JPS6233076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink-on-demand type ink jet head, and more particularly to a multi-nozzle head having a large number of pressurizing chambers.

Ink-on-demand type inkjet has a simple structure and is expected to be used as a low-cost printing device. However, since the response is low, a large number of nozzles are integrated into a multi-nozzle head. When the number of nozzles increases, the density of the corresponding pressurizing chambers increases, resulting in a problem that the stability of ink ejection decreases. According to the research of the present inventors,
The cause of this is that vibrations from adjacent pressure chambers are transmitted and ink flows out from nozzles to which a drive signal is not applied, changing the wet state of the nozzle surface, or between pressure chambers to which a drive signal is applied. It was found that this is because the state of ink ejection changes due to mutual interference.

Therefore, it is an object of the present invention to provide a multi-nozzle head that is free from the adverse effects of vibration and can eject ink stably.

The gist of the present invention is to make a diaphragm from a material with a low modulus of elasticity such as plastic, laminate a member with a high modulus of elasticity such as a metal plate on the part corresponding to the pressurizing chamber, and connect a piezoelectric element thereto. This is intended to suppress the influence of vibration between adjacent pressurized chambers.

Embodiments of the present invention will be described below with reference to FIG. Reference numeral 1 denotes a substrate made by injection molding of ABS, on the surface of which flow paths including a pressurizing chamber 2, a nozzle 3, a supply preparation chamber 4, etc. are formed. Reference numeral 5 denotes a diaphragm made by injection molding of ABS, which has a thickness of 0.4 mm, and has a recessed part 0.2 mm deep as a positioning part 51. The diaphragm 5 and the substrate 1 are bonded together using dope cement made by dissolving ABS resin with a solvent. Reference numeral 6 is a highly elastic member made by punching a 0.1 mm stainless steel plate with a press, and is divided into vibrating parts 62 of a type approximately corresponding to each pressurizing chamber by a vibration isolation slit 61.
It is composed of an evaporation prevention part 63 corresponding to the evaporation prevention part 63, a connecting part 64 which connects each of these parts to form a single component, and the like. 7 is a piezoelectric element based on lead zirconate titanate, and electrodes are formed on the upper and lower surfaces. Although only one piezoelectric element 7 is shown in FIG. 1,
It goes without saying that seven units are required for each pressurizing chamber 2. The piezoelectric element 7, high elastic member 6, and diaphragm 5 are each bonded with epoxy resin. 8 is a wiring connected to the upper surface electrode of each piezoelectric element 7, and 9 is a common wiring connected to the high elastic member 6. In this embodiment, the channel is formed on the substrate 1, but it may be formed on the lower surface of the diaphragm 5, or the channel wall may be made of another member.

In the above configuration, a signal from a control circuit (not shown) is applied via the wiring 8 and the common wiring 9, and the piezoelectric element 7, the vibrating part 62 of the high elastic member 6,
The diaphragm 5 cooperates to change the volume of the pressurizing chamber 2,
Ink is ejected from the nozzle 3.

At this time, the vibration between adjacent pressurized chambers is 0.2 mm thick.
This is only transmitted through the positioning portion 51 of the ABS, and since the modulus of elasticity of ABS is as low as 2.1×10 ⁹ N/m ² , it is hardly a problem. That is, the elastic modulus of the piezoelectric element 7 is 5.9×10 ¹⁰ N/m ² , and the elastic modulus of stainless steel used as the highly elastic member 6 is 2×10 ¹¹ N/m ² , which is one or two orders of magnitude higher than that of ABS. Since the girder also has a high elastic modulus, vibration in each pressurizing chamber is suppressed by vibration prevention slits 6.
It is thought that the vibrations are independent and almost completely separated by

As can be seen from the above description, according to the present invention,
By changing the volume of the pressurizing chamber using a diaphragm made of a low elastic modulus material, a high elastic member placed corresponding to the pressurizing chamber, and a piezoelectric element bonded to the high elastic member, the adjacent It is possible to provide a multi-nozzle head with stable ink ejection that is less affected by vibration between pressure chambers.

Furthermore, by using plastic as the low modulus material as in the embodiment, an inexpensive head with low molding and assembly costs can be obtained.

Furthermore, if a conductive material such as a metal plate is used as the highly elastic member, conduction to the bottom electrode of each piezoelectric element can be easily established, and there is no need to separately consider connection to the bottom electrode.

In addition, since high-elasticity materials generally have low gas permeability, the flow paths other than the pressurized chamber are also covered at the same time, as in the evaporation prevention section 63 in Figure 1, to prevent ink evaporation and air intrusion from the outside. can.

Furthermore, by combining the highly elastic member and the piezoelectric element, the deformation of the piezoelectric element can be effectively converted into a change in the volume of the pressurizing chamber, which has the effect of reducing the driving voltage. For example, FIG. 2 shows the driving voltage (solid line) for a head using the highly elastic member of the present invention and the driving voltage (dotted line) for a head using a plastic diaphragm that does not use the highly elastic member. The horizontal axis indicates the thickness of the diaphragm and the high elastic member. It can be seen that when the optimum thickness is selected, the drive voltage of the head using the highly elastic member of the present invention is low. Note that the driving voltage of the present invention is lower than that of a head whose entire surface is covered with a metal plate as a diaphragm. This is thought to be due to the fact that the vibration system is deformed almost by being supported around the periphery, so the deformation efficiency is better for the same force than in the case where the periphery is fixed. In addition, the vibration plate of the head is made of a low-elasticity material, and the high-elasticity member laminated to the vibration plate is provided with a vibration isolation section, so that the vibration of the piezoelectric element is not transmitted to the adjacent pressurizing chamber. This makes it possible to increase the density of the head and facilitate manufacturing. In addition, as mentioned above, if the diaphragm is made of a material with a low elastic modulus, even if the piezoelectric element vibrates, it will have low elasticity, so the vibration will not be transmitted to the adjacent pressurizing chamber, and the pressurizing chamber Only the part of the diaphragm where the high-elastic member is arranged vibrates well, and since the vibration isolating part is provided in the part where the high-elastic member corresponds to the space between the pressurizing chambers, the deformation is performed to support the periphery instead of fixing it around the periphery. The diaphragm can be sufficiently deflected in a small area or even to the corner, making it possible to increase the density of heads such as pressurized chambers.

As described above, according to the present invention, it is possible to obtain a head that is less affected by vibrations between adjacent pressurizing chambers. Furthermore, it has the following effects: lower manufacturing costs, easier electrical connection, prevention of ink evaporation, lower drive voltage, etc., and can be widely applied to printers, plotters, facsimile machines, copiers, etc.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure shows the driving voltages of the head of the present invention and a conventional head. 1...Substrate, 2...Pressure chamber, 3...Nozzle, 5
... Vibration plate, 6 ... Highly elastic member, 7 ... Piezoelectric element.

Claims (1)

[Claims] 1. A diaphragm made of a low elastic modulus material, a substrate laminated with the diaphragm and forming a plurality of pressure chambers adjacent to each other in a plane between the diaphragm, and arranged on the diaphragm. An inkjet head comprising: a highly elastic member provided with a vibration isolating portion in a portion corresponding to the pressurizing chamber; and a piezoelectric element disposed on the highly elastic member at a position corresponding to the pressurizing chamber.