JPS62151347A - Ink jet nozzle in ink jet recorder - Google Patents

Abstract

PURPOSE:To obtain an ink jet nozzle adaptable to a recording of increased speed and enhanced quality, by a method wherein an orifice for discharging ink drips is provided and a specific orifice length to an ink intake portion is determined. CONSTITUTION:To conduct a high-speed recording, a recording frequency of fr=3kHz or more and an ink discharge rate within V=5-10m/sec are required. An orifice length L in the range of 0.5-5 times the diameter (d) can meet these requirement. In the other range than the above, i.e. in the range below L/d=0.5, a so-called splash phenomenon occurs in which an ink is splashed without becoming ink drips suitable for recording. In the range above L/d=5, reduction of a recording frequency fr as well as a discharge rate V generates intermittent discharge, whereby a stable discharge cannot be obtained. Therefore, an ink jet nozzle of the above size can adapt to an increased recording speed and realize a high recording quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ink jet nozzle used in an ink jet recording device.

[Prior Art] In recent years, inkjet recording devices have come into widespread use as recording devices in computer systems and the like.

An inkjet recording device records fine dots by jetting liquid ink from a fine refill having a diameter of about several tens of lumens, and therefore the shape of the ink jet nozzle greatly influences performance and recording characteristics. In particular, in inkjet recording devices that perform multicolor recording using multiple nozzles, if all nozzles are not formed with the same shape and dimensions, it will not be possible to perform equivalent recording for each color, and the recording quality will deteriorate. Significant decline.

Furthermore, in a region where the recording frequency is high, the allowable drive voltage range (voltage 70-once) of the ejection energy generating element for ejecting ink sharply narrows. For this reason, depending on the shape and dimensions of the nozzle, it becomes impossible to eject droplets in response to electrical signals input in the high frequency range of the recording frequency, increasing the probability of non-ejection. This phenomenon occurs at several KHz
This has already occurred since then, and is one of the factors that prevents faster recording speeds.

[Problems to be Solved by the Invention] As described above, since the inkjet recording device ejects ink using relatively small pressure fluctuations within its ejection tube,
The discharge conditions are very delicate, and the nozzle shape and dimensions must be strictly controlled. However, in the past, the glass tube as a hollow base material was simply heated and stretched, and the position of the orifice diameter (nozzle tip diameter) was found using a microscope.
A manufacturing method called C-cutting has been used. For this reason,
Such manufacturing methods do not take into account dimensions and quality related to the length from the tip of the orifice to the introduction section for introducing ink into the orifice, which are important factors for increasing the recording speed.

[Means for Solving the Problems] The present invention has been made in view of the above problems, and it is an object of the present invention to provide an ink jet nozzle that can be adapted to higher recording speeds and higher recording quality. .

In order to achieve this object, the present invention includes an orifice for ejecting ink droplets and an ink introduction section continuous with the orifice, and the orifice length from the orifice to the ink introduction section is as long as the length of the orifice. The diameter of the orifice is 0.5 to 5 times the inner diameter of the tip of the orifice, and the orifice has a circular tube shape with an inclination of 5 degrees or less relative to the axis from the orifice to the ink introduction section.

[Function] According to the present invention, it is possible to realize an ink ejecting nozzle that can increase the recording speed and improve the recording quality.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

The present invention particularly focuses on the following points.

From the tip of the orifice toward the ink introduction section,
It is preferable that the tube be formed into a straight tube shape or a tapered circular tube shape with an inclination of 5 degrees or less with respect to the axis. The relationship between the length of the straight pipe section (or the length of the tapered section, hereinafter simply referred to as orifice length) and the diameter of the tip is an important factor in evaluating the performance of the orifice.

Figure 1 shows the ratio L between orifice length and orifice diameter d.
/d, ejection speed V, and recording frequency f'', which were obtained through experiments by one applicant.For high-speed recording, the recording frequency should be fr=3KHz or more, and the ejection speed should be V=
It is required to be in the range of 5 to 10 m/sec. Therefore, as is clear from FIG. 1, the orifice length L that satisfies these conditions is in the range from 0.5 times to 5 times the diameter d. In areas outside this area where L/d = less than 0.5, a so-called splash phenomenon occurs in which ink scatters without forming droplets suitable for recording, and in areas where L/d exceeds 5, the recording frequency fr Since both the discharge speed and the discharge speed V decrease, intermittent discharge occurs, and stable discharge cannot be obtained.

Therefore, a method for manufacturing a nozzle in the range of 0.5≦L/d≦5 with high precision will be described.

In this example, a fine wire such as a piano wire is inserted into a glass tube as a hollow base material, and then the glass tube is heated and stretched to form a nozzle and cut. Thereafter, the fine wires inside the tube are dissolved and removed using a chemical such as nitric acid to form a nozzle. A nozzle formed in this way has a smoother in-plane surface than a nozzle formed by drawing out the fine wire, and can achieve stable ejection.

2 to 5 show the sequential manufacturing process of the Gould type ink ejection nozzle according to this example.

First, FIG. 2 shows a state in which a fine metal wire 2 having a diameter slightly smaller than the desired orifice diameter d is inserted into a glass tube 1. Here, the length of the fine wire 2 is smaller than the length of the glass tube l. Keep it large.

FIG. 3 shows a state in which a glass tube 1 through which a fine wire 2 is passed is heated locally and uniformly by a heater 3.

FIG. 4 shows a state in which the heated glass tube 1 is stretched from side to side. At this time, heating by the heater 3 shall be canceled. At this time, the heated portion 1' of the glass tube 1
is stretched along the fine wire 2, and since the thermal conductivity of that part and the fine wire 2 inside is greatly different, a slight gap is created between the stretched glass tube 1 and the metal fine wire 2, and The glass tube 1 is solidified without glass being welded to the fine wires 2. Therefore, by pulling out the fine wire 2 from the glass tube 1, two nozzles are obtained from one glass tube. Formed into a mechanically smooth shape.

FIG. 5 shows the portion of the nozzle 5 that will become the orifice projected onto the projector 4. Therefore, the orifice length is 0.
What is necessary is to cut it according to the projection view so that it has a desired dimension that satisfies 5≦L/d≦5.

For this cutting, for example, a cutting device 6 is equipped with a diamond blade attached to a spindle that rotates stably at high speed.
can be used. By immersing the thus formed nozzle in a chemical and applying ultrasonic vibration, for example, to dissolve and remove fine lines within the tube, a nozzle with an extremely smooth inner surface can be formed.

[Effects] As described above, according to the present invention, it is possible to realize an ink ejecting nozzle that can cope with an increase in printing speed and has high printing quality.

[Brief explanation of drawings]

FIG. 1 is a characteristic curve diagram showing the relationship between the ratio of orifice length and diameter, ink ejection speed, and recording frequency. Fig. 2 is an explanatory diagram showing a state in which a fine wire is inserted into a glass tube, Fig. 3 is an explanatory diagram showing a state in which a glass tube through which a fine wire is passed is heated, and Fig. 4 is an explanatory diagram showing a state in which it is stretched after heating. FIG. 5 is an explanatory diagram showing a state in which a stretched nozzle is cut. 1...Glass tube, 2...Fine wire. 3... Heater, 4... Projector, 5... Nozzle, 6... Cutting device. Figure 1

Claims (1)

[Scope of Claims] 1) An orifice for ejecting ink droplets and an ink introduction section continuous with the orifice, and the length of the orifice from the orifice to the ink introduction section is determined by the length of the orifice at the tip of the orifice. An inkjet recording device characterized in that the orifice has a circular tube shape with an axis line having an inclination of 5 degrees or less from the orifice line end toward the introduction part. Ink jet nozzle. 2) In the ink jet nozzle of the ink jet recording apparatus according to claim 1, the orifice is in the shape of a straight tube or in the shape of a tapered circular tube with an inclination of the axis of 5 degrees or less. Ink jet nozzle of the device.