JPH09300633A - Ink-jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the electrical reliability in an ink-jet head by a method wherein the ink-jet head is equipped with a nozzle cover for covering the peripheral edge part of a nozzle forming member and the side wall part of a driving unit under the condition being joined with a flow path forming member. SOLUTION: A nozzle cover 4 is provided so as to cover the side wall part of a driving unit 1 and a liquid chamber unit 2. In addition, by joining the nozzle cover 4 with a flow path forming member 18, ink spreading in from the surface of a nozzle is completely shut off and consequently the electrical short-circuit between an EPC cable 34 and the electrode pattern 15 of a board 11 can be prevented from occurring. Further, when a vibrating plate 17 or a nozzle plate 19 is made of Ni, the joining strength between sealer and the plates is not enough, but enough joining strength is obtained by joining with the flow path forming member 18 made of photosensitive resin. Furthermore, an ink jet head consists of the driving unit 1, the liquid chamber unit 2, a head case 3 and the nozzle cover 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet head, and more particularly to an inkjet head having a nozzle cover and a head case.

[0002]

2. Description of the Related Art Since an ink jet recording apparatus has almost no vibration or noise during recording and it is particularly easy to color,
In addition to a printer that outputs data from a digital processing device such as a computer, it is also used for facsimile machines, copiers, and the like. An ink jet head used in such an ink jet recording apparatus records an image on a recording medium by ejecting ink droplets from nozzles by driving actuator elements such as a piezoelectric element and a heating resistor in accordance with a recording signal. It is what you do.

Due to the structure, such an ink jet head is of an edge shooter type in which ink droplets are ejected from the end face side of the stack of head constituent members, and a side shooter type in which circular nozzles are formed in the nozzle forming member. Can be roughly divided into As the ink jet head of the side shooter type, there is a conventional one, for example, Japanese Patent Laid-Open No. 6-25.
As described in Japanese Patent No. 5099, a flow path forming member that forms a flow path or the like pressurized by an actuator element is stacked on a drive unit having an actuator element housed in a head case, and the flow path is formed. It is known that a nozzle forming member in which a nozzle is formed is laminated on a member, and further has a nozzle protecting member 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. There is.

[0004]

By the way, in the ink jet head, when ink pools are formed on the nozzle surface, the flying direction of the ink droplets may be bent, which causes inconvenience. Therefore, the reliability maintaining mechanism wipes the nozzle surface. The ink is prevented from flowing out of the nozzle or dripping out of the ink, and the ink is not capped to prevent the ink from being dried and clogging the nozzle. . Moreover, since the characteristics of the nozzle surface affect the ejection characteristics of the ink droplets, a water repellent treatment is generally performed so that the ink does not easily adhere to the nozzle surface.

As a result, the nozzle surface of the ink jet head is always wet with ink. Especially, in the side shooter type ink jet head,
Ink that has flowed out of the nozzle surface easily penetrates into the drive unit that includes the actuator element, etc.If ink adheres to the electrical connection part of the drive unit, etc., a short circuit occurs and the actuator element cannot be driven, and ink drops cannot be ejected. Since it disappears, it is essential to block the ink flowing out from the nozzle surface.

In the above-described conventional side shooter type ink jet head, since the problem of blocking the ink flowing out from the nozzle surface is not taken into consideration, a nozzle protection member for covering the peripheral portion of the nozzle surface is provided. Although provided, the nozzle protection member is merely configured to be attached to the head case with an adhesive or mechanical fitting. Therefore, the ink flowing out from the gap between the nozzle surface and the nozzle protection member cannot be blocked, and the ink may permeate into the electrical connection portion, so that electrical reliability cannot be ensured.

The present invention has been made in view of the above points, and an object thereof is to ensure electrical reliability in an ink jet head.

[0008]

In order to solve the above-mentioned problems, an ink jet head according to a first aspect of the present invention comprises a nozzle forming member having a nozzle, and a flow path forming member forming a flow path communicating with the nozzle. In an inkjet head including a drive unit and a head case, the inkjet head includes a nozzle cover that covers a peripheral edge of the nozzle forming member and a side wall of the drive unit, and the nozzle cover is joined to the flow path forming member. It has a structure.

According to a second aspect of the present invention, there is provided the ink jet head according to the first aspect, wherein the side wall portions of the nozzle cover and the head case are provided with engaging means capable of engaging with each other.

According to a third aspect of the present invention, there is provided an ink jet head including a nozzle forming member having a nozzle, a flow passage forming member forming a flow passage communicating with the nozzle, a drive unit and a head case. The inkjet head includes a nozzle cover that covers a peripheral portion of the nozzle forming member and a side wall portion of the drive unit, and the side wall portion of the head case accommodates a transmission member that transmits an electric signal to each actuator element of the drive unit. The storage recess is provided.

[0011]

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 inkjet head to which the present invention is applied, and FIG. 2 is a cross-sectional view of a main part of the inkjet 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 is a liquid chamber unit in which a plurality of piezoelectric elements 12 are bonded and arranged in two rows on an insulating substrate 11 made of ceramic, glass epoxy resin or the like, and the piezoelectric elements 12 in each of these rows are surrounded and surrounded. Two
The frame 13 for supporting is joined. Also, the substrate 11
Above the common electrode pattern 14 and the individual electrode pattern 15
Is provided. In the common electrode pattern 14, the holes 16 provided in the frame 13 are filled with a conductive adhesive to establish continuity between the pattern portions.

The liquid chamber unit 2 includes a vibrating plate 17, a flow path forming member 18, and a nozzle plate 19 which is a nozzle forming member.
Are laminated and heat-bonded to each other. The diaphragm 17 includes a diaphragm 20 and a frame 3 which are displaced by the piezoelectric element 2.
Formed from a base 21 that is joined to the
Reference numeral 0 indicates a convex portion 22 and a thin film portion 23 that are bonded to the piezoelectric element 2.

The flow path forming member 18 is made of a photosensitive resin film having a two-layer structure, and includes a vibrating plate 17 and a nozzle plate 1.
9, a pressurized liquid chamber 25 facing the piezoelectric element 12, a common liquid chamber 26 located on both sides of the pressurized liquid chamber 25, and a pressurized liquid chamber 2
5 forms an ink supply path 27 that also serves as a fluid resistance portion that connects the common liquid chamber 26 and the common liquid chamber 26. 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 is composed of a PCB board 32 having a spacer 31 for holding the drive unit 1 and the liquid chamber unit 2, a head drive IC 33, etc., and the PCB board 32 and the piezoelectric element 12 of the drive unit 1. Are connected via the 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. The nozzle cover 4 is bonded to the flow path forming member 18 with a bonding agent 35 as shown in detail in FIG. This bonding is performed by applying the bonding agent 35 to the inner surface of the nozzle cover 4 by a dispenser in a region corresponding to the outer peripheral portion of the nozzle plate 19. As the bonding agent, a sealing agent that does not elute or swell with ink is suitable, and for example, an epoxy adhesive or a silicone sealing agent is suitable.

When the bonding agent 35 made of these sealing agents is applied to the inner surface of the nozzle cover 4 to a height of 0.2 to 0.3 mm, a part of the bonding agent permeates the interface between the nozzle plate 19 and the nozzle cover 4 and the nozzle cover 4 is covered. 4 forms a uniform film around the openings, and most of the other bonding agent 35 permeates in the thickness direction of the liquid chamber unit 2 to bond the flow path forming member 18 and the nozzle cover 4.

In this way, by joining the nozzle cover 4 and the flow path forming member 18, the ink that has permeated from the nozzle surface is completely cut off, and the electrical connection between the FPC cable 34 and the electrode pattern 15 of the substrate 11 is achieved. It is possible to prevent a physical short circuit. When the vibrating plate 17 and the nozzle plate 19 are made of Ni, the bonding strength with the sealant is not sufficient and they are bonded with the flow path forming member 18 made of a photosensitive resin (main component: acrylic resin). As a result, sufficient bonding strength can be obtained.

Further, as shown in FIGS. 1 and 3 (a), an inward cut / bend portion 36 serving as an engaging means is provided on the side portion of the nozzle cover 4, while the spacer 31 of the head case 3 is provided.
As shown in FIGS. 1 and 3 (b), a side wall portion is provided with a recess 37 with which the cut / bend portion 36 of the nozzle cover 4 engages.

With this structure, the nozzle cover 4
As shown in FIG. 3C, the cut / bent portion 36 of the nozzle cover 4 engages with the concave portion 37 of the spacer 31 of the head case 3 so that the nozzle plate 19 and the nozzle cover 4 are separated from each other. Even when a force is applied in the close contact direction to heat and cure the bonding agent 35, the bonding can be performed without using a pressing jig or the like. Then, when an external force is applied to the nozzle cover 4, even if the strength of only the bonding agent 35 is insufficient, the nozzle cover 4 does not float due to the mechanical coupling of the cut and bent portion 36 and the recess 37, and the reliability is improved.

Next, FIG. 4 is a perspective view of an essential part showing another embodiment of the present invention. In this embodiment, a storage recess 41 for housing the FPC cable 34 is provided by forming a protective wall 40 on the side wall end of the spacer 31 of the head case 3 of the above embodiment.

As a result, when the nozzle cover 4 is attached, the FPC cable 34 and the nozzle cover 4 come into contact with each other,
It is possible to prevent the FPC cable 34 from being damaged. That is, in the case where the storage recess 41 is not provided, when the FPC cable 34 is loose when the nozzle cover 4 is mounted as shown in FIG. 5, the FPC cable 34 and the nozzle cover 4 come into contact with each other, and the FPC cable 34. The FPC cable 34 and the electrode patterns 14 and 15 of the drive unit 1
There is a risk of peeling of the connection part with the.

In contrast, as in this embodiment, the FPC
By storing the cable 34 in the storage recess 41 of the spacer 31 and guiding the nozzle cover 4 with the protective walls 40, 40, the nozzle cover 4 can be smoothly mounted without coming into contact with the FPC cable 34, and the assembling is performed. In addition, the FPC cable 34 is prevented from being damaged and electrical reliability is improved. Furthermore, since the nozzle cover 4 is positioned by the protective wall 40, it can be assembled with high precision.

In the above embodiment, the present invention is applied to an ink jet head using a piezoelectric element as an actuator element, but the same applies to other ink jet heads using a heating resistor or the like as an actuator element. Can be applied.

[0025]

As described above, according to the ink jet head of the first aspect, the nozzle cover which covers the peripheral portion of the nozzle forming member and the side wall portion of the drive unit is provided, and the nozzle cover is joined to the flow path forming member. With this configuration, the ink on the nozzle surface is prevented from penetrating into the electrode joint portion, and the electrical reliability is improved. In addition, the joining force of the liquid chamber unit is reinforced.

According to a second aspect of the present invention, there is provided an ink jet head according to the first aspect, wherein the side wall portions of the nozzle cover and the head case are provided with engaging means capable of engaging with each other. Since the mechanical coupling means is also used, the adhesion between the nozzle cover and the nozzle forming member can be secured, and the resistance to external impact force can be improved, further improving the reliability.

According to the third aspect of the present invention, there is provided the nozzle cover which covers the peripheral portion of the nozzle forming member and the side wall portion of the drive unit, and the side wall portion of the head case sends an electric signal to each actuator element of the drive unit. Since the accommodation recess for accommodating the transmission member for transmission is provided, it is possible to prevent the electrical connection member from being damaged when the nozzle cover is attached, improve the electrical reliability, and assemble and assemble the nozzle cover. Accuracy is improved.

[Brief description of 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 a main part for explaining a nozzle cover and a head case of the inkjet head and an assembled state thereof.

FIG. 4 is a perspective view of an essential part showing another embodiment of the present invention.

FIG. 5 is an explanatory diagram for explaining the operation of the embodiment.

[Explanation of symbols]

1 ... Drive unit, 2 ... Liquid chamber unit, 3 ... Head case, 4 ... Nozzle cover, 11 ... Substrate, 12 ... Piezoelectric element,
13 ... Frame, 17 ... Vibration plate, 18 ... Flow path forming member,
19 ... Nozzle plate, 31 ... Spacer, 34 ... FPC
Cable, 35 ... Bonding agent, 36 ... Cut and bent portion, 37 ... Recessed portion, 41 ... Recessed recessed portion.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Iwase 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Shinyo Nakane 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Hideyuki Makita 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Tsutomu 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company

Claims (3)

[Claims] 1. An ink jet head comprising a nozzle forming member having a nozzle, a flow passage forming member forming a flow passage communicating with the nozzle, a drive unit and a head case, the ink jet head comprising the nozzle forming member. An inkjet head, comprising: a nozzle cover that covers a peripheral edge of a member and a side wall of the drive unit, the nozzle cover being joined to the flow path forming member. 2. The inkjet head according to claim 1, wherein the nozzle cover and the side wall portion of the head case are provided with engaging means capable of engaging with each other. 3. An ink jet head comprising a nozzle forming member having a nozzle, a flow passage forming member forming a flow passage communicating with the nozzle, a drive unit and a head case, the ink jet head comprising the nozzle forming member. A nozzle cover is provided to cover a peripheral edge of the member and a side wall of the drive unit, and a side wall of the head case has a storage recess for storing a member for transmitting an electric signal to each actuator element of the drive unit. Inkjet head characterized by.