JPS6337957A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To densify nozzles while holding the positional accuracy thereof without using special parts, by constituting the title recording head so that two head substrates each having a nozzle part and a flow passage forming part and having a specific outer shape of a specific dimension are formed on the surface of the same substrate in a superposed state. CONSTITUTION:The outer shape of each of head substrates 1 forms a line symmetric shape with respect to a center line (a) and a flow passage forming part consisting of a pressure chamber and a supply preparation chamber except the vicinity of a nozzle part is constituted so as to have an almost symmetric shape. Nozzles are formed so that the line (b) passing the center of the nozzle positioned at the central part is shifted by a distance 1/4 a nozzle interval T2 with respect to the center line (a) becoming a symmetric line at the leading end parts of nozzles arranged at an equal interval. Further, by assembling electrodes composed of metal plates, piezoelectric elements, wirings and a head cover, an ink jet head is constituted. That is, by superposing two head substrates in such a state the leading end parts of the nozzles are shifted by the distance 1/4 the interval of the nozzle with respect to the symmetric axis, the densification of the nozzles can be achieved easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an on-demand inkjet recording head having multiple nozzles, among inkjet recording heads that eject ink droplets to form an image on a recording medium. It is.

[Conventional technology]

Various recording heads of this type have been reported in which metal, glass, ceramic, or polymer resin is used as the base material of the head substrate. In order to increase the density of nozzles and channels on the same surface of a head substrate made of these base materials, there are constraints on the number of channels due to the space on the substrate surface, and manufacturing accuracy in minute parts such as nozzles. There is a limit due to the constraints of A method has been adopted to increase the density by arranging the nozzles parallel to each other and shifted by a distance of 1/2 the nozzle interval in the height direction.

[Problem that the invention attempts to solve]

The former method is complicated in terms of manufacturing, processing, and assembly, and may be impossible depending on the type of base material. In addition, there is a problem in that vibrations generated on one channel surface affect the other channel surface on the back side. On the other hand, the latter has problems such as it is difficult to achieve positional accuracy between the nozzles on the two-sided spatula substrate, and special methods and special members are required for this purpose.The purpose of the present invention is to The object of the present invention is to solve this problem and easily increase the nozzle density while maintaining nozzle position accuracy without using special parts.

[Means for resolving the gap]

The inkjet recording head of the present invention is composed of two head substrates each having a nozzle portion, a flow path forming portion, and an external shape having characteristics in size and shape, and these are overlapped on the same substrate surface. Example] Hereinafter, embodiments of the present invention will be explained based on the drawings. Figures 1 (a") and e) show an embodiment of the present invention, and Figure 1 (α) shows an example of plastic injection. The head substrate 1 is molded and made of ceramic, etc., and a pressure chamber 2, a nozzle 3, and a supply preparation chamber 4 are formed on the substrate 1.Here, the external shape of the head substrate is as shown in the figure. center line a
The pressure chamber and the supply preparation chamber, excluding the vicinity of the nozzle part, are also line-symmetrical with respect to the center line. On the other hand, for the tips of nozzles lined up at equal intervals, I! passes through the center of the nozzle located in the center! ! 6 is formed to be shifted by a distance of 1/4 of the nozzle interval T2 with respect to the center line α, which is the axis of symmetry. That is, in the figure, TI and T2 are TI =
It is configured to be 1/4·T2. and,
An actual ink flow path is formed by bonding the head substrate K and the diaphragm 5 together. Furthermore, the inkjet head is constructed by assembling electrodes 6 made of metal plates or metal films, piezoelectric elements 7, wiring 8, head cover 9, and the like.

FIG. 2 shows an inkjet recording head that has a high density by combining the two heads described above.

When two heads are placed on top of each other with the non-grooved surfaces of the head substrates, the outer peripheries of the heads coincide because their outer shapes are symmetrical with respect to the center line. On the other hand, at the nozzle tip, 1iI6, which passes through the center of the nozzle located in the center, is shifted from the symmetry axis α by a distance of 1/4 of the nozzle interval T2. The nozzle of the other overlapping head is positioned at the center position between them. This makes it possible to double the nozzle integration density.

Since the two heads have the same external shape when placed one on top of the other, they can be easily fixed and positioned by the holder 10.11.

As another example, in order to accurately position and fix two heads, as shown in FIG. By providing a hole 12 and fixing the two heads by passing a metal pin 13 of a simple shape for the purpose of positioning into the hole that matches when the two head boards are stacked one on top of the other. This is easily possible.◎ Also, as shown in Figure 4, on the overlapping surface of the head substrate, there are cylindrical protrusions on one side at two locations symmetrical to the center line near the nozzle part. At the other position of the portion 14, a blind hole or a through hole opening 11s15 of the same shape is provided with dimensions that take into consideration the pressure margin against the projection.

By aligning and fixing these uneven portions of the two heads, it is possible to easily and accurately position the two nozzle portions.

〔Effect of the invention〕

As can be seen from the above description, according to the present invention, by giving the head substrate a shape characteristic, that is, the outer shape is symmetrical, and the nozzle tips are 1/1/2 of the nozzle spacing with respect to the axis of symmetry. Since the two head substrates are deviated by a distance of 4, it is possible to easily achieve high nozzle density by overlapping the two head substrates.

In addition, in order to increase the nozzle density by overlapping two independent heads, there is a problem with the problem of increasing the density by forming nozzles and flow channels on both sides of the head substrate. There is no problem with the influence of vibrations generated in the pressure chamber on the other side.

Furthermore, according to the present invention, the head 2 is made of a head substrate.
Compared to the method of increasing density by arranging the nozzles parallel to the horizontal direction and staggered by 1/2 of the nozzle spacing in the height direction, this method is easier and requires special methods and special parts. It is possible to position the nozzle without any trouble. 2
The distance between the nozzles of the two heads can also be kept as small as possible, which has the effect of making the head smaller and reducing the data memory during printing.In addition, the external shape must be symmetrical. Since the flow path except for the vicinity of the nozzle part is also approximately symmetrical, flow path design and manufacturing of the head substrate are facilitated, and variations in characteristics between nozzles are also reduced.Furthermore, the method according to the present invention , it is composed of two structurally independent heads, and by supplying different types of ink to each head, it is also possible to apply it to a color inkjet head.

[Brief explanation of the drawing]

FIG. 1(a) is a diagram showing a head substrate constituting the inkjet recording head of the present invention, and FIG. 1(b) is a perspective view showing the configuration of one inkjet head. , Figures 3 and 4 are perspective views of an inkjet recording head that combines two heads to achieve high density.
@1: Head substrate 2: Perspective views of inkjet heads showing other embodiments of the present invention, respectively.
Pressure chamber 3... Nozzle 4... Supply preparation chamber 5
...Vibration plate 6...Metal plate 7...Piezoelectric element 8...Wiring 9...Head cover 10.11...Holder 12...Through hole 13...
・Positioning pin 14... Convex portion 15... Concave portion or more Applicant Seiko Epson Co., Ltd. Agent Patent attorney Mogami, Tsutomu and 1 other person, ,' , (α) (b) Go to Figure 1 1゛・Y-do basic phase, Figure 2, Figure 3, Figure 4! , °to, 9 do 1 Kengawara

Claims (1)

[Claims] A head substrate in which the external shape and the flow path forming part excluding the nozzle tip and its vicinity are line symmetrical, and the nozzle tip is formed to be shifted by a distance of 1/4 of the nozzle interval with respect to the axis of symmetry. With two inkjet heads,
An inkjet recording head characterized in that the inkjet recording head is constructed by overlapping them on the same substrate surface.