JPH066373B2 - Ink jet head - Google Patents

Description

The present invention relates to an inkjet head, and more particularly to an inkjet head used in an inkjet recording type facsimile, printer, or the like.

[Conventional technology]

The inkjet recording method is a recording method in which ink is ejected from a fine nozzle toward a recording medium to perform recording, and an inkjet head used in this inkjet recording method includes a continuous ejection type and an on-demand type. The on-demand type is widely used because it ejects ink droplets when necessary and does not require ink recovery or ink droplet deflection.

An example of a conventional on-demand type ink jet head (hereinafter referred to as a first conventional example) is, as shown in FIG. 3, extending a cylindrical glass tube 301 to form a nozzle 302 and a pressure chamber 303. A structure in which a cylindrical piezo 304 is arranged and fixed on the outside of 303. Further, in order to connect the pressure chamber 303 and the pipe 305, the glass tube 30
A joint 306 is fixed to the opposite side of the first nozzle 302. Although this first conventional example has a simple structure, it has a drawback in that if the repetition frequency of the droplet ejection exceeds about 5 kHz, the variation of the droplet velocity becomes severe and it cannot be used.

Along with the demand for higher recording speed, there has been a demand for a high-performance inkjet head that suppresses the fluctuation of the drop speed at such a high repetition frequency. Such an ink jet head is disclosed in Japanese Patent Application No. Sho 58-159820 and Japanese Patent Application No. Sho 57-017589.
Etc.

An example of such an ink jet head (hereinafter referred to as a second conventional example) is shown in FIG. In this second conventional example, a conical nozzle portion 307 having a hole having a hole diameter of several tens of microns at the tip and a connecting flange at the bottom, and a fluid resistance having a large number of fine holes in a disk-shaped thin plate are used. A fluid resistance portion 308 in which an element is housed in a predetermined disc-shaped housing, a piezoelectric element portion 309 in which a piezoelectric element is reinforced with an adhesive or the like, and a fine valve element including a disc-shaped valve seat and a valve are circular. The valve element unit 310 housed in a plate-shaped housing and a joint 312 for connecting to the pipe 311 are provided and connected to the pipe 311. These parts are sealed and continuous with each other by an adhesive, and in particular, by inserting the valve element and the fluid resistance element at a predetermined position, the drop speed does not fluctuate at a high repetition frequency, and the size of the drop is reduced. An inkjet head capable of modulation has been obtained.

However, the inkjet head is required to be mounted at a high density, and therefore each component is formed finely. Therefore, using an adhesive for assembling such a fine component requires a lot of man-hours and costs. Get high Furthermore, when the components are bonded together, the adhesive penetrates into the fluid passages inside the components, which causes a problem that the performance as an inkjet head cannot be obtained.

In order to reduce the number of man-hours for such a problem, there is an ink jet head (hereinafter referred to as a third conventional example) described in Japanese Patent Application No. 61-056168 shown in FIG. In FIG. 5, a housing 315 having stoppers 313 and 314 at both ends.
The groove 316 of the nozzle part 317, the fluid resistance part 31
8, piezoelectric element component 319, valve component 320, joint 3
21 are fixed to each other, and an O-ring 322 is sandwiched between the boundaries of the respective parts. Each part and O-ring 32
2 is pressed by the screw 323 of the stopper 314 to be hermetically integrated.

[Problems to be Solved by the Invention] In an inkjet head, it is necessary that the internal fluid path from the nozzle to the joint is sealed against the outside air, and the sealing ensures performance and improves reliability. At the same time, it is important to reduce man-hours and cost at the time of assembling the head. However, in the third conventional example in which the O-ring 322 is inserted, the O-ring 322 is required due to the requirement of high-density mounting. Requires a very special small shape, which leads to cost increase in terms of component price.

Further, since the O-ring 322 is used in large numbers, a particularly small O-ring 322 is inserted into each component at the time of assembly, so that workability is extremely poor. Further, the O-ring 322 is not properly inserted at the time of insertion and sticks out from the O-ring groove, which causes a problem that the hermeticity at the boundary of each component is not obtained. Furthermore, when each component is placed in the groove of the housing, even if the groove serves as a guide for the component, if the shape of the groove and each component is not accurate, there will be a gap between the components when pressing and assembling. There is also a problem that the hermeticity cannot be obtained. That is, the use of the O-ring requires a great number of assembly steps, which leads to an increase in cost, and there is a problem that automation required for mass production is also difficult.

An object of the present invention is to provide an inkjet head that solves these problems.

[Means for solving problems]

The inkjet head of the present invention controls a nozzle for ejecting a minute ink droplet, a fluid resistance element for adjusting a flow rate of the ink, an electromechanical conversion element for applying a pressure to the ink, and an inflow / stop of the ink. An ink jet head having a valve element for connecting the ink and a joint to which a pipe for inflowing the ink is connected, and at least one end of the electromechanical conversion element, the nozzle, the fluid resistance element, or the valve. A plurality of housings having a recess into which any one of the elements is inserted; and a housing having stoppers and pressing means facing each other across a space, the plurality of housings, the nozzle, and the fluid resistance element, and The electromechanical conversion element, the valve element, and the joint are predetermined in the space. Sequentially arranged, pressurized by the pressing means, and the projection in which the housing, the stopper, or the joint that is in contact with the recess is fitted in the recess in which the nozzle, the fluid resistance element, or the valve element is inserted is fitted. Consists of

[Action]

One end of the electromechanical conversion element or each housing and joint in which the nozzle or the fluid resistance element or the valve element is inserted in the recess is arranged in a predetermined order in the space between the stopper of the housing and the pressing means, and is pressed by the pressing means. A protrusion provided on a housing, a stopper, or a joint that is in contact with the recess is fitted into the recess into which the nozzle, the fluid resistance element, or the valve element is inserted.
The nozzle, the fluid resistance element, and the valve element are pressed into contact with and fixed to the bottom surface of the recess into which the nozzle is inserted and the tip of the protrusion that is fitted into the recess, and are also connected to each other by the interference fit. The housing or stoppers or joints are hermetically integrated and positioned by an interference fit without the use of adhesives or O-rings.

〔Example〕

 The present invention will be described in detail with reference to the drawings.

FIG. 1 (a) is a sectional view showing a first embodiment of an ink jet head of the present invention, and FIG. 1 (b) is a sectional view of a housing into which a fluid resistance element is inserted in this embodiment.

In the embodiment shown in FIG. 1 (a), stoppers 10 are provided at both ends.
A groove 104 is provided in a housing 103 having the nozzles 1 and 102, and a nozzle housing 105 and a nozzle 10 are provided in the groove 104.
6, fluid resistance element 107, housing 1 for fluid resistance element
08, piezoelectric element 109, housing 1 for two piezoelectric elements
10, the valve element 111, the valve element housing 112, and the joint 113 are inserted. The nozzle 106, the liquid resistance element 107, and the valve element 111 are formed by a photolithography technique, a plating technique, or etching.

The nozzle 106 is inserted into the nozzle housing 105 which has a through hole for allowing the conical nozzle 106 to pass therethrough and has a recess for inserting the nozzle 106 at one end surface. The other end surface of the nozzle housing 105 is the housing 10.
3 is in contact with one of the stoppers 101, and the nozzle 106
Are arranged so as to penetrate the hole 114 of the stopper 101. The fluid resistance element 107 has a recess 115 (FIG. 1) at one end.
(See (b)). The fluid resistance element housing 108 has a protrusion 116 at the other end, is coupled to the recess of the nozzle housing 105 by an interference fit, and fixes the nozzle 106 so as to sandwich it. Further, the fluid resistance element housing 108 is provided with a through hole 117 as a fluid path.

The piezoelectric element 109 forms a hollow cylinder, and both ends thereof are inserted into two piezoelectric element housings 110. Each of the piezoelectric element housings 110 has a protrusion and a recess formed at both ends. One of the protrusions of the piezoelectric element housing 110 is inserted into the recess 115 of the fluid resistance element housing 108 to fix the fluid resistance element 107 so as to sandwich it. Further, the piezoelectric element 109 is inserted into and fixed to the recesses of the two piezoelectric element housings 110 via a fastening material 118 made of a hard material such as fluororubber. The other piezoelectric element housing 110 is connected to the valve element housing 112. Valve element housing 112
Has the same shape as the fluid resistance element housing 108, and the valve element 111 is fixed by being sandwiched between the protrusion of the piezoelectric element housing 110 and the recess of the valve element housing 112. The joint 113 having the pipe 119 is provided with a recess at one end so as to correspond to the protrusion of the valve element housing 112. In addition, the joint 113 is the housing 10.
It is pressed by a screw 120 provided on the other stopper 102 of No. 3. The screw 120 is formed hollow so that the pipe 119 of the joint 113 can be inserted therethrough.

The respective element parts and the housing are pressed by the screws 120, and due to the interference fit, the parts are hermetically integrated without any displacement. Each of these parts, particularly each housing, can be formed of a composite material such as plastic, and can be mass-produced with high precision by injection molding or the like. In addition, the groove 104 of the housing 103
By simply inserting and pressing each component into the, it is possible to assemble in a short time without using a jig for assembling, and it is possible to automate component insertion and screwing, and mass production is possible. Furthermore, since each part is joined by a tight fit at the recesses and protrusions, there is no positional deviation between parts, that is, there is no deviation in the fluid path, a stable flow path is formed, and reliable output of ink droplets is possible. It will be possible.

FIG. 2 is a sectional view showing a second embodiment of the ink jet head of the present invention.

In the embodiment shown in FIG. 2, the nozzle 106, the nozzle housing 105, the fluid resistance element 107, the fluid resistance element housing 108, the piezoelectric element 109, the fastening member 118,
The two piezoelectric element housings 110, valve elements 111, valve element housings 112, and joints 113 are inserted into a hollow cylindrical housing 121. The nozzle housing 105 is fixed to one end surface of the housing 121, and the nozzle 1
A stopper 122 having a hole 114 penetrating through 06 is provided. A screw 124 as a pressing means is provided on the stopper 123 at the other end to press the housings and the element parts. The piezoelectric element 10 is provided on a part of the side surface of the housing 121.
Window 126 for taking out lead wire 125 taken out from
Is provided.

It is the same as in the first embodiment that the housings are pressed by the screws 124 to fix the respective element parts and are hermetically integrated by the interference fit. Since the components can be assembled simply by dropping the respective parts into the hollow cylindrical casing 121 and tightening them, a reliable head can be obtained with a small number of steps as in the first embodiment.

It is also possible to provide recesses at both ends of the housing and insert the two element parts into the respective recesses. For example,
In the first embodiment, a housing in which one end of the piezoelectric element 109 and the valve element 111 are inserted into the recesses at both ends is used, and the protrusion provided on the joint is fitted into one of the recesses to fix the valve element 111. You can

The present invention is effective in a structure in which a protruding portion and a concave portion for receiving the protruding portion and fixing each element component are formed at the boundary of the housing, and are pressed and tightly fitted.

〔The invention's effect〕

As described above, the inkjet head of the present invention is
Insert the housing with the recess for inserting and fixing each element component that constitutes the inkjet head into the housing,
By pressing and fitting the protrusions provided on the adjacent housing etc. into the recesses, the structure is hermetically integrated, so the assembly man-hours are greatly reduced and the cost is reduced. Since it is precisely and tightly integrated with the projections that are fitted into it, there is an effect that stable operation is possible and reliability is high.

[Brief description of drawings]

FIG. 1 (a) is a sectional view showing a first embodiment of an inkjet head of the present invention, FIG. 1 (b) is a sectional view of a fluid resistance element housing used in this embodiment, and FIG. FIG. 3 is a cross-sectional view showing a second embodiment of the conventional inkjet head, FIG. 3 is a cross-sectional view of the first conventional inkjet head, and FIG. 4 is a side view of the second conventional inkjet head. The figure is a cross-sectional view of a third example of a conventional inkjet head. 101, 102, 122, 123 ... Stopper, 10
3, 121 ... Housing, 104 ... Groove, 105 ... Nozzle housing, 106 ... Nozzle, 107 ... Fluid resistance element, 108 ... Fluid resistance element housing, 109 ...
... Piezoelectric element, 110 ... Housing for piezoelectric element, 111
... Valve element, 112 ... Valve element housing, 113 ...
… Joints, 114 …… holes, 115 …… recesses, 116
...... Protrusions 117 ...... Through holes 118 ...... Tightening materials 1
19 ... pipe, 120,124 ... screw, 125 ...
Lead wire, 126 ... Window.

Claims (1)

[Claims] 1. A nozzle for ejecting minute ink droplets, a fluid resistance element for adjusting the flow rate of the ink, an electromechanical conversion element for applying pressure to the ink, and a valve for controlling the inflow / stop of the electric ink. In an inkjet head provided with an element and a joint to which a pipe for inflowing the ink is connected, at least one end of each of the electromechanical conversion element or the nozzle or the fluid resistance element or the valve element A plurality of housings having recesses into which any one of them is inserted, and a housing having stoppers and pressing means facing each other across a space, and the plurality of housings, the nozzles, the fluid resistance elements, and the electrical components. The mechanical conversion element, the valve element, and the joint are arranged in the space in a predetermined order and the push It is characterized in that it is pressurized by a pressurizing means, and a protrusion provided on the housing, the stopper, or the joint in contact with the recess is fitted into the recess into which the nozzle, the fluid resistance element or the valve element is inserted. And inkjet head.