JPH11268286A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a nozzle cover accurately to the head body side by an arrangement wherein the longitudinal central part at an opening corresponding to a nozzle forming member and the inner circumferential end of the opening touch the nozzle forming member at first. SOLUTION: When a nozzle cover 4 is bonded to a channel forming member 18, ink oozing in from the nozzle surface is shut out to prevent electric short circuit between an FPC cable 34 and the electrode pattern 15 on a substrate 11. When a diaphragm 17 and a nozzle plate 19 are made of Ni, strength is low for sealant and a photosensitive resin is bonded to the channel forming member 18 with sufficient strength. When nozzle cover 4 is applied to the head body side, claw of the nozzle cover 4 engages with a recess 3-7 in a head case 3 to apply a force for fitting the nozzle plate 19 and the nozzle cover 4 tightly. Even if an external force is applied to the nozzle cover 4, it is prevented from floating through engagement of the claw and the recess 37 thus the enhancing reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head, and more particularly, to an ink jet head having a nozzle cover for covering a peripheral portion of a nozzle surface of a nozzle forming member having a plurality of nozzles and a side wall of a head body.

[0002]

2. Description of the Related Art In general, as an ink jet head used in an ink jet recording apparatus used as an image forming apparatus such as a printer, a facsimile, a copying apparatus, etc., a plurality of nozzles for discharging ink droplets and an ink liquid chamber in which each nozzle communicates are formed. Energy generation including a flow path forming member and an electromechanical conversion element such as a piezoelectric element or an electrothermal conversion element such as a heater that generates energy for discharging ink droplets from nozzles by pressurizing ink in each ink liquid chamber. Means (actuator element), and the actuator element is driven in accordance with the image information to discharge ink droplets from required nozzles to record an image.

[0003] Such an ink jet head is structurally divided into an edge shooter type in which ink droplets are ejected from the end face side of a stack of head constituent members, and a side shooter type in which a circular nozzle is formed in a nozzle forming member. Can be roughly divided into As the side shooter type ink jet head, for example, Japanese Patent Laid-Open No.
As described in Japanese Patent No. 5099, a flow path forming member for forming a flow path pressurized by an actuator element is laminated on a drive unit having an actuator element housed in a head case, and the flow path is formed. A nozzle forming member having a nozzle formed thereon is laminated on the member, and further provided with a nozzle protecting member (nozzle cover) integrally formed so as to be fitted to an outer peripheral portion of the nozzle forming member and a part of a side surface of the head case. It has been known.

In an ink-jet head, if ink accumulation occurs on the nozzle surface, the flying direction of the ink droplet may be deviated. For example, the nozzle surface may be wiped by the reliability maintaining mechanism to flow out of the nozzle. Capping or the like is performed so as to prevent the ink pool from being generated by the dripping or dripping ink, and to prevent the ink from drying and blocking the nozzles. In addition, since the characteristics of the nozzle surface affect the ejection characteristics of the ink droplets, a water-repellent treatment is generally applied to prevent the ink from adhering to the nozzle surface.

As a result, the nozzle surface of the ink jet head is always wet with the ink. In particular, in the side shooter type ink jet head,
The ink that has flowed out of the nozzle surface easily penetrates into the drive unit composed of the actuator element, etc., and if the ink adheres to the electrical connection of the drive unit, etc., a short circuit occurs and the actuator element cannot be driven, and ink droplets can be ejected. Therefore, it is essential to prevent ink flowing out of the nozzle surface.

Conventional ink jet heads of the side shooter type are provided with a nozzle protection member for covering the peripheral portion of the nozzle surface in order not to be aware of the problem of preventing ink flowing out from the nozzle surface. However, the nozzle cover is merely structured to be attached to the head case by an adhesive or mechanical fitting. for that reason,
It is not possible to prevent ink flowing out of the gap between the nozzle surface and the nozzle protection member, and it is not possible to secure electrical reliability, for example, the ink may penetrate into the electrical connection part.

Therefore, in order to prevent ink from adhering to the electrical connection portion due to the outflow or dripping of ink from the peripheral portion of the nozzle surface, the peripheral portion of the nozzle forming member (nozzle surface) and the head body side (particularly the A nozzle cover that also serves as a head case that covers the side wall portion of the unit portion). This nozzle cover is joined to the flow path forming member, and the engaging claw portion provided on the nozzle cover is provided in a recess provided on the spacer member side wall portion. There has been proposed an ink jet head that is engaged and locked (see Japanese Patent Application Laid-Open No. 9-300633).

[0008]

By the way, in the ink jet head to which the above-mentioned nozzle cover is mounted, the nozzle surface of the nozzle forming member has a low sealing property such as a water-repellent treatment. Ink may penetrate into the inside from the gap between the nozzle cover and the nozzle.

As means for mounting the nozzle cover on the head main body side, when an engaging claw is formed on the inner surface side of the nozzle cover to be locked and held in the recess of the spacer member (see the above publication). The nozzle cover must be mounted on the spacer member accurately and reliably.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made to improve the sealing property between a nozzle cover and a nozzle forming member, or to enable the nozzle cover to be attached to the head body with high accuracy. It is an object of the present invention to be able to surely mount the head on the head body side.

[0011]

In order to solve the above-mentioned problems, an ink jet head according to a first aspect of the present invention includes a nozzle cover that covers a peripheral portion of a nozzle surface of a nozzle forming member having a plurality of nozzles and a side wall portion of the head. In the ink jet head, when the nozzle cover is mounted on the head main body side, a longitudinal center portion of an opening formed corresponding to the nozzle forming member and an inner peripheral end of the opening are first formed on the nozzle forming member. It was configured so as to be in contact with

According to a second aspect of the present invention, in the inkjet head of the first aspect, the nozzle cover is warped such that a central portion in the longitudinal direction of the opening and an inner peripheral end of the opening project toward the head body. Configuration.

According to a third aspect of the present invention, there is provided an ink jet head including a nozzle cover for covering a peripheral portion of a nozzle surface of a nozzle forming member having a plurality of nozzles and a side wall portion of the head. A dovetail portion is formed, and an engaging recess for engaging the claw portion is formed in a side wall portion of the spacer member holding the head body, and a guide groove for guiding the engaging claw portion is formed.

According to a fourth aspect of the present invention, in the ink jet head of the third aspect, the guide groove of the spacer member is formed so that the groove width is reduced toward the end side in the mounting direction.

According to a fifth aspect of the present invention, in the inkjet head according to the third or fourth aspect, a bending angle of the engaging claw portion of the nozzle cover with respect to an inner surface is set to 30 ° or less.

According to a sixth aspect of the present invention, in the inkjet head of any of the third to fifth aspects, a force required for mounting the engagement claw portion of the nozzle cover to the head body side is 3 kg / f or less. The length and width were formed.

According to a seventh aspect of the present invention, in the ink jet head according to any one of the third to sixth aspects, the width of the plate supporting the engaging claw of the nozzle cover is set to １ ／ of the width of the engaging claw. The configuration is as described above.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view showing an example of an ink jet head to which the present invention is applied, and FIG. 2 is a sectional view of a main part of the ink jet head.

This ink jet head comprises a drive unit 1, a liquid chamber unit 2, a head case 3, and a nozzle cover 4. The drive unit 1 has a plurality of piezoelectric elements 12 joined and arranged in two rows on an insulating substrate 11 made of ceramic, glass epoxy resin or the like, and surrounds the periphery of the piezoelectric elements 12 in each of these rows to form a liquid chamber unit. 2
The frame 13 which supports is joined. Also, the substrate 11
The common electrode pattern 14 and the individual electrode pattern 15 are on
Is provided. The common electrode pattern 14 is electrically connected to each other by filling a conductive adhesive in a hole 16 provided in the frame 13.

The liquid chamber unit 2 includes a vibration plate 17, a flow path forming member 18, and a nozzle plate 19 serving as a nozzle forming member.
Are laminated and thermally fused. The diaphragm 17 is formed from a diaphragm 20 displaced by the piezoelectric element 12 and a base 21 joined to the frame 3, and the diaphragm 20 has a convex portion 22 and a thin film portion 2 joined to the piezoelectric element 12.
3.

The flow path forming member 18 is formed of a two-layer photosensitive resin film or the like, and includes the diaphragm 17 and the nozzle plate 1.
9, the pressurized liquid chamber 25 facing the piezoelectric element 12, the common liquid chamber 26 located on both sides of the pressurized liquid chamber 25, and the pressurized liquid chamber 2
An ink supply path 27 which also serves as a fluid resistance part that communicates the common liquid chamber 26 with the common liquid chamber 26 is formed. A large number of nozzles 28 are formed on the nozzle plate 19, and a water-repellent film such as Teflon is formed on the nozzle surface so that wiping can be performed.

The head case 3 includes a spacer member 31 for holding the drive unit 1 and the liquid chamber unit 2 (these are referred to as a “head body”) and a head drive I.
It comprises a PCB substrate 32 having C33 and the like, and connects the PCB substrate 32 and the piezoelectric element 12 of the drive unit 1 via an FPC cable 34.

A nozzle cover 4 is provided so as to cover the side wall of the drive unit 1 and the liquid chamber unit 2, that is, the head body. This nozzle cover 4
As shown in detail in FIG. 2, it is joined to the flow path forming member 18 by a joining agent 35. This bonding is performed by applying a bonding agent 35 to a region corresponding to the outer peripheral portion of the nozzle plate 19 on the inner surface of the nozzle cover 4 with a dispenser. As the bonding agent, a sealing agent that does not elute or swell with the ink is suitable, and for example, an epoxy-based adhesive or a silicon-based sealing agent is suitable.

When the bonding agent 35 made of these sealants is applied to the inner surface of the nozzle cover 4 to a height of 0.15 to 0.3 mm, a part of the bonding agent 35 penetrates into the interface between the nozzle plate 19 and the nozzle cover 4 and is partially absorbed. 4, a uniform film is formed around the opening, and most of the other bonding agent 35 penetrates in the thickness direction of the liquid chamber unit 2 to bond the flow path forming member 18 and the nozzle cover 4.

As described above, by joining the nozzle cover 4 and the flow path forming member 18, the ink penetrating from the nozzle surface is completely shut off, and the electrical connection between the FPC cable 34 and the electrode pattern 15 of the substrate 11 is made. A short circuit can be prevented. When the vibration plate 17 and the nozzle plate 19 are formed of Ni, the bonding strength with the sealant is not sufficient, and the vibration plate 17 and the nozzle plate 19 are bonded to the flow path forming member 18 formed of a photosensitive resin (main component: acrylic resin). Thereby, sufficient bonding strength can be obtained.

As shown in FIG. 1 and FIG. 3A, an inwardly engaging engaging claw 36 serving as an engaging means is provided on a side portion of the nozzle cover 4, while a spacer of the head case 3 is provided. As shown in FIGS. 1 and 3B, the engaging recess 3 with which the engaging claw 36 of the nozzle cover 4 engages is formed on the side wall of the member 31.
7 are provided.

With such a structure, the nozzle cover 4
3c, the engaging claw 36 of the nozzle cover 4 engages with the engaging recess 37 of the spacer member 31 of the head case 3 as shown in FIG. Even when a force is applied in the direction in which the nozzle cover 4 is in close contact with the nozzle cover 4 to heat and cure the bonding agent 35, bonding can be performed without using a pressing jig or the like. And
When an external force is applied to the nozzle cover 4, even if the strength of the bonding agent 35 alone is insufficient, the nozzle cover 4 does not float due to the mechanical coupling between the engagement claw 36 and the engagement recess 37.
Reliability is improved.

As shown in FIG. 4, when the nozzle cover 4 is mounted on the head body side, the center of the opening 4a formed corresponding to the nozzle plate 19 in the longitudinal direction and the inner periphery of the opening 4a are formed. Each part is formed in a warped shape such that the side end first comes into contact with the surface (nozzle surface) of the nozzle plate 19.

By forming the nozzle cover 4 in such a shape, the engaging claw 36 provided on the nozzle cover 4 is provided.
Effect can be fully exhibited, and the nozzle cover 4
The gap between the nozzle and the nozzle plate 19 is extremely small, and the amount of the sealant 35 that has been circulated in the gap is larger, so that the flow path forming member 1
As a result, the sealability and adhesiveness are improved. At the same time, the distance from the nozzle surface of the nozzle plate 19 to the front surface of the nozzle cover 4 is reduced, and dirt due to friction with the printing medium is reduced. That is, the distance between the head and the printing medium can be reduced.

The length L of the plate removing portion 4b supporting the engaging claw portion 36 of the nozzle cover 4 is formed to be at least half the width W of the engaging claw portion 36, and the engagement of the nozzle cover 4 is prevented. The inclination angle (bending angle) θ of the claw portion 36 from the inner wall surface is set to 30 ° or less.

That is, the engaging claw portion 36 of the nozzle cover 4
If the ink adheres to the nozzle plate 19, the ink penetrates into the inside of the nozzle plate 19, so that it is preferable that the position of the engaging claw portion 36 is as far away from the nozzle plate 19 as possible. Since the thickness of the portion is reduced, plastic deformation occurs when the nozzle cover 4 is inserted and mounted, so that the nozzle cover 4 cannot be securely mounted. Therefore, as in the present embodiment, the length L of the plate removing portion 4b is formed to be equal to or more than の of the width W of the engaging claw portion 36, and the bending angle of the engaging claw portion 36 is defined. The nozzle cover 4 can be surely mounted and held by preventing plastic deformation of the engaging claw portion 36 while preventing intrusion.

Further, as described above, the inclination angle (bending angle) θ of the engagement claw portion 36 of the nozzle cover 4 from the inner wall surface is formed to be 30 ° or less, and the width W and the length of the engagement claw portion 36 are set. L1 is formed such that the force at the time of mounting and insertion is 3 kgf or less. On the other hand, as shown in FIG. 5, the spacer member 31 is formed with two guide grooves 38 for guiding the distal end of the engaging claw 36 in the direction in which the nozzle cover 4 is inserted. The guide groove 38 is formed so that the groove width becomes narrower toward the mounting end side (the engaging recess 37 side).

As described above, the nozzle cover 4 can be inserted and mounted at a pressure of 3 kgf or less.
Can be inserted and mounted by hand, and by providing the guide groove 38 in the spacer member 31, the positioning accuracy when mounting the nozzle cover 4 can be ensured. Thereby, when the nozzle cover 4 is mounted, the FPC 3
4 can be prevented from being cut, and the nozzle cover 4
Can reduce the number of mounting steps.

That is, conventionally, when the nozzle cover 4 is mounted, the nozzle cover 4 is mounted on a jig provided with a mechanism for positioning and pushing. However, an error exceeding the positioning accuracy occurs due to the accumulation of errors in the process of assembling the head.
The FPC 34 may be cut when the nozzle cover 4 is inserted and mounted. On the other hand, by allowing the nozzle cover 4 to be inserted and mounted by hand while ensuring the positioning accuracy as in the present embodiment, no special jig is required, and the positioning accuracy is ensured. In addition, the FPC 34 is not cut when the nozzle cover 4 is inserted and mounted.

[0035]

As described above, according to the ink jet head of the first aspect, the nozzle cover for covering the periphery of the nozzle surface of the nozzle forming member having the plurality of nozzles and the side wall of the head is mounted on the head body side. When the nozzle forming member is formed, the central portion in the longitudinal direction of the opening formed corresponding to the nozzle forming member and the inner peripheral end portion of the opening are formed in a shape that first comes into contact with the nozzle forming member. The gap between the sealant and the sealing agent is reduced, and a large amount of the sealant flows to the side wall surface on the head main body side, thereby improving the sealing property and the adhesive property.

According to the ink jet head of the second aspect, in the ink jet head of the first aspect, the nozzle cover is configured such that a central portion in the longitudinal direction of the opening and an inner peripheral end of the opening protrude toward the head body. Due to the warped configuration, the gap between the nozzle forming member surface and the nozzle cover is reduced, so that the sealant spills more on the side wall surface on the head main body side, and the sealability and adhesiveness are improved.

According to the ink jet head of the third aspect, an engaging claw projecting inward is formed on the nozzle cover which covers the periphery of the nozzle surface of the nozzle forming member having a plurality of nozzles and the side wall of the head. The spacer member holding the main body is formed with an engaging concave portion for engaging the engaging claw portion and a guide groove for guiding the engaging claw portion, so that the nozzle cover is securely attached to the head main body side. Can be mounted with high accuracy.

According to the ink jet head of the fourth aspect, in the ink jet head of the third aspect, the guide groove of the spacer member is formed to have a narrow groove width toward the end side in the mounting direction. The positional displacement at the time can be absorbed, and fine positioning is not required.

According to the ink jet head of claim 5, in the ink jet head of claim 3 or 4, the bending angle of the engaging claw portion of the nozzle cover with respect to the inner wall surface is set to 30 ° or less. The plastic deformation of the claw can be prevented, and the nozzle cover can be securely mounted.

According to the ink jet head of the sixth aspect, in the ink jet head of any one of the third to fifth aspects, the engaging claw portion of the nozzle cover requires a force required for mounting on the head body side of 3 kg / f or less. Because the length and width of the nozzle cover are configured, the nozzle cover can be attached by hand, and the number of steps can be reduced.
The signal transmission means is not damaged during mounting.

According to the ink jet head of claim 7, in the ink jet head of any one of claims 3 to 6, the width of the plate for supporting the engaging claw of the nozzle cover is set to 1/2 of the width of the engaging claw. With the above configuration,
Deformation of the portion supporting the engagement claw can be prevented, and the nozzle cover can be securely mounted.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an example of an inkjet head to which the present invention is applied.

FIG. 2 is an enlarged sectional view of a main part of the inkjet head.

FIG. 3 is an enlarged explanatory view of an essential part for explaining an assembled state of a nozzle cover and a head body side of the inkjet head.

FIG. 4 is an enlarged perspective view of a nozzle cover of the inkjet head.

FIG. 5 is an enlarged perspective view of a spacer member of the inkjet head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Drive unit, 2 ... Liquid chamber unit, 3 ... Head case, 4 ... Nozzle cover, 4a ... Opening, 11 ... Substrate, 1
2: Piezoelectric element, 13: Frame, 17: Vibration plate, 18:
Flow path forming member, 19: nozzle plate, 31: spacer member, 34: FPC cable, 35: bonding agent, 36: engaging claw portion, 37: concave portion, 38: guide groove.

Claims (7)

[Claims] 1. An ink jet head having a nozzle cover that covers a peripheral portion of a nozzle surface of a nozzle forming member having a plurality of nozzles and a side wall portion of a head main body. An ink jet head, wherein a central portion in a longitudinal direction of an opening formed corresponding to a forming member and an inner peripheral side of the opening are formed in a shape that first comes into contact with the nozzle forming member. 2. The ink jet head according to claim 1, wherein the nozzle cover is warped such that a central portion in a longitudinal direction of the opening and an inner peripheral side of the opening protrude toward the head body. Ink jet head. 3. An ink jet head having a nozzle cover for covering a nozzle surface peripheral portion and a head side wall portion of a nozzle forming member having a plurality of nozzles, wherein the nozzle cover has an engaging claw portion projecting inward. An ink-jet head, wherein an engaging recess for engaging the engaging claw is formed in a side wall of the spacer member holding the head body, and a guide groove for guiding the engaging claw is formed. 4. The ink jet head according to claim 3, wherein the guide groove of the spacer member is formed to have a groove width narrowing toward a terminal side in a mounting direction. 5. The ink jet head according to claim 3, wherein a bending angle of the engaging claw of the nozzle cover with respect to an inner wall surface is set to 30 ° or less. 6. The ink jet head according to claim 3, wherein the engaging claw portion of the nozzle cover has a length and a width that require a force of 3 kg / f or less to be mounted on the head body. An ink jet head characterized by being formed. 7. The ink jet head according to claim 3, wherein a width of a plate for supporting the engaging claw portion of the nozzle cover is set to a half or more of a width of the claw portion. Inkjet head.