JPH0624854B2 - Ink jet head - Google Patents

Description

The present invention relates to the structure of an inkjet head used in a facsimile, a printer, or the like.

[Conventional technology]

The ing jet recording technique is a technique for ejecting ink from a fine nozzle toward a recording medium to perform recording, and attempts have been made for practical use for many years. As an inkjet head used for this inkjet recording, there are a continuous jet type and an on-demand type. The on-demand type ejects inking droplets only when necessary, and is characterized by not requiring an ink recovery mechanism or ink droplet deflection.

In the conventional structure of such an on-demand type head, as shown in FIG. 3, for example, a cylindrical glass tube 200 is extended to form a nozzle 201 and a pressure chamber 202, and a cylindrical piezo 203 is arranged outside the pressure chamber. It is stuck.
Further, in order to connect the pressure chamber 202 and the pipe 205, a joint 204 is fixed to the end surface of the glass tube 200 opposite to the nozzle 201 and connected to the pipe 205. Although this conventional inkjet head has a simple structure, it has a drawback that the repetition frequency of the droplet ejection is up to about 5 kHz, and if the repetition frequency is higher than this, the fluctuation of the droplet speed becomes severe.

Therefore, there is a need for a high-performance ink jet that suppresses the speed fluctuation at such a high repetition frequency. Such an inkjet head is disclosed in Japanese Patent Application No. 58-159820.
It is disclosed in Japanese Utility Model Application No. 57-017589.

An example of such an inkjet head is shown in FIG. A nozzle part 300 having a conical connection flange having a hole diameter of several tens of μm at the tip part, and a fluid resistance element having a large number of fine holes in a disk-shaped thin plate contained in a predetermined disk-shaped housing. A resistor portion 301, a piezoelectric element component 302 in which a piezoelectric element is reinforced with an adhesive, a valve component 303 in which a fine valve element including a disc-shaped valve seat and a valve is housed in a disc-shaped housing, and piping. Joints 304 for connection of
And is connected to the pipe 205. These parts are hermetically connected by an adhesive. By thus inserting the valve element or the fluid resistance element at a predetermined position, there is obtained an ink jet head in which the drop velocity does not fluctuate with respect to the high return frequency and the drop size can be modulated.

[Problems to be solved by the invention]

However, in an ink jet head that incorporates these valve element and fluid resistance element to improve performance, the nozzle section,
Since it is divided into a fluid resistance element part, a piezoelectric element part, a valve element part, a joint, etc., it is necessary to hermetically connect these parts. Actually, an adhesive is applied to the end faces of each part and the parts are pasted together to meet the above requirements. Meet

However, in such a method of connecting the respective parts, firstly, a complicated process of uniformly applying a fixed amount of the adhesive to the minute parts is required, and secondly, the individual parts to which the adhesive is applied are connected. In this case, careful handling is required, thirdly it takes time to dry the adhesive, and fourthly, even when assembled with the utmost care, the adhesive may flow into the ink passages. There was a problem such as a decrease in yield.

An object of the present invention is to solve these problems and to provide a structure of an inkjet head which has high performance, is easy to assemble, and has a high yield.

[Means for solving problems]

The configuration of the present invention includes a nozzle that ejects minute ink droplets,
The fluid resistance element for adjusting the flow rate of the ink fluid, the electro-mechanical conversion element for applying pressure to the fluid, the valve element for controlling the flow rate of the fluid, and the piping for inputting the fluid are connected. In an inkjet head including a joint, each of the components has a housing portion fixed to a housing having an O-ring groove on one surface to be connected, and each housing portion and the joint have one end. Are arranged in a predetermined order in a box-shaped housing having a stopper for the nozzle and a pressing means for pressing the other end, and O-rings are inserted in the O-ring grooves between the housing parts. When the pressure is applied by the pressing means, it is hermetically integrated.

〔Example〕

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

FIGS. 1 (a) and 1 (b) are partially exploded exploded perspective views and side sectional views of an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are configurations of the fluid resistance component 104 of FIG. It is a perspective view and a sectional view of an article. In this embodiment, the stoppers 101 and 11 are provided at both ends.
2 into the groove 100 of the housing 115 with the nozzle part 10
3, the fluid resistance component 104, the piezoelectric element component 108, the valve component 109, and the joint 110 are respectively inserted through the O-ring 114, and the screw 1 is inserted from one stopper 112 side.
It is configured to be pressed by 13. The other stopper 101
A cone nozzle (103) penetrates through the hole, and a hole 102 is formed so as to be supported by a flange on the bottom side of the cone nozzle. The nozzle component 103 is composed of a conical nozzle body, a housing that also functions as a reinforcement, a flange, and a positioning for the nozzle.
It is arranged so that it penetrates through and is fixed by a flange. This conical nozzle is formed on a master mold that is precisely pressed, mainly by using photolithography technology or plating technology.

As shown in FIG. 2, the fluid resistance component 104 stores the fluid resistance element in a rectangular parallelepiped housing 105 having a through hole 120 in the center and an O-ring groove 106 on one surface and a width equal to the width of the groove 100. Formed. A minute O-ring 114 is housed in the O-ring groove 106 and arranged so that the O-ring side is the nozzle side. By using such a housing 105, it is possible to seal the ink passage of each component and position the passage. The depth of the O-ring groove 106 is preferably equal to or larger than the radius of the O-ring 114. A large number of fluid resistance elements are formed on a substrate such as ceramic or glass by using vapor deposition, photolithography, plating technology, etc., and a hole of several μ is formed in a disk with a diameter of several mm and a film thickness of + μ. Are formed in large numbers. Next, each of the piezoelectric element components 108 is formed by fixing the housing 105 to both ends of the cylindrical piezoelectric element 107, and the surfaces of the housings at both ends in which the O-rings 114 are housed are the fluid resistance component 104 and the valve component 109, respectively. It is arranged to face. Like the fluid resistance element, the valve component 109 is arranged such that the surface in which the valve element is housed in the housing 105 and houses the O-ring faces the joint 110 side. The valve element is formed in a large amount on a substrate such as ceramic or glass by vapor deposition, photolithography, etching, and plating technology, and is composed of a disk-shaped valve and valve seat having a thickness of several 10 μm and a diameter of several mm. .

Further, the joint 110 is formed so that a hole is dug in one surface of a rectangular parallelepiped metal or an insulator and penetrates at a right angle to the hole dug from the other surface.
9 and the other surface is a joint 111 for connection with the pipe.
Is added so that it faces upward.

The components arranged in this manner are pressed by screws 113 provided on the stopper 112 side of the housing 115 to crush the O-rings 114 housed in the grooves between the components.
Pressing is applied until the surfaces of adjacent housings come into close contact. Therefore, it is preferable that both surfaces of the housing are smooth surfaces, and it is necessary to remove burrs during pressurization. It should be noted that the O used to seal between each part
Although the ring 114 is not obtained by a normal standard product, a ring finely manufactured according to the size of each minute component of the inkjet head is used.

As described above, in the inkjet head of this embodiment,
Since a fine O-ring is crushed during assembly to enable hermetic integration, there is no need to use an adhesive. Therefore, there is no need for a quantitative and uniform application process of the adhesive to the minute parts, there is no need to handle the minute parts coated with the adhesive, and a process for drying the adhesive is also unnecessary. There are no accidents due to the inflow.

In the above embodiments, the case and the groove are mainly rectangular. However, a structure using a disk-shaped housing in a hollow cylinder having a circular or polygonal shape and a stopper at the tip is used for dropping parts. It is also possible to consider such things. Further, although the joint 110 has been described in which the ink passage in the head and the pipe are connected at a right angle, for example, the ink passage and the pipe are easily aligned in the axial direction by making the screw used for obtaining the pressing pressure hollow. The structure is also conceivable. Further, the present invention can be sufficiently applied to an inkjet head having no valve element or fluid resistance element, or an inkjet head having only a valve element or a fluid resistance element.

〔The invention's effect〕

As described above, the ink jet head according to the present invention incorporates a valve element, a resistance element, and the like, maintains high performance characteristics such that the droplet speed fluctuation is small and the droplet size can be modulated, and the inter-component Since the structure is such that the sealing and loosening can be easily realized by using a fine O-ring and pressing pressure without using an adhesive, the step of uniformly applying the adhesive to the minute parts is not necessary, and the minute parts coated with the adhesive are unnecessary. Does not need to be handled, and the step of drying the adhesive is not necessary, and defects are eliminated by the flow of the adhesive into the ink passage, which has a great effect on the improvement of cost, reliability, and yield. Further, even if there are some component defects, rubber, etc., they can be easily disassembled, so that defective components can be easily replaced, and the overall yield is improved.

[Brief description of drawings]

1 (a) and 1 (b) are partially fragmented exploded perspective views and side sectional views of one embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are each a fluid resistance component 104 used in this embodiment. FIG. 3 is a perspective view and a sectional view of a housing of the device, FIG. 3 is a sectional view of a conventional simple inkjet head, and FIG. 4 is a side view of a conventional high-performance inkjet head. 100 ... Groove, 101, 112 ... Stopper, 102
... hole, 103 ... nozzle part, 104 ... fluid resistance part, 105 ... housing, 106 ... O-ring groove,
107 ... Piezoelectric element, 108 ... Piezoelectric element component, 109
…… Valve parts, 110 …… Joints, 111 …… Connection joints, 113 …… Screws, 114 …… O rings, 11
5 ... Casing, 200 ... Glass tube, 201 ... Nozzle,
202 ... Pressure chamber, 203 ... Cylindrical piezo, 204, 3
04 ... Joint, 205 ... Piping, 300 ... Nozzle section, 301 ... Fluid resistance element section, 302 ... Piezoelectric element section, 303 ... Valve element section.

Claims (1)

[Claims] 1. A nozzle for ejecting minute ink droplets, a fluid resistance element for adjusting the flow rate of ink fluid, an electro-mechanical conversion element for applying pressure to the fluid, and a valve element for controlling the flow rate of the fluid. In the ink-jet head, which comprises a joint for connecting each component and a pipe for inputting the fluid, each component has a housing portion fixed to a housing having an O-ring groove on one surface to be connected. The respective housing portions and the joint are arranged in a predetermined order in a box-shaped housing having a stopper for the nozzle at one end and a pressing means for pressing at the other end. Between said O
An inkjet head, wherein an O-ring is inserted into each ring groove and is hermetically integrated when pressed by the pressing means.