JPH04329145A - Multinozzle ink jet head - Google Patents

Abstract

PURPOSE:To suppress the effect of an adjacent pressure chamber in a multinozzle ink jet head used in a non-impact type ink jet printer performing recording by injecting ink particles to a recording medium. CONSTITUTION:A multinozzle ink jet head 11 is equipped with a plurality of pressure chambers communicating with nozzles at one ends thereof and filled with ink from the other ends thereof and a plurality of the pressure generating means 15 arranged on the vibration plates 16 being in contact with the respective pressure chambers 17 in opposed relation to the respective pressure chambers 17. Notches 19 are provided to the parts between at least the pressure generating means 15 of the respective vibration plates 16 and achieve function suppressing the effect on the vibration plates 16 on the adjacent pressure chamber 17 at the time of recording.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-nozzle inkjet head used in a non-impact type inkjet printer that performs recording by ejecting ink particles onto a recording medium.

[0002] In the non-impact recording method, various methods for recording information patterns are used, and these are known as various recording devices such as electrostatic type, discharge type, and thermal type. However, all of these require specially treated recording media. On the other hand, inkjet recording devices using the same non-impact recording method record by depositing ink droplets on recording paper in a predetermined information pattern, and have advantages such as high speed printing, low noise, and low running costs due to the use of plain paper. Although it has been attracting attention in recent years due to its unique characteristics, it is desired to improve the image quality so that even higher image quality can be obtained.

0003

2. Description of the Related Art An inkjet head has a plurality of ink passages, one end of which communicates with each nozzle, and a piezoelectric element fixed on a diaphragm in contact with the ink passages, facing a pressure chamber that is part of the ink passages. The ink passage is filled with ink supplied from an ink supply source. During recording, voltage is applied to the piezoelectric element in a predetermined pattern. As a result, pressure is generated in the pressure chamber, and ink particles are ejected from the nozzle to perform recording.

[0004] In this multi-nozzle inkjet head, conventional piezoelectric elements are attached one by one on a diaphragm to face each pressure chamber by adhesive. FIG. 3 is an explanatory view of the configuration and operation of the pressure generating section, FIG. 3(A) is a sectional view showing the configuration, and FIG. 3(B) is a sectional view showing the operation. In FIG. 3A, 1 is a pressure chamber that is a part of an ink passage formed between a substrate 2 and a diaphragm 3, and 4 is a piezoelectric element.

[0005]

However, in the conventional structure described above, the positional accuracy of the piezoelectric element is low, which causes variations in characteristics between nozzles. Furthermore, bonding the piezoelectric elements takes time, which becomes a serious problem as the number of nozzles increases. Therefore, in order to facilitate head manufacturability and reduce variations in characteristics, it has already been proposed to cover a plurality of pressure chambers with one piezoelectric element and cut the piezoelectric element in correspondence with each pressure chamber. The configuration of the pressure generating section obtained by this method is similar to that shown in FIG. 3(A).

[0006] Recently, as the density of inkjet heads has increased, the distance between adjacent piezoelectric elements (pressure chambers) has become narrower, and as a result, the influence of adjacent piezoelectric elements has a large influence on the characteristics. That is, when adjacent piezoelectric elements are driven simultaneously, the flying speed of the ink particles decreases compared to when they are not driven, the amount of ejected ink decreases, and the diameter of the recording head becomes smaller.

The cause of this is mainly due to the effect through the diaphragm, and when the adjacent piezoelectric element 4 is driven as shown in FIG. The plate becomes difficult to bend, and as a result, the speed at which ink particles fly (particle speed) decreases, and the amount of ejected ink also decreases accordingly. The decrease in particle velocity causes a lateral positional shift of the recording dots, and the decrease in the amount of ejected ink also causes the diameter of the recording dots to decrease.

An object of the present invention is to provide a multi-nozzle inkjet head that can suppress the influence of adjacent pressure chambers.

[0009]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention includes a plurality of pressure chambers each having one end communicating with a nozzle and filled with ink supplied from the other end. In a multi-nozzle inkjet head comprising a plurality of pressure generating means disposed facing each pressure chamber on a diaphragm in contact with the diaphragm, a notch is provided in at least a portion of the diaphragm between each of the pressure generating means. The configuration (first configuration) is characterized by including the following.

[0010] Furthermore, in the multi-nozzle inkjet head of the first configuration, the width of the pressure generating means is wider than the width of the pressure chamber directly below the pressure generating means (second configuration). shall be.

[0011]

[Operation] During recording, the pressure generating means on a predetermined pressure chamber is activated. As a result, pressure is generated in the pressure chamber and ink is ejected from the nozzle. The ejected ink is ejected and adheres to the recording paper, and recording is performed. During this recording, since the diaphragm is cut at least between each pressure generating means, the influence on the diaphragm in the adjacent pressure chamber is suppressed.

As a result, even if the pressure generating means in the adjacent pressure chambers are simultaneously driven, there is almost no effect on the flight of ejected ink particles (particle velocity, amount of ejected ink), and the positional accuracy of recording dots and recording A good dot diameter can be maintained. Note that the cut into the diaphragm is made by cutting each pressure generating means into one
In the case of cutting from a sheet, the cutting can be done at the same time, reducing the working time.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 2 is a partially cutaway perspective view showing a multi-nozzle inkjet head 11 to which this embodiment is applied. The inkjet head 11 is made of SUS or the like, and one end communicates with each nozzle 12 and the other end communicates with ink. It includes a plurality of ink passages 14 communicating with the storage portion 13 and a plurality of piezoelectric elements (pressure generating means) 15.

Each piezoelectric element 15 is fixed by adhesive on a vibration plate 16 in contact with the ink passage 14 so as to face a pressure chamber 17 that is a part of each ink passage 14. Each piezoelectric element 15 is formed by cutting a single piece, as described above. In the piezoelectric element 15, electrodes are uniformly formed on the side in contact with the vibration 16, and electrodes are formed only on the other side facing the pressure chamber 17. The ink passage 14 is filled with ink 18 that is supplied through the ink storage section 13 from an ink supply source such as an ink cartridge (not shown).

The diaphragm 16 also has a structure shown in FIG.
As shown in detail in A), cuts 19 are made between each piezoelectric element 15. Note that this cut may be made so as to surround the piezoelectric element 15. 20 is a head substrate.

The structure of the present invention is as described above, and its operation will be explained next.

[0018] In the conventional structure in which no cuts are made in the diaphragm, when adjacent piezoelectric elements are driven simultaneously, the particle velocity decreases by about 10% and the amount of ejected ink decreases by about 9% compared to when they are driven individually. did. On the other hand, when the notches 19 were made as in this example, when the adjacent piezoelectric elements 15 were driven simultaneously, no change was observed in both the particle velocity and the amount of ejected ink compared to when they were driven individually. this is,
By making the cut 19, the adjacent pressure chamber 1
This is because the influence on the diaphragm above 7 is suppressed as shown in FIG. 1(B). As a result, it was possible to maintain good position accuracy and dot diameter of the recorded dots.

Note that the deeper the cut into the diaphragm, the smaller the influence on the diaphragm on the adjacent pressure chamber. The depth of cut is determined based on manufacturing conditions and property conditions. Figure 1
This example shows an example in which a cut is made by the thickness of the diaphragm. Further, as shown in FIG. 1, it is more effective if the width of the piezoelectric element 15 is made wider than the width of the pressure chamber 17 directly below the piezoelectric element 15.

The inkjet head can also be made of glass, but in this case, a conductive layer is formed on the diaphragm using conductive paint. When cutting a single piece to form a piezoelectric element, this conductive layer is isolated from the surroundings by making cuts on all sides up to the diaphragm, and it is not possible to establish conduction with the side of the piezoelectric element that is in contact with the diaphragm. It's difficult. Therefore, by not making cuts in the diaphragm on two of the four sides (in practice, making cuts only between each piezoelectric element), the signal terminal can be passed through the conductive layer formed on the diaphragm. It becomes possible to form.

[0021]

As described above, according to the present invention, it is possible to suppress the influence on the diaphragm on the adjacent pressure chamber during recording, which eliminates the conventional problem when driving adjacent piezoelectric elements simultaneously. This makes it possible to prevent the drop in particle velocity and the amount of ejected ink, which would otherwise have occurred, and to maintain good positional accuracy and dot diameter of the recorded dots. Note that it is more effective if the width of the pressure generating means is made wider than the width of the pressure chamber directly below the pressure generating means. Furthermore, since the load on the piezoelectric element is reduced, the effect of reducing the drive voltage can also be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the structure and operation of a pressure generating section of a multi-nozzle inkjet head according to an embodiment of the present invention; FIG.
is a sectional view showing the structure, and FIG. 1(B) is a sectional view showing the action.

FIG. 2 is a partially cutaway perspective view showing a multi-nozzle inkjet head to which the present invention is applied.

FIG. 3 is an explanatory view of the structure and operation of a pressure generating section of a conventional multi-nozzle inkjet head; FIG. 3(A) is a sectional view showing the structure, and FIG. 3(B) is a sectional view showing the operation.

[Explanation of symbols]

11 Multi-nozzle inkjet head 12
Nozzle 14 Ink passage 15 Piezoelectric element (pressure generating means) 16 Vibration plate 17 Pressure chamber 18 Ink 19 Notch

Claims (2)

[Claims] 1. A plurality of pressure chambers (17), each of which has one end communicating with a nozzle and which is filled with ink supplied from the other end.
In a multi-nozzle inkjet head comprising a plurality of pressure generating means (15) disposed on a vibration plate (16) in contact with each pressure chamber (17) and facing each pressure chamber (17), the vibration A notch (1
9) A multi-nozzle inkjet head. 2. The multi-nozzle inkjet head according to claim 1, wherein the width of the pressure generating means (15) is wider than the width of the pressure chamber (17) directly below the pressure generating means (15).