JPH0733085B2 - Inkjet head - Google Patents

Description

TECHNICAL FIELD The present invention relates to an inkjet head in an inkjet recording apparatus, and more particularly to improvement of an ink-on-demand type inkjet head.

[Prior Art] FIG. 4 is a cross-sectional view schematically illustrating an example of a conventional ink-on-demand type inkjet head. In this figure, the left end of the rod-shaped piezoelectric body 2 is fixed to the left end of the support block 1. A pressure chamber block 3 is fixed to the right end of the support block 1. The pressure chamber block 3 includes a pressure chamber 4, and the right end of the rod-shaped piezoelectric body 2 is inserted from the left end of the pressure chamber 4 in a liquid-tight and slidable manner. The right end of the pressure chamber 4 is closed by a nozzle plate 6 including a nozzle 5. Further, the pressure chamber 4 communicates with an ink supply hole 7 for supplying ink from an ink source (not shown). The rod-shaped piezoelectric body 2 has a pair of electrodes 8
Are provided, and their electrodes 8 are connected to the recording signal voltage source Vs.
It is connected to the. In the ink jet head configured as described above, when a recording signal is applied from the recording signal voltage source Vs to the pair of electrodes 8, the rod-shaped piezoelectric body 2 is slightly lengthened due to the lateral effect. Therefore, the rod-shaped piezoelectric body 2 pressurizes the ink in the pressure chamber 4, and the ink droplet is ejected from the nozzle 5.

[Problems to be Solved by the Invention] In the conventional inkjet head shown in FIG. 4, the rod-shaped piezoelectric body 2 has a length of about 10 to 20 mm so as to cause a required extension depending on the applied recording signal voltage. Must have a length. On the other hand, in order to reduce the size of the inkjet head, it is desired that the rod-shaped piezoelectric body 2 be thin. In particular, in an inkjet head having a multi-nozzle, a plurality of rod-shaped piezoelectric bodies corresponding to the number of nozzles are juxtaposed, so that it is desirable to make the rod-shaped piezoelectric bodies 2 thinner. However, the thinness of the rod-shaped piezoelectric body 2 is limited from the viewpoint of its mechanical strength. Therefore, miniaturization of the inkjet head is restricted by the thickness of the rod-shaped piezoelectric body, and the restriction is remarkable especially in the multi-nozzle head.

Further, in the past, when a multi-nozzle head was constructed,
A plurality of inkjet heads as shown in the drawing are arranged side by side. That is, the individual inkjet heads forming the multi-nozzle head are individually assembled. Therefore, the conventional multi-nozzle head assembly process is complicated, and the ink ejection characteristics must be adjusted between individual inkjets.

In view of the above problems of the prior art, the object of the present invention is to
An object of the present invention is to provide a multi-nozzle head that is easy to assemble and has a small size.

[Means for Solving the Problems] An inkjet head according to the present invention includes a comb-shaped piezoelectric body including a guide member including a plurality of elongated cylinders and a plurality of elongated branches inserted from the first ends of the plurality of cylinders. A plurality of pressure chambers formed between the second ends of the plurality of cylinders and the tips of the inserted branches, and a plurality of ink supply holes for supplying ink to the plurality of pressure chambers. , A plurality of nozzles for ejecting ink droplets from a plurality of pressure chambers, and a plurality of sets of electrodes provided for each branch of the piezoelectric body, and each of the plurality of cylinders has a plurality of branches of the piezoelectric body. Each of the branches is mechanically protected by enclosing the main length of each of them, and when a recording signal voltage is applied to a selected set of a plurality of sets of electrodes, the branch of the corresponding piezoelectric body is The tip is displaced, which causes an ink drop to be ejected from the corresponding nozzle.

[Operation] In the multi-nozzle head according to the present invention, the piezoelectric body is integrally formed in a comb shape including a plurality of elongated branches, and the guide member includes the main length of each of the plurality of branches of the piezoelectric body and is mechanically formed. Includes multiple elongate tubes to protect. Therefore, since each branch of the piezoelectric body can be thinned, not only the multi-nozzle head can be downsized, but also its assembly can be facilitated.

[Embodiment] FIGS. 1A and 1B are diagrams for schematically explaining the structure of an inkjet head of the present invention, and are a cross-sectional view and a partially enlarged view thereof, respectively. With reference to these figures, an elongated rod-shaped piezoelectric body 2a is inserted in the groove of the pressure chamber base 31a, the left end of the rod-shaped piezoelectric body 2a is fixed to the left end of the pressure chamber base 31a. There is. Piezoelectric rod 2
A pair of electrodes 8a is provided on a, and the piezoelectric body and the electrodes are covered with a seal film 9. A nozzle member 6a including a nozzle 5a is fixed to the left end of the pressure chamber base 31a. The right end of the rod-shaped piezoelectric body 2a and the nozzle member 6a
The pressure chamber 4a is formed between the pressure chamber 4a and the pressure chamber 4a, and the pressure chamber base 31a is covered by the pressure chamber cover plate 32a. The pressure chamber cover plate 32a includes an ink supply hole 7a for supplying ink to the pressure chamber 4a. Pressure chamber cover plate 32
An ink tube fixing plate 33a for fixing the ink tube 10 is further fixed on a. The ink tube 10 guides ink from an ink source (not shown) to the ink supply hole.

The seal film 9 improves the liquid tightness of the pressure chamber 4a and the slidability of the rod-shaped piezoelectric body 2a. Furthermore, when the pressure chamber base 31a and the pressure chamber cover plate 32a are made of a metal material, the seal film 9 is used for the pressure chamber parts 31 of those members.
It also acts as an insulating material between a and 32a and the electrode 8a.

It will be appreciated that an inkjet head constructed in this manner can operate similarly to the conventional inkjet head shown in FIG. However, in the inkjet head of FIG. 1A, most of the length of the rod-shaped piezoelectric body 2a is contained in the elongated cylinder formed by the groove of the pressure chamber base 31a and the pressure chamber cover plate 32a. Therefore, the rod-shaped piezoelectric body 2a is mechanically protected by the cylinder, and can be made much thinner than the conventional rod-shaped piezoelectric body 2. As a result, the inkjet head of FIG. 1A can be made smaller than the conventional inkjet head. In particular, when a multi-nozzle head is constructed by using an inkjet head as shown in FIG. 1A, the effect of downsizing becomes more remarkable. Now, FIG. 1A shows a cross section of such a multi-nozzle head. Then, FIG. 1C shows a part of the cross section along the line 1C-1C in FIG. 1A. That is, when a multi-nozzle head is configured, since a plurality of rod-shaped piezoelectric bodies 2a are juxtaposed, even if the thickness of each rod-shaped piezoelectric body is slightly reduced, the size of the multi-nozzle head is reduced as a whole. It will be understood that it can make a significant contribution to

By mechanically protecting the rod-shaped piezoelectric body with the pressure chamber base and the pressure chamber cover plate in this manner, it is possible to reduce the size of the inkjet head as compared with the conventional one.
Since it is necessary to individually insert a plurality of rod-shaped piezoelectric bodies 2a into a plurality of elongated independent cylinders formed by the groove of the pressure base 31a and the pressure chamber cover plate 32a, the assembly is simplified and the injection characteristics are made uniform. In terms of etc., it cannot be said to be sufficient.

FIG. 2 is a schematic exploded perspective view of a multi-nozzle head showing a structure in which these points are solved in an easy-to-understand manner.
In this multi-nozzle head, a comb-shaped piezoelectric body 2b including a plurality of elongated branches is fitted on a pressure chamber base 31b having a plurality of elongated grooves via a lower spacer 11a.
A pair of electrodes 8b is provided on the front and back of each branch of the comb-shaped piezoelectric body 2b. The front end of the groove of the pressure chamber base 31b is closed by a nozzle member 6b having a plurality of nozzles 5a.

As a result, a plurality of pressure chambers are formed between the nozzle members 6b and the tips of the branches of the comb-shaped piezoelectric body 2b. The pressure chamber cover plate 32b includes a plurality of ink supply holes 7b for supplying ink to the plurality of pressure chambers. An ink tube fixing plate 33b is further fixed on the pressure chamber cover plate 32b. The ink tube fixing plate 33b includes a plurality of ink tube fixing holes corresponding to the plurality of ink supply holes 7b.

In the multi-nozzle head configured as described above,
It will be appreciated that by applying a recording signal voltage to a selected set of the plurality of sets of electrodes 8b, ink drops can be ejected from the corresponding nozzles 5b. In the multi-nozzle head of FIG. 2, since the comb-shaped piezoelectric body 2b having a plurality of elongated branches is fitted into the pressure chamber base 31b of a body having a plurality of elongated grooves, individual inkjet heads can be used. It will be appreciated that assembly is much easier compared to conventional multi-nozzle heads that assemble into a multi-nozzle head. Further, the multi-nozzle head of FIG. 2 can make the ejection characteristics among the nozzles uniform as compared with the conventional multi-nozzle head in which individual ink jets are assembled.

FIG. 3 is a perspective view schematically showing a piezoelectric body used in a multi-nozzle head according to another embodiment of the present invention. The comb-shaped piezoelectric body 2c in FIG. 3 is the comb-shaped piezoelectric body in FIG.
Although similar to 2b, an integrated circuit 12 is provided on the comb-shaped piezoelectric body 2c in FIG. The integrated circuit 12 includes a driver circuit for generating a recording signal voltage applied to the electrodes 8c provided on each of the elongated branches of the piezoelectric body. By doing so, the number of wires up to the piezoelectric body in the multi-nozzle head can be significantly reduced.

EFFECTS OF THE INVENTION According to the present invention, the piezoelectric body is integrally formed in a comb shape including a plurality of elongated branches, and the guide member mechanically includes the main length of each of the plurality of branches of the piezoelectric body. It includes a plurality of elongated tubes for protection. Therefore, since each branch of the piezoelectric body can be thinned, not only can a miniaturized multi-nozzle head be provided, but also a multi-nozzle head that can be easily assembled can be provided.

[Brief description of drawings]

FIG. 1A is a schematic cross-sectional view of an inkjet head provided to facilitate understanding of the present invention. FIG. 1B is a partially enlarged view of FIG. 1A. FIG. 1C is a partial cross-sectional view taken along the line 1C-1C when the inkjet head of FIG. 1A is a multi-nozzle head. FIG. 2 is a schematic exploded perspective view showing a multi-nozzle head according to an embodiment of the present invention. FIG. 3 is a schematic perspective view showing a comb-shaped piezoelectric body in a multi-nozzle head according to another embodiment of the present invention. FIG. 4 is a sectional view schematically showing a conventional inkjet head. In the figure, 2a, 2b, 2c are piezoelectric bodies, 31a, 31b are pressure chamber bases, 32a, 32b are pressure chamber cover plates, 33a, 33b are ink tube fixing plates, 4a are pressure chambers, 5a, 5b are nozzles, 6
Reference numerals a and 6b are nozzle members, 7a and 7b are ink supply holes, 8a, 8b and 8c are electrodes, 9 is a seal film, 10 is an ink tube, 11a and 11b are spacers, and 12 is an integrated circuit. Note that, in FIGS. 1A to 1C, the same reference numerals indicate the same contents or corresponding portions.

Claims (1)

[Claims] 1. A guide member including a plurality of elongated cylinders, a comb-shaped piezoelectric body including a plurality of elongated branches inserted from one end of the plurality of cylinders, and the other end of the plurality of cylinders. A plurality of pressure chambers formed between the ends of the plurality of branches, a plurality of ink supply holes for supplying ink to the plurality of pressure chambers, and for ejecting ink droplets from the plurality of pressure chambers A plurality of nozzles and a plurality of sets of electrodes, one set for each branch of the piezoelectric body, each of the plurality of cylinders including the main length of each of the plurality of branches of the piezoelectric body. Each of the branches is mechanically protected, and when a recording signal voltage is applied to a selected set of the plurality of sets of electrodes, the tip of the corresponding branch of the piezoelectric body is displaced, Ink drops are ejected from the corresponding nozzles according to Inkjet head.