JPH08244219A - Ink jet recording head - Google Patents

Abstract

PURPOSE: To discharge the remaining air at the time of supplying ink in a short injection time, and to normally inject the ink by continuously recessing at the center of the bottom from the periphery of a pressurizing chamber, and forming a nozzle or a channel to the nozzle at the center of the recess. CONSTITUTION: An ink jet recording head injects the ink of the pressurizing chamber 2 of a board 1 from a nozzle 3 by the deformation of a piezoelectric element connected to diaphragm. The chamber 2 is continuously recessed at the center of the bottom, and the nozzle 3 or a channel to the nozzle 3 is formed at the center. The nozzle 3 is penetrated by irradiation with an excimer laser after a blind hole is formed by injection molding or cutting. Thus, the chamber 2 is so formed that the surface to the nozzle 3 become oblique surfaces 2a, 2b to eliminate a step, thereby eliminating a stagnation due to the step, and bubbles can easily be discharged out of the head from the nozzle 3 by the viscosity of the ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a recording head used in a recording apparatus to keep ink ejection of the recording head normal.

[0002]

2. Description of the Related Art The ink jet recording head according to the present invention is widely used in printers, facsimiles and the like at present because of its simple structure and few failures. 3A and 3B are explanatory views of a recording head having five nozzles, FIG. 3A is a plan view of a part of the cross section, and FIG. 3B is a cross sectional view along an ink flow path. Ink reservoir 12, plural diaphragms 13, pressurizing chamber 1
4, synthetic resin substrate 11 provided with nozzle 15
Are bonded to the vibration plate 16 that is bonded to the piezoelectric element 18 via the conductive film 17. Ink is filled from an ink supply hole (not shown) to the pressure chamber 14 via the ink reservoir 12 so that no bubbles remain, and a voltage is applied by means (not shown) to deform the piezoelectric element 18 into the pressure chamber 14 and squeeze it. The fluid resistance of 13 was used to eject ink from the nozzles 15 as ink points to perform printing / drawing.

The diameter of this nozzle is several tens of μm, and injection molding cannot be performed with the current technology.
As shown in No. 4, processing with a high-power excimer laser, cutting and then processing with the same laser, or adhering a metal plate that is an electroplating layer with nozzles formed by electroforming Was there.

[0004]

In the example described in the prior art, the nozzle 1 is provided from the bottom end of the pressurizing chamber 14 through the vertical hole.
5 is formed, a step 19 is apt to occur on the outer end portion of the nozzle 15 due to the structure. When ink is supplied, air remains in the space due to the step 19, and the ink pressure due to the deformation of the piezoelectric element is equal to or more than a predetermined value due to the compression of air. In some cases, the ink could not be ejected normally because the pressure could not be increased, and the bubbles were not eliminated by some vibration.

For example, in a 20-minute injection experiment in which a pulse voltage of 4 kHz is applied to the piezoelectric element 18, the number of samples is 100.
Two nozzles out of the nozzles caused ejection failure, and when observed with a stereoscopic microscope, bubbles with a diameter of about 20 μm were present in the upper corners of the nozzle holes. An object of the present invention is to provide a recording head capable of ejecting this air in a short ejection time and ejecting ink normally.

[0006]

According to the present invention, in a recording head in which ink in a pressure chamber of a substrate is ejected from a nozzle by deformation of a piezoelectric element bonded to a vibrating plate, the center of the pressure chamber is continuous from the periphery. Then, a nozzle or a flow path leading to the nozzle is formed in the center.

[0007]

According to the present invention, the pressure chamber is formed so that the surface up to the nozzle is inclined to eliminate the step.
The stagnation due to the step is eliminated, and the bubbles easily discharge from the nozzle to the outside of the recording head due to the viscosity of the ink.

[0008]

1 is a sectional view of an ink jet recording head according to the present invention, in which (a) is a main part view of an ink flow path, and (b) is a main part of a plurality of pressurizing chambers. The figure is shown. A nozzle 3 and slopes 2a and 2b are provided at the center of an ink reservoir 12 and a pressurizing chamber 2 on a synthetic resin substrate 1. The nozzle 3 is formed with a blind hole by injection molding or cutting, and then penetrated by irradiation with an excimer laser.
The plane size of the pressurizing chamber 2 in the actual machine was 2.5 mm × 3 mm, and in the injection experiment in which the pulse voltage of 4 kHz was applied for 20 minutes, the injection failure was 0 at 100 nozzles of the present invention.

Further, the jetting speed was 11 m / s as the average value of 40 nozzles of the present invention, which was better than the average value of 8 nozzles of 200 nozzles of the conventional product. FIG. 2 is a cross-sectional view of the main part in another embodiment of the present invention, in which a sloped surface 2b and a flow path 2c are provided on a substrate 6 by injection molding, and a nozzle plate 7 in which a nozzle 7a is processed is provided in the flow path. It is a structure that is attached to the end face.

[0010]

According to the present invention, since a step at the outer end of the nozzle is eliminated and the nozzle is sloped, it is possible to realize a recording head having a high ejection force with no bubbles remaining, which is small and has high printing quality. A recording head and a recording device can be provided.

[Brief description of drawings]

1A and 1B are cross-sectional views of an embodiment of the present invention, in which FIG. 1A is a main part view of an ink flow path, and FIG.

FIG. 2 is a sectional view of a main part in another embodiment of the present invention.

3A and 3B are explanatory views of a conventional example, FIG. 3A is a plan view of a partial cross section, and FIG. 3B is a cross sectional view taken along an ink flow path.

[Explanation of symbols]

 1 Substrate 2 Pressurizing Chamber 2a Slope 3 Nozzle 6 Substrate 7 Nozzle Plate 7a Nozzle 14 Pressurizing Chamber 15 Nozzle

Claims (1)

[Claims] 1. In a recording head in which ink in a pressure chamber of a substrate is ejected from a nozzle by deformation of a piezoelectric element bonded to a vibration plate, the center of the bottom surface of the pressure chamber is continuously recessed from the periphery,
An ink jet recording head characterized in that a nozzle or a flow path leading to the nozzle is formed in the center thereof.