one side of the head chip, the holding member is bonded only to the other side of the head chip. You may not be able to. In such a case, warpage occurs due to a difference in thermal expansion coefficient between the head chip and the holding member.

Conventionally, as a technique for dealing with the problem of warping caused by a difference in thermal expansion coefficient, Patent Document 1 discloses disposing layers having substantially the same thermal expansion coefficient on the front and back sides of the substrate so as to be symmetrical. Yes.

Further, in Patent Document 2, the warp of the ink discharge substrate is reduced by bonding the center region of the contact surface between the head discharge substrate and the base substrate with a high-strength adhesive and bonding both end regions with an elastic adhesive. Is disclosed.

JP 2007-30283 A JP 2006-21434 A

In the method of arranging the layers having substantially the same coefficient of thermal expansion on the front and back of the substrate as in Patent Document 1, it is necessary to provide an additional layer only in order to equalize the coefficient of thermal expansion, and the number of parts is reduced. This is not preferable because it increases and causes a complicated manufacturing process and a cost increase.

Also, in the method of using two types of adhesives properly as in Patent Document 2, there is a problem that it takes time and effort to prepare two types of adhesives and apply them separately for each region. In addition, since different types of adhesives have different curing operations, there is a problem that the bonding process becomes complicated.

Therefore, the present invention can suppress the occurrence of warpage due to the difference in thermal expansion coefficient between the head chip and the holding member without increasing the number of parts and using only one kind of adhesive. It is an object to provide an inkjet head.

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

The above problems are solved by the following inventions.

1. An inkjet head comprising a head chip having a nozzle row in which a plurality of nozzles that eject ink are arranged, and a holding member that holds one side of the head chip,
In the region where the holding member and the head chip face each other, an adhesive region where both are bonded and a non-adhesive region where the both are not bonded are alternately provided along the nozzle arrangement direction in the nozzle row of the head chip. An ink jet head characterized by comprising:

2. 2. The ink jet head according to claim 1, wherein each of the adhesion regions is formed in a strip shape extending in a direction orthogonal to a nozzle arrangement direction in the nozzle row of the head chip.

3. 3. The inkjet head according to

claim

1 or 2, wherein the non-adhesive region is provided in a concave shape relative to the adhesive region, so that the holding member and the head chip are kept in non-contact. .

4). The non-adhesion region is provided in a concave shape relative to the adhesion region, so that the holding member and the head chip are kept in a non-contact state, and convex with respect to the non-contact region. 3. The ink jet head according to

claim

1 or 2, further comprising a contact region in which the holding member and the head chip are in contact with each other without being bonded.

5). 5. The ink jet head according to any one of 1 to 4, wherein the adhesion region is located at least in a central portion of the nozzle array of the head chip in the nozzle array direction.

6). 6. The ink jet head according to any one of 1 to 5, wherein a plurality of the adhesion regions are arranged along a nozzle arrangement direction in the nozzle row of the head chip.

7). The bonding region and the non-bonding region are located in plane symmetry with respect to a cross section perpendicular to the nozzle arrangement direction at a central portion of the nozzle array of the head chip in the nozzle row. The ink jet head according to any one of 1 to 6.

8). 8. The ink jet head according to any one of 1 to 7, wherein the non-adhesion region is disposed at least at both end portions in the nozzle arrangement direction of the nozzle row of the head chip.

9. 9. The ink jet head according to any one of 1 to 8, further comprising a heater for heating the ink in the head chip via the holding member.

According to the present invention, it is possible to suppress the occurrence of warpage due to the difference in thermal expansion coefficient between the head chip and the holding member without increasing the number of components and using only one type of adhesive. An ink jet head can be provided.

1 is an exploded perspective view of an inkjet head according to the present invention. The longitudinal cross-sectional view which cut | disconnected the inkjet head which concerns on this invention along the ink discharge direction Sectional view along line (iii)-(iii) in FIG. The top view which shows the part of the holding | maintenance area | region of a holding member Sectional drawing which shows the thickness of the holding | maintenance area | region of a holding member The top view which shows another aspect of a holding | maintenance area | region The top view which shows another aspect of a holding | maintenance area | region The top view which shows another aspect of a holding | maintenance area | region The top view which shows another aspect of a holding | maintenance area | region The graph which shows the displacement amount of the inkjet head which concerns on this invention The graph which shows the displacement amount of the inkjet head which concerns on a prior art example Front view showing the structure of an inkjet head according to a conventional example

An inkjet head according to the present invention includes a head chip having a nozzle row in which a plurality of nozzles that eject ink are arranged, and a holding member that holds the head chip on one side surface.

Generally, the head chip is a hexahedron composed of a nozzle surface and a rear surface opposite to the nozzle surface, and four side surfaces between the nozzle surface and the rear surface. One side surface of the head chip held by the holding member is a side surface excluding the nozzle surface and surfaces disposed at both ends in the nozzle arrangement direction.

The holding member is a housing member that accommodates and holds the head chip or the entire drive circuit board that is electrically connected to the head chip and each drive electrode of the head chip. The holding member is made of a material having rigidity, and a metal material is generally used. The metal material is preferably aluminum or stainless steel in terms of good thermal conductivity, light weight and easy molding, and particularly preferably made of aluminum die cast.

In the region where the holding member and one side surface of the head chip face each other in order to hold the head chip, an adhesive region where they are bonded and a non-adhesive region where they are not bonded are the nozzle arrangement direction in the nozzle row of the head chip Are provided alternately.

According to the present invention, when the head chip and the holding member are heated, due to the difference in thermal expansion coefficient between the two, the larger thermal expansion coefficient tends to extend greatly along the length direction. It can escape in the thickness direction or the width direction at the site of the adhesion region. For this reason, it is suppressed that a head chip deform | transforms into a bow shape.

In the present invention, either the thermal expansion coefficient of the head chip or the thermal expansion coefficient of the holding member may be larger, but the thermal expansion coefficient of the holding member is preferably larger.

In the present invention, it is only necessary to apply the adhesive only to the adhesive region, so that only one type of adhesive is required, and there is no need to use two different types of adhesives differently as in the prior art. In addition, there is no need to provide an additional layer in order to suppress warping of the head chip, and the number of parts does not increase.

The adhesion area and the non-adhesion area may be separated by applying an adhesive only to the adhesion area on the flat surface where the holding member and the head chip face each other. However, it is preferable that the holding member and the head chip are kept in a non-contact manner by providing a relatively concave shape. By making the non-adhesion region relatively concave, the extension of the holding member can be easily released in the thickness direction. In addition, since the adhesive region is relatively convex, the two regions can be clearly distinguished, and the adhesive application operation can be facilitated.

The non-adhesion region is provided in a concave shape relative to the adhesion region, so that the holding member and the head chip are kept in non-contact, and the non-adhesion region is provided in a convex shape with respect to the non-contact region. It is also preferable to have a contact area where the holding member and the head chip are in contact with each other without being bonded. The concave non-contact area can easily release the extension of the holding member in the thickness direction, and the head chip and the holding member are in direct contact by the convex contact area, so that the head chip can be stably supported. In this region, heat transfer between the two can be performed.

The concave non-adhesive region, the convex adhesive region, and the convex contact region can be provided separately on one or both of the surfaces where the holding member and the head chip face each other. To the holding member side only.

The adhesive region is preferably located at least in the center of the nozzle array of the head chip in the nozzle array direction. When the holding member is heated, the holding member extends from the central portion in the nozzle arrangement direction toward both ends in the nozzle arrangement direction. Therefore, in this central portion, the influence of the thermal expansion of the holding member can be almost ignored, and the head chip Stable adhesion can be maintained.

If a plurality of bonding regions are arranged along the nozzle arrangement direction in the nozzle row of the head chip, the head chip can be stably bonded and held at a plurality of locations, so that warpage can be suppressed while increasing the rigidity of the entire inkjet head. It becomes like this.

If the adhesion region and the non-adhesion region are located in plane symmetry with respect to a cross section perpendicular to the nozzle arrangement direction in the central portion of the nozzle array of the head chip in the nozzle arrangement direction, the thermal stress can be symmetrized. This makes it easy to control warpage suppression.

It is preferable that the non-adhesion regions are disposed at both ends in the nozzle arrangement direction in at least the nozzle row of the head chip. Since the elongation of the holding member increases as it goes to both ends of the surface facing the head chip in the nozzle arrangement direction, the influence of the warping of the holding member on the head chip is further increased by making these both ends non-adhesive regions. Can be small.

The present invention can be preferably applied to an inkjet head including a heater that heats ink in a head chip via a holding member. This is because the holding member easily expands due to thermal expansion, and the effect of suppressing warpage can be significantly obtained by the present invention. As the heater, a planar heater such as a film heater can be preferably used.

Next, an example of a specific embodiment of the present invention will be described in more detail with reference to the drawings.

FIG. 1 is an exploded perspective view of an ink jet head according to the present invention, and FIG. 2 is a longitudinal sectional view of the ink jet head according to the present invention cut along an ink discharge direction.

In the figure, H is an ink jet head, and 1 is a head chip. The head chip 1 has a plurality of groove-like channels 11 arranged in parallel. In this head chip 1, a partition wall between channels 11 is formed of piezoelectric ceramics such as PZT, and a shear mode type head chip that discharges ink in the channel 11 by applying a voltage to the partition wall to cause shear deformation. It is. A nozzle plate 12 is attached to the front end surface of the head chip 1, and a nozzle 12 a is opened at a position corresponding to the channel 11. The head chip 1 shown in the present embodiment has a large number of channels 11 arranged in a row, and has only one nozzle row composed of a large number of nozzles 12a corresponding to the channels 11, but there are a plurality of nozzle rows. You may be arranged in parallel.

A cover member 13 that covers the channel 11 from above is provided on the upper surface of the head chip 1. In the cover member 13, an opening 13 a for supplying ink to each channel 11 is formed by exposing the rear end side (end side opposite to the ink ejection direction) of the channel 11 upward.

In this head chip 1, in order to suppress the occurrence of warping of the head chip 1 alone due to the influence of heat, a member in which groove-like channels 11 are arranged in parallel and a cover member 13 that covers the channels 11 from above are: For example, it is preferable that the thermal expansion coefficients of the two materials are made uniform by forming the same material or forming different materials with the same or similar thermal expansion coefficients.

2 is a drive circuit board on which a drive IC 21 for applying a drive signal to a drive electrode (not shown) provided in each channel 11 of the head chip 1 is mounted. The drive circuit board 2 is joined to the rear end portion of the head chip 1 by a flexible wiring board 22. Reference numeral 23 denotes a connector.

Reference numeral 3 denotes an ink manifold, and one surface facing the head chip 1 becomes a concave portion by a synthetic resin such as engineering plastic whose thermal expansion coefficient along the nozzle array direction is the same as or close to the thermal expansion coefficient along the same direction of the head chip 1. It is formed in a box shape. The ink manifold 3 is adhered to the cover member 13 on the upper surface of the head chip 1 so as to cover the opening 13a, thereby forming a common ink chamber 3a therein, and the ink in the common ink chamber 3a is formed. Can be supplied to each channel 11 through the opening 13a. An ink supply pipe (not shown) is connected to the ink manifold 3 so that ink from the ink tank is supplied.

Reference numeral 4 denotes a holding member, which is formed in a plate shape by aluminum die casting having a thermal expansion coefficient larger than that of the head chip 1, and is the width of the head chip 1, that is, the arrangement direction of the nozzles 12a in the head chip 1 (hereinafter referred to as nozzle arrangement). It is wider than the width (length) of the direction), and has a length extending from the nozzle plate 12 to the entire rear end of the drive circuit board 2. The holding member 4 bonds the head chip 1 and the drive circuit board 2 electrically connected to the head chip 1 by bonding to the lower surface 1a of the head chip 1 (the surface opposite to the bonding surface of the ink manifold 3). It is held by its rigidity.

Note that the plate-like portion that is the region for supporting the head chip 1 and the drive circuit board 2 occupying the largest area in the holding member 4 is actually formed very thin, but in the drawing, the structure is easily visualized. For this reason, it is exaggerated and thickly illustrated.
Details of the bonding structure between the head chip 1 and the holding member 4 will be described later.

Support walls 41 that support both ends of the head chip 1 in the nozzle array direction from the outside are provided on both sides of the holding member 4. In the holding member 4, a region 4 a between the support walls 41 is a holding region 400 that faces the lower surface 1 a of the head chip 1 and accommodates and holds the head chip 1.

A stepped portion 41 a is provided at the same height as the thickness of the head chip 1 on the inner side in the height direction of both support walls 41. The ink manifold 3 is formed wider than the head chip 1, and the both ends of the ink manifold 3 are in contact with the step portion 41 a, so that the head chip 1 is sandwiched between the holding region 400 of the holding member 4. It has become.

5 is an exterior cover, which is formed of a synthetic resin and is detachably attached to the holding member 4. The exterior cover 5 has a size that protects the drive circuit board 2 between the ink manifold 3 and the holding member 4, and an opening 5 a that exposes the connector 23 to the outside is formed at the rear end. ing.

6A and 6B are heaters, which are attached to the ink manifold 3 and the holding member 4. Here, a film heater is used in all cases. The heater 6A is attached to the upper surface of the ink manifold 3 (the surface opposite to the surface bonded to the head chip 1), thereby heating the ink in the common ink chamber 3a to a predetermined temperature via the ink manifold 3. The heater 6B is attached to the lower surface of the holding member 4 (the opposite surface of the holding region 400), thereby heating the head chip 1 via the holding member 4 and causing the ink in the head chip 1 to be heated to a predetermined temperature. Heat to.

Next, the bonding structure between the holding member 4 and the head chip 1 will be further described with reference to FIGS.

3 is a cross-sectional view taken along line (iii)-(iii) in FIG. 2, FIG. 4 is a plan view showing a portion of the holding region 400 of the holding member 4, and FIG. 5 is a cross-sectional view showing the thickness of the holding region 400. FIG.

The holding area 400 of the holding member 4 faces the lower surface 1a of the head chip 1. The holding area 400 is provided with an adhesion area 401 where the holding member 4 and the head chip 1 are bonded, and a non-adhesion area 402 where the both are not bonded, which are arranged in the nozzle arrangement direction of the head chip 1 (FIG. 3). 4 are arranged so as to alternate along the horizontal direction in FIG.

The adhesion region 401 is a region having a portion to be bonded to the head chip 1 along the ink discharge direction (vertical direction in FIG. 4) orthogonal to the nozzle arrangement direction of the head chip 1. Here, an adhesive region 401 extending in a band shape having a constant width in the direction along the ink discharge direction is shown. Since the extension direction of the holding member 4 due to thermal expansion is a direction along the nozzle arrangement direction of the head chip 1, the extension of the holding member 4 is achieved by bonding in a band shape in a direction orthogonal to the nozzle arrangement direction of the head chip 1. The head chip 1 can be stably adhered and held while being hardly affected by the above.

Here, three adhesion regions 401 are formed in a band shape having a predetermined width. One of the bonding regions 401 is arranged at a position corresponding to the central portion (O ₁ in FIG. 3 and O _{2 in} FIG. 4) of the head chip 1 in the nozzle arrangement direction, and the two bonding regions 401 are These are disposed on both sides of the non-adhesive region 402, respectively. Thereby, the adhesion region 401 and the non-adhesion region 402 are positioned symmetrically with respect to a cross section (plane passing through the central portions O ₁ and O ₂ ) perpendicular to the nozzle arrangement direction in the central portion O ₁ or O ₂ . Yes.

Each adhesive region 401 is formed in a convex shape protruding from the surface of the holding region 400 toward the head chip 1 side. For this reason, the non-adhesion area | region 402 adjacent to the adhesion | attachment area | region 401 becomes a comparatively concave shape, and it forms in the step shape between both. The adhesive region 401 is adhered to the lower surface 1a of the head chip 1 by applying an adhesive on the convex upper surface.

If the protruding height of the adhesive region 401 is too high, the distance from the head chip 1 is increased in the non-adhesive region 402 that is relatively concave, and heat from the heater 6B is not easily transmitted to the head chip 1. The thickness is preferably about 50 to 300 μm.

Note that the convex adhesive region 401 only has to protrude relative to the non-adhesive region 402, and the non-adhesive region 402 is recessed from the surface of the holding region 400 so that the adhesive region 401 is relatively convex. You may make it become a shape.

The width of the non-adhesion region 402 in the nozzle arrangement direction is formed to be equal to or greater than the width of the adhesion region 401 in the nozzle arrangement direction. The relationship between the widths of the adhesion region 401 and the non-adhesion region 402 is that the adhesion region 401 and the non-adhesion on the plurality of transverse lines L1 to Ln (see FIG. 4) crossing the holding region 400 along the nozzle arrangement direction When the width of the region 402 is viewed, it is sufficient that the width is satisfied on any one of the plurality of transverse lines L1 to Ln. Preferably, the non-adhesive region is also present on any transverse line. That is, the width 402 is formed to be equal to or larger than the width of the adhesive region 401 in the nozzle arrangement direction.

In addition, the total width in the nozzle arrangement direction of the non-adhesion area 402 in the holding area 400 (total value of the widths of the non-adhesion areas 402) is the total width of the adhesion area 401 in the nozzle arrangement direction (total value of the widths of the adhesion areas 401) That's it.

As long as this condition is satisfied, the specific width and arrangement interval of the bonding region 401 and the non-bonding region 402 are not particularly limited. However, if the area of the bonding region 401 is small, the head chip 1 is stably bonded and held. Since it becomes difficult to suppress the warp of the head chip 1 when the holding member 4 is stretched as the size of the holding member 4 increases, the nozzle arrangement of the adhesion area 401 with respect to the entire width of the holding area 400 in the nozzle arrangement direction becomes difficult. The total width in the direction is preferably 15 to 50%.

The specific number of the adhesive regions 401 is not particularly limited, but is preferably 3 to 5.

In the non-bonding region 402 of the holding member 4, the thickness t of the holding member in the direction perpendicular to the bonding surface (when the bonding region 401 is formed in a convex shape, the non-bonding region 402 has a concave shape as shown in FIG. 5. If the thickness of the bonding region 402 is too small, it will be difficult to perform the function as a rigid body. If the thickness is too large, the heat transfer efficiency will be reduced and the inkjet head H will be enlarged and increased in weight. It is preferably 1.5 mm, and more preferably 0.8 mm to 1.0 mm.

In such an ink jet head H, the holding member 4 having a larger thermal expansion coefficient than the head chip 1 is elongated in the nozzle arrangement direction by heating by the heater 6 </ b> B, and the adhesive region 401 is bonded to the head chip 1. Although the force which prevents expansion | extension works, since the adhesion | attachment area | region 401 and the non-adhesion area | region 402 are alternately formed between the head chip 1 and the holding member 4, the holding member 4 is the site | part of the non-adhesion area | region 402. In this case, the bending force can be deformed without being restricted by the adhesion with the head chip 1, and the force to be extended escapes in the thickness direction or the width direction (nozzle arrangement direction) of the holding member 4. As a result, the holding member 4 is suppressed from being deformed into a bow shape, and the warp of the head chip 1 is also suppressed.

The adhesive is applied only to the upper surface of each bonding area 401. Each adhesive region 401 is formed with an appropriate number of adhesive injection holes 403 so as to penetrate the holding member 4. The head chip 1 is attached to the holding region 400, its lower surface 1 a and the upper surface of the adhesive region 401. In the state of contacting, an adhesive layer is formed with the head chip 1 by injecting an adhesive into the adhesive injection hole 403 from the opposite side of the holding region 400.

It is preferable to bond the holding member 4 and the head chip 1 by curing the adhesive applied to the bonding region 401 at the same temperature as the use temperature of the inkjet head H. Thereby, the thermal stress of the adhesive layer in a use state can be relieved. The operating temperature is generally a temperature generated by the inkjet head itself by driving. However, in the case where the holding member 4 has the heater 6B as in the inkjet head H shown in the present embodiment, the heating temperature is the heating temperature of the heater 6B. Is done.

The heater 6B is attached to the holding member 4 after the injection and curing operations of the adhesive.

In the holding area 400, non-adhesive areas 402 are arranged at both ends in the nozzle arrangement direction. For this reason, the head chip 1 is not bonded to the holding member 4 at both ends of the holding area 400 in the nozzle arrangement direction.

In the non-adhesion region 402 located at both ends, similarly to the adhesion region 401, there is a contact region 402a formed in a convex shape protruding from the surface of the holding region 400 toward the head chip 1 side. . Each contact region 402a is formed in a strip shape that is narrower than the width in the nozzle row direction of the non-adhesive region 402 at both ends, and extends in the ink ejection direction. The upper surface of each contact region 402a is formed so as to be in direct contact with the lower surface 1a of the head chip 1 without being bonded. That is, the contact area 402a has a protruding height of (the protruding height of the adhesive area 401) + (the thickness of the adhesive layer after curing).

On the other hand, the portions other than the convex contact region 402a in the non-adhesion region 402 are non-contact regions that do not contact the head chip 1.

The head chip 1 is stably supported by the contact area 402a in the vicinity of both ends in the nozzle arrangement direction. Moreover, even when the adhesion region 401 is formed in a convex shape as in the present embodiment, the heat of the heater 6B can be directly transmitted from the holding member 4 to the head chip 1 at the contact region 402a.

FIG. 6 shows another aspect of the holding area 400. Parts having the same reference numerals as those in FIG. 4 indicate parts having the same configuration.

If the adhesive region 401 in the holding region 400 has a portion to be bonded to the head chip 1 along the ink discharge direction (vertical direction in FIG. 6) orthogonal to the nozzle arrangement direction of the head chip 1, The holding region 400 may not extend over the entire length in the ink discharge direction, and may be divided into a plurality of portions along the ink discharge direction.

In this embodiment, since the adhesion area and the non-adhesion area have areas that are alternately arranged not only in the nozzle arrangement direction but also in the ink ejection direction, thermal expansion between the head chip and the holding member is prevented. The difference can be absorbed more reliably.

FIG. 7 shows still another aspect of the holding area 400. Parts having the same reference numerals as those in FIG. 4 indicate parts having the same configuration.

The adhesive region 401 in the holding region 400 is not disposed on the central portion (O in FIG. 7) of the head chip 1 in the nozzle arrangement direction, and one adhesive region is provided symmetrically on both sides so as to sandwich the central portion O. It is arranged one by one. As described above, it is sufficient that the adhesion regions 401 have alternately the non-adhesion regions 402 along the nozzle arrangement direction in the holding region 400, and the number thereof is also arbitrary.

FIG. 8 shows still another aspect of the holding area 400. Parts having the same reference numerals as those in FIG. 4 indicate parts having the same configuration.

As in FIG. 7, the bonding regions 401 in the holding region 400 are arranged one by one symmetrically on both sides so as to sandwich the central portion O, but in the non-bonding region 402 between the bonding regions 401 ( Here, on the central portion O), similarly to the adhesive region 401, a contact region 402a formed in a convex shape protruding from the surface of the holding region 400 toward the head chip 1 side is provided.

FIG. 9 shows still another aspect of the holding area 400. Parts having the same reference numerals as those in FIG. 4 indicate parts having the same configuration.

In this embodiment, each non-adhesive region 402 (excluding the contact region 402a) in the holding region 400 has an opening 402b formed so as to penetrate the holding member 4, so that the head chip and the holding member are held. The difference in thermal expansion from the member can be absorbed more reliably.

<Example> (Invention)
Head chip structure material: PZT
Number of nozzles: 256
Number of nozzle rows: 1
Thickness T (see FIG. 3): 2.5 mm
Thermal expansion coefficient in the nozzle arrangement direction: 9 μm · m ⁻¹ · K ⁻¹

Structural material of holding member : Aluminum Size: A: 50 mm × B: 70 mm × C: 10 mm (see FIGS. 2 and 3)
Thickness t (see FIG. 5): 0.8 mm
Number of bonded areas: 3
Adhesion area width: 2.5 mm
Adhesion area spacing: 6 mm
Projection height of the bonding area: 0.2 mm
Thermal expansion coefficient in the nozzle array direction: 23.4 μm · m ⁻¹ · K ⁻¹

Each of the adhesive regions is formed in a band shape in the same manner as in FIG. 4, and one of them is located in the center of the holding member in the width direction (head chip nozzle arrangement direction), and the above-mentioned interval is provided on both sides thereof. And one for each.

Further, in each non-adhesion region located at both ends in the width direction, a contact region (width 2.5 mm) was formed so as to protrude in contact with the lower surface of the head chip in the same manner as in FIGS.

A head chip was attached to the holding area of this holding member, and was bonded at the bonding area using an epoxy adhesive. The thickness of the adhesive layer was 50 μm, and curing was performed at room temperature (20.5 ° C.). In addition, a film heater was attached to the surface of the holding member opposite to the bonding surface of the head chip.

<Comparative example>
A laminated structure of the head chip and the holding member was produced in the same manner as in the example except that a holding member having a thickness t of 0.8 mm and a uniform thickness was used and the entire surface was bonded to the head chip.

For the laminated structure of the obtained head chip and holding member, the displacement amount in the Y direction (thickness direction orthogonal to the nozzle row) in the X direction (nozzle row direction) when the film heater is heated to 60 ° C. Measuring device manufactured by company: measured using NEXIV.

FIG. 10 shows the measurement results of the laminated structure of the present invention.

In the laminated structure of the comparative example, as in the case where the conventional 0.8 mm thick aluminum plate shown in FIG. According to the invention, the amount of displacement is limited to about 5 μm at the maximum, and warpage is suppressed.

In addition, using a holding member having a thickness t of 0.5 mm and 3 mm, similarly, a laminated structure of a head chip and a holding member was produced and evaluated, and the displacement amount of the laminated structure of the present invention was a laminated structure of a comparative example. It is confirmed that the warpage is suppressed by being smaller than the displacement amount of the object.

H: Inkjet head 1: Head chip 1a: Lower surface 11: Channel 12: Nozzle plate 12a: Nozzle 13: Cover member 13a: Opening portion 2: Drive circuit board 21: Drive IC
22: Flexible wiring board 23: Connector 3: Ink manifold 3a: Common ink chamber 4: Holding member 41: Support wall 41a: Step portion 400: Holding area 401: Adhesive area 402: Non-adhesive area 402a: Contact area 5: Exterior cover 5a:

Opening

6A, 6B: Heater

Claims

An inkjet head comprising a head chip having a nozzle row in which a plurality of nozzles that eject ink are arranged, and a holding member that holds one side of the head chip,
In the region where the holding member and the head chip face each other, an adhesive region where both are bonded and a non-adhesive region where the both are not bonded are alternately provided along the nozzle arrangement direction in the nozzle row of the head chip. An ink jet head characterized by comprising:
2. The ink jet head according to claim 1, wherein the adhesion region is formed in a strip shape extending in a direction orthogonal to a nozzle arrangement direction in the nozzle row of the head chip.
The inkjet according to claim 1 or 2, wherein the non-adhesion region is provided in a concave shape relative to the adhesion region, whereby the holding member and the head chip are kept in non-contact. head.
The non-adhesion region is provided in a concave shape relative to the adhesion region, so that the holding member and the head chip are kept in a non-contact state, and convex with respect to the non-contact region. The inkjet head according to claim 1, further comprising a contact region in which the holding member and the head chip are in contact with each other without being bonded.
The inkjet head according to any one of claims 1 to 4, wherein the adhesion region is located at least in a central portion in a nozzle arrangement direction of the nozzle row of the head chip.
6. The inkjet head according to claim 1, wherein a plurality of the adhesion regions are arranged along a nozzle arrangement direction in the nozzle row of the head chip.
The adhesion region and the non-adhesion region are located in plane symmetry with respect to a cross section perpendicular to the nozzle arrangement direction in a central portion of the nozzle array of the head chip in the nozzle arrangement direction. Item 7. The ink jet head according to any one of Items 1 to 6.
The inkjet head according to any one of claims 1 to 7, wherein the non-adhesion region is disposed at least at both ends of the nozzle array of the head chip in the nozzle array direction.
9. The ink jet head according to claim 1, further comprising a heater for heating the ink in the head chip via the holding member.