JPS63122559A - Surface treating method for ink jet recording head - Google Patents

Abstract

PURPOSE:To enable reliable surface treatment, by allowing substance to fly from a direction inclined against a normal of a delivery port, and adhering it to the end face thereby preventing it from adhering to the interior of the delivery port. CONSTITUTION:A surface layer 12 is formed through vapor deposition, and the flying direction N2 of substance (evaporated gas) being adhered thereto inclined against a normal N1 of a delivery port 6. The angle theta is not required to be defined strictly and may be in the range of 45 deg.<theta<90 deg.. Since the vapor deposition is carried out in a limited range of the end face of delivery port and the interior of delivery port, a thin film is formed substantially only on the surface through the vapor deposition. The surface layer 12 may be formed through sputtering under a low vacuum as well as vapor deposition. When vapor deposition is made, a head is rotated stepwise around a shaft N1, or rotated continuously so as to form the thin film uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an inkjet recording head.

[Prior Art] With the spread of computers in recent years, various application models have been actively developed. In particular, the development and spread of office equipment for office automation, such as copying machines, facsimile machines, word processors, and so-called personal computers, has been remarkable.

In these office machines, a so-called printer is an essential device for outputting processed data or text.

Conventionally, such printers include impact printers such as wire dot printers and laser beam printers that use electrostatic copying.

Non-impact printers such as thermal transfer printers are used, but printers using inkjet recording methods have recently attracted attention for their excellent features, and various types of printers are being developed.

It goes without saying that it is desirable for prints and images produced by a printer to be beautiful and precise, and this is also the goal of these printer technologies.

The first inkjet recording head for this purpose is
There is one in which the ink ejection nozzle is formed small and the ink is ejected at high speed and with high density. In addition, in other inkjet recording heads, it is possible to arrange ink ejection nozzles small and close together, and for this purpose, a large number of ejection ports are arranged closely together using a microfabrication method using so-called microlithography technology. There are known methods for producing it.

FIGS. 2 and 3 show an example of the structure of a conventional inkjet recording head manufactured by such a method. In the figure, 1 is a first substrate made of, for example, a silicon wafer, and 2 is a first substrate 1 made of, for example, 5in2.
It is a layer formed on the surface. 3 is a nozzle wall formed by a method such as lithography, 4 is a second substrate formed of a glass plate, 5 is an adhesive layer on the upper part of the nozzle wall 3, and 6 is an ink discharge port of the nozzle. It is. In such a recording head, the nozzle wall 3 has, for example, a height of 25 μm and a width of 20 μm, and the ejection opening 6 is extremely precisely machined to have the same dimensions as the nozzle wall 3.

[Problems to be Solved by the Invention] FIGS. 4(A) and 4(B) show side cross sections of the inkjet recording head shown in FIGS. 2 and 3, in which ink 7 is ejected to form ink droplets 8. Two examples of states are shown. Here, FIG. 4(A) shows a state in which ink droplets are ejected straight without the nozzle end surface 9 getting wet with ink, and FIG.
B) is a state in which ink droplets are about to be ejected in a curved direction because a part of the nozzle end face 9 is wetted with ink before ejection.

The ejection port end face 9 is used not only when ink gets wet and spreads during ink ejection, but also when the head is mechanically moved while printing in an apparatus that performs recording by mounting an inkjet recording head on a carriage, or when the carriage Due to mechanical vibrations that occur when the ink reaches the edge of the recording medium and performs a return operation, the ink 7 in the nozzle may overflow from the nozzle tip to the outside, that is, to the end surface 9 of the nozzle tip, wetting it. be.

In this case, when the ink that overflows and wets the end face 9 returns to the ejection port, or when the area around the ejection port is uniformly wetted, the ejection direction of the ejection port ink droplets 8 is as shown in FIG. 4(A). The ejection state, that is, the recording state becomes stable.

However, with conventional inkjet recording heads,
Due to the difference in wettability between the second substrate 4 and the adhesive layer 5, the nozzle end surface 9 may be unevenly wetted, or - After the feet have warmed up, the ink may remain unevenly on the ink end surface 9. Therefore, an unstable discharge state as shown in FIG. 4(II) will occur.

In other words, there is a strong relationship between the wetting of the end face of the ejection port and the surface condition of the end face, and if the surface condition of the end face of the ejection port is not appropriate, an unstable ejection state will occur, and therefore a good recording state cannot be maintained. This also results in a decrease in recording quality.

This is a problem that can occur in the front wheel not only in the inkjet recording head shown in FIGS. 2 and 3, but also in the first inkjet recording head. When the ink ejection ports are provided closely together, wetting occurs around the adjacent ejection ports, so that the wetting areas connect with the adjacent ejection ports, and the effect becomes even greater. As a result, the recorded characters are distorted and the image is disturbed, which has a more serious negative impact on the recording quality and image quality, so the end face of the ejection port needs to be controlled more strictly.

To this end, it is possible to apply a liquid-repellent surface treatment to the end face of the ejection port to repel ink and prevent it from getting wet, but the inside of the ejection port must have a surface that is easily wetted by ink. is desirable. This is because if the leakage inside the ejection port is good, the ink replenishment speed inside the ejection port after ejecting a droplet by one pulse of the drive signal will be correspondingly higher, and therefore it will be possible to repeat ejection at a higher speed. .

Up until now, attempts have been made to adjust the surface shape by coating the end faces of ink ejection ports, that is, to provide a coating layer on the end faces to make the surface uniform and to stabilize the ejection of recording droplets. There is. However, it is technically difficult to carry out coating or surface treatment after forming the ejection port without touching the inside of the ejection port, and if the coating material enters the inside of the ejection port, the recording liquid may be exposed to the ejection port. This could result in unstable discharge conditions. In addition, due to concerns about such negative effects, there are restrictions on the materials that can be used for coating or surface treatment.
This may also result in a reduction in the durability of the surface treatment effect.

The present invention has been made to solve these problems, and aims to eliminate complicated and uncertain surface treatments, insufficient sustainability of surface treatment effects, and limitations on the materials that can be surface treated. There is.

[Means for Solving the Problems] To this end, the present invention provides a surface treatment method for an inkjet recording head in which surface treatment is performed by applying a substance to the end face of the inkjet recording head including the ink ejection ports. It is characterized in that the substance is ejected from a direction oblique to the normal line of the discharge port and is deposited on the end face.

[Function] According to the method of the present invention, when performing surface treatment on the end face of the ejection port of an inkjet recording head by vapor deposition or sputtering, the substance for surface treatment does not adhere to the inside of the ejection port, and Since it adheres to the end face, reliable surface treatment is possible without complicated processes.

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

FIGS. 1(^), (B) and (C) are schematic cross-sectional views showing three examples of inkjet recording heads to which the method of the present invention is applied. In these figures, 10 is a nozzle pipe or nozzle q, 12 is a surface layer treated on the surface of the nozzle pipe or nozzle wall 10 by the following process, and 16 is a liquid flow path communicating with the discharge port 6. Note that FIG. 2B corresponds to the recording head shown in FIGS. 2 and 3 described above.

In this embodiment, the surface layer 12 is formed by a vapor deposition method, and the flight direction N2 of the deposited substance (evaporated gas) is tilted with respect to the direction Hr'i + of the discharge port 6. do. The angle θ formed by N and N2 does not need to be strictly limited, but is generally in the range of 45@<θ<90°. When the flow of evaporated gas has directionality and the heads are arranged as shown in FIGS. 1(^) to (C), vapor deposition is performed on the end face of the ejection port and a small area within the ejection port. Therefore, a thin film is substantially formed only on the surface by vapor deposition, without requiring any treatment such as providing filling oil inside the discharge port.

Here, giving directionality to the flow of the evaporated gas can be achieved by, for example, increasing the distance between the evaporation source and the end face of the ejection port involved in evaporation under a high vacuum of 1 G-'Torr or more. As the heating source, a resistor boat and an electron beam are used. In addition to the vapor deposition method, the surface layer 12 can also be formed using, for example, a sputtering method under a low vacuum. In this case, if a slit or orifice is provided, the directionality can be imparted to the ejected target material. can give.

When performing vapor deposition on the end face of the discharge port, the axis N in Fig.
Thin film formation can be uniformly performed by rotating the head stepwise or continuously around +.

Here, the substance used for vapor deposition etc. is metal.

All substances commonly used in vapor deposition, such as metal oxides, nitrogen compounds, and organic compounds, can be used. Atoms include /J2, Sb, As, Ba, Di, and Cd.

Cr, Go, Cu, 8u, Fe, Pb, Mg, Mn, N
i, Se, Si, Ag, Ti, Zn.

Sn, Ta, Mo, W, Ph, In, Ge, Te, etc., and other compounds of these atoms, halides,
Nitride is used. Also high melting point organic compounds, organic pigments such as copper phthalocyanine, perylene, quinacridone, tetrafluoroethylene, polyethylene.

A polymeric compound such as Boppara phenylene sulfide is used.

The head on which the surface layer 12 has been formed in this manner may then be subjected to a treatment for improving durability, such as annealing or passivation, if the layer 12 is made of metal. The film thickness when forming the coating layer by vapor deposition is preferably in the range of 500 μm to 10 μm.

In addition, if you want to improve the surface shape, so-called flattening, the film thickness should be large, but if you only want to make the wettability uniform for ink, you can achieve the desired effect even if the film thickness is small. .

(Example) For example, as shown in Fig. 1 (B), Fig. 2, and Fig. 3,
Cr was deposited by electron beam on a head provided with a heating element as disclosed in Japanese Patent No. 5-128470 while rotating the head around the N1 axis with θ=70°. The thickness of the Cr layer after vapor deposition was 0.5 μm. Due to this vapor deposition, no Cr was attached inside the discharge port 6.

(Printing test) Using this head, the following conditions signal pulse condition applied pulse width, 10μSeC pulse frequency; Parts by weight Diethylene glycol 26 parts by weight Direct Black 1544 parts by weight When an ink ejection experiment was carried out, stable ejection and excellent recording with high impact point accuracy could be performed over 10 times or more.

The surface layer described above is formed by adhering to the end surface of the discharge port after it is formed, so the end surface after the discharge port is formed may remain the rough surface that was used during processing, or the accuracy during processing may deteriorate. Even if the end face is formed at an angle to the center line of the discharge due to a defect, the uneven end face shape can be corrected by the subsequent coating layer, and the end face can be made smooth or perpendicular to the center line of the discharge. It can be corrected on the surface. Alternatively, even if the end face of the ejection port is finished in a smooth state, it is possible to finish the surface into an arbitrary roughened state when coating it. In other words, it becomes possible to form a uniform surface and to arbitrarily process the surface shape of the end face of the ejection port.

Therefore, in the inkjet recording head having the surface treated by the method according to the present example, the end face of the ink ejection port will not be unevenly wetted by ink, and the ejection direction of the ink droplets will be as shown in FIG. 4(A). Therefore, it becomes possible to obtain an excellent print quality.

[Effects of the Invention] As explained above, according to the present invention, the inside of the ejection port can be masked or surface treated regardless of the principle of ejection energy generation and the nozzle form, and regardless of the head material. Surface treatment can be performed easily and reliably without requiring complicated processes such as careful cleaning afterwards. Furthermore, the surface and vicinity of the ejection port of the head are made of uniform material and smoothed, thereby making it possible to obtain stable ejection operation and high printing quality. Furthermore, the finish of the head ejection port surface and nearby surfaces is stabilized, and product variations in mass production are significantly reduced. In addition, the range of selection of materials used for surface treatment is widened, and highly durable materials can be used as appropriate, making it possible to extend the life of the recording head.

[Brief explanation of the drawing]

1 (A), (B) and (C) are schematic cross-sectional views showing three examples of inkjet recording heads to which the method of the present invention can be applied, and FIGS. 2 and 3 are respectively FIG. 11) are a perspective view and a front view of the recording head, and FIGS. 4(A) and 4(B) are side sectional views for explaining the ink droplet ejection state of the inkjet recording head. DESCRIPTION OF SYMBOLS 1... First substrate, 2... Surface layer, 3... Discharge nozzle wall, 4... Second substrate, 5... Adhesive layer, 7... Ink, 8... Ink Droplet, 9... End face of ejection port, lO... Nozzle pipe or nozzle wall, 12... Surface layer, 16... Ink channel. Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In a surface treatment method for an inkjet recording head that performs surface treatment by depositing a substance on an end face including an ink ejection opening of an inkjet recording head, the substance is ejected from a direction oblique to the normal line of the ejection opening. A method for surface treatment of an inkjet recording head, characterized in that the surface treatment method for an inkjet recording head is applied to the end surface.