JPH02162051A - Liquid jet recorder - Google Patents

Abstract

PURPOSE:To prevent the corrosion of an exothermic layer, which is caused by recording liquid, and to enhance the durability of a recording head by laminating noble metal coating on the recording liquid contact surface of a thermal energy acting part. CONSTITUTION:An Si substrate 101 is spattered with SiO2 as a lower layer 102 of a 5-mum thickness, with TaSiO2 of 400Angstrom as an exothermic resistant layer 103, and with Al of 5,000-Angstrom thickness as an electrode 104 of a desired shape, in order from the bottom. SiO2 is spattered in a 5,000-Angstrom thickness as a 1st protective layer 105, and moreover an Au layer 106 is spattered in a 2,000-Angstrom thickness. Polyimide resin is patterned as a 2nd protective layer 107 on the surface except the heat acting surface 108 to form a heater board. A photosensitive dry film 33mum in thickness is laminated on the heater board, a desired pattern mask is exposed and developed to form the walls of an ink chamber and channel. Thus, noble metal is laminated on the thermal energy acting part to enhance the durability of the recording head.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid jet recording device, and more particularly to a recording head for a bubble jet printer.

The non-impact recording method for assisting in death is v! , in that the noise generated during recording is extremely small to the extent that it can be ignored.
It has been attracting a lot of attention recently. Among these, the so-called inkjet recording method, which enables high-speed recording and can record on so-called plain paper without the need for special fixing processing, is an extremely powerful recording method, and various methods have been used to date. Some have been proposed and improved and commercialized, while others are still being worked on to put them into practical use.

Such an inkjet recording method performs recording by causing droplets of a recording liquid called ink to fly and adhere to a recording member.

There are several types of methods depending on the method of generating recording liquid droplets and the control method for controlling the flying direction of the generated recording liquid droplets.

First, the first method is the one (Tale type method) disclosed in, for example, US Pat. Recording is performed by controlling the droplets with an electric field in accordance with a recording signal to selectively attach recording liquid droplets onto a recording member.

To explain this in more detail, an electric field is applied between the nozzle and the accelerating electrode to eject a negatively charged recording liquid droplet from the nozzle, and the ejected recording liquid droplet is converted into a recording signal. Accordingly, the droplet is caused to fly between x and y deflection electrodes configured to be electrically controllable, and the droplet is selectively deposited on the recording member by changing the intensity of the electric field to perform recording.

The second method is a method (Sweet method) disclosed in, for example, U.S. Pat. No. 3,596.275, U.S. Pat. By generating droplets of recording liquid and flying the generated droplets with a controlled amount of charge between deflection electrodes to which a negative electric field is applied,
It records on a recording member.

Specifically, the orifice (discharge port) of a nozzle, which is a part of the recording head to which the piezo vibrating element is attached.
A charged electrode configured to have a recording signal applied thereto is arranged at a predetermined distance in front of the piezo vibrating element, and an electric signal of a constant frequency is applied to the piezo vibrating element to mechanically vibrate the piezo vibrating element, A small droplet of recording liquid is ejected from the ejection port. At this time, charges are electrostatically induced in the recording liquid droplet discharged by the charging electrode, and the droplet is charged with an amount of charge corresponding to the recording signal. When a droplet of recording liquid with a controlled amount of charge flies between deflection electrodes to which a constant electric field is uniformly applied, it is deflected according to the amount of charge applied.
Only the droplets carrying the recording signal are allowed to deposit on the recording member.

The third method is, for example, the method disclosed in U.S. Pat. No. 3,416,153 (Hertz method),
In this method, an electric field is applied between a nozzle and a ring-shaped charged electrode, and small droplets of recording liquid are generated and atomized using a continuous vibration generation method to perform recording. That is, in this method, the atomization state of droplets is controlled by modulating the electric field intensity applied between the nozzle and the charging electrode in accordance with the recording signal, and the gradation of the recorded image is produced.

The fourth method is, for example, the method disclosed in US Pat. No. 3,747,120 (Stemme method), and this method is fundamentally different in principle from the above three methods.

That is, in all three methods, the droplets of recording liquid ejected from the nozzle are electrically controlled while they are in flight, and the droplets carrying the recording signal are selectively attached to the recording member. In contrast, this Stemme method
Recording is performed by ejecting small droplets of recording liquid from an ejection port in response to a recording signal.

In other words, the Stemme method applies an electrical recording signal to a piezo vibrating element attached to a recording head that has an ejection port for discharging recording liquid, and converts this electrical recording signal into mechanical vibration of the piezo vibrating element. In this method, recording is performed by ejecting small droplets of recording liquid from the ejection opening according to the mechanical vibrations and adhering them to the recording member.

These four conventional methods each have their own advantages, but there are also points that can be solved in the other method.

That is, in the first to third methods, the direct energy for generating droplets of the recording liquid is electrical energy, and the deflection control of the droplets is also electric field control.

Therefore, although the first method is simple in structure, it requires a high voltage to generate droplets, and it is difficult to use a multi-nozzle recording head, making it unsuitable for high-speed recording.

The second method allows the recording head to have multiple nozzles and is suitable for high-speed recording, but it has a complicated structure, and the electrical control of recording liquid droplets is sophisticated and difficult, and satellite dots are placed on the recording member. There are problems such as easy occurrence of.

The third method has the advantage of being able to record images with excellent gradation by atomizing recording liquid droplets, but on the other hand, it is difficult to control the atomization state and fog occurs in the recorded image. In addition, it is difficult to create a multi-nozzle recording head.
There are various problems such as being unsuitable for high-speed recording.

The fourth method has relatively many advantages compared to the first to third methods. In other words, the structure is simple, and since recording is performed by ejecting recording liquid from the ejection opening of the nozzle on-demand, it is possible to reduce the number of small droplets that fly as in the first to third methods. Second, it is not necessary to collect droplets that are not needed to record an image, and unlike the first and second methods, there is no need to use a conductive recording liquid, and the material of the recording liquid is It has great advantages such as a high degree of freedom. On the other hand, it is difficult to make the recording head multi-nozzle because there are problems in processing the recording head, and it is extremely difficult to miniaturize the piezoelectric vibrating element having the desired resonance number. This method has drawbacks such as that it is not suitable for high-speed recording because the recording liquid droplets are ejected and ejected in flight using the mechanical energy of the mechanical vibration of the piezoelectric vibrating element.

Furthermore, Japanese Patent Application Laid-Open No. 48-9622 (corresponding to the above-mentioned US Pat. No. 3,747,120) discloses, as a modification,
It is described that thermal energy is used instead of using mechanical vibration energy by means such as the piezo vibration element described above.

That is, the above-mentioned publication describes a so-called bubble jet liquid jet recording device that uses a heating coil that directly heats liquid as a pressure increasing means instead of a piezo vibrating element to generate steam that causes a pressure increase. There is.

However, in the above publication, the liquid ink in the bag-shaped ink chamber (liquid chamber), which has only one opening through which liquid ink can go in and out, is directly heated and vaporized by energizing the heating coil as a pressure increasing means. However, when discharging liquid continuously and repeatedly, it is not clear how to heat it.
There is no suggestion whatsoever.In addition, the heating coil is located at the deepest part of the bag-shaped liquid chamber, far from the liquid ink supply path, so the head structure is complicated. In addition, for continuous repeated use at high speeds,
It is not suitable.

Moreover, with the technical content described in the above-mentioned publication, it is not possible to quickly prepare for the next liquid discharge after discharging the liquid using the generated heat, which is important in practice.

In this way, conventional methods have problems in terms of structure and high-speed recording.

The use of multi-nozzle recording heads has advantages and disadvantages in terms of the generation of satellite dots and fogging of recorded images, and there is a restriction that it can only be applied to applications that take advantage of these advantages.

Furthermore, Japanese Patent Application Laid-Open No. 59-194866 discloses that a first protective layer made of an inorganic insulating material and a second protective layer made of an organic material are provided on the electrode.
A recording head is described in which a first protective layer of an inorganic insulating material and a third upper layer of an inorganic material are laminated in this order on the heat generating portion. However, although many metal 9 alloys have been mentioned as materials constituting the third upper layer, it has not been clearly stated which material has the highest practical impact resistance. In addition, the third upper layer is intended only for anti-cavitation force,
There are drawbacks such as the fact that chemical resistance to recording liquids is not taken into account.

Purpose The present invention was made in view of the above-mentioned circumstances.
The durability of the recording head is improved by preventing deterioration of the heating layer due to the shock of the cavitation force generated on the heat-active surface when recording droplets are ejected, and corrosion of the heating layer J- by the recording liquid. The purpose of this invention is to provide a liquid jet recording device that has the following characteristics.

Structure In order to achieve the above-mentioned object, the present invention provides a thermal energy acting section that accommodates the introduced recording liquid, generates bubbles in the recording liquid by heat, and generates an acting force as the volume of the bubbles increases. an orifice connected to the flow path for ejecting the recording liquid as droplets by the acting force; and an orifice connected to the flow path for introducing the recording liquid into the flow path. In a liquid jet recording device comprising a liquid chamber and an introduction means for introducing recording liquid into the liquid chamber, at least on the thermal energy application part,
It is characterized in that a noble metal film is laminated on the recording liquid contact surface.

First, the principle of ink ejection using a bubble jet will be explained based on FIG. In the figure, 21 is a lid substrate, 2
2 is a heating element substrate, 27 is a selective (independent) electrode, 28 is a common electrode, 29 is a heating element, 30 is ink, 31 is a bubble, 32
is a flying ink droplet.

(a) is a steady state, in which the surface tension of the ink 30 and the external pressure are in equilibrium on the orifice surface.

In (b), the heater 29 is heated until the surface temperature of the heater 29 rises rapidly and boiling development occurs in the adjacent ink layer, and microbubbles 31 are scattered.

(c) shows a state in which the adjacent ink layer that is rapidly heated on the entire surface of the heater 29 is instantaneously vaporized to form a boiling film, and the bubbles 31 grow. At this time, the pressure inside the nozzle increases by the amount of bubble growth, and the balance with the external pressure on the orifice surface is lost, causing an ink column to begin to grow from the orifice.

(d) shows a state in which the bubble has grown to its maximum, and ink 30 corresponding to the volume of the bubble is pushed out from the orifice surface. At this time, no current is flowing through the heater 29, and the surface temperature of the heater 29 is decreasing. The maximum value of the volume of the bubble 31 is slightly delayed from the timing of electric pulse application.

(e) shows a state in which the bubbles 31 are cooled by ink or the like and begin to contract. At the tip of the ink column, it moves forward while maintaining the extruded speed, and at the rear end, the ink flows backward from the orifice surface into the nozzle due to the decrease in nozzle internal pressure as the bubbles contract, creating a constriction in the ink column. .

In (f), the air bubbles 31 are further contracted, the ink comes into contact with the heater surface, and the heater surface is cooled even more rapidly. At the orifice surface, the external pressure is higher than the nozzle internal pressure, so the meniscus is largely moving into the nozzle. The tip of the ink column becomes a droplet and drops 5 to 1 droplets toward the recording paper.
It is flying at a speed of 0m/sec.

In (g), the air bubbles have completely disappeared in the process of refilling the orifice with ink by capillary action and returning to the state of (a).

FIG. 5 is a perspective view of the bubble jet recording head, and FIG. 6 is an exploded configuration diagram of the recording head, in which (a) is the lid substrate, (b)
7 is a back view of the lid substrate shown in FIG. 6(a). In FIG. 1, 23 is a recording liquid inlet;
4 is an orifice, 25 is a flow path, and 26 is a region for forming a liquid chamber.

FIG. 8 is a partial view of the bubble jet liquid jet recording head, (a) is a front partial view seen from the orifice side, (b)
) is a partial view taken along the - dotted chain line XX in (a).

The recording head 41 shown in FIG. 8 has a predetermined number of grooves of a predetermined width and depth at a predetermined linear density on a substrate 43 on which an electrothermal transducer 42 is provided on the back surface. By joining the grooved plate 44 so as to cover the substrate 43,
It has a structure in which a liquid discharge part 46 including an orifice 45 for causing liquid to fly is formed.

The liquid discharge part 46 has a heat acting part 47 where the thermal energy generated by the orifice 45 and the electrothermal converter 42 acts on the liquid to generate bubbles and cause a sudden change in state due to expansion and contraction of the volume. and has.

The heat acting part 47 is located above the heat generating part 48 of the electrothermal converter 42, and has a heat acting surface 49, which is a surface of the heat generating part 48 that comes into contact with the liquid, as its lower surface. The heat generating section 48 is
A lower layer 50 provided on the base body 43, a heating resistance layer 51 provided on the lower layer 50. It is composed of an upper layer 52 provided on the heating resistance layer 51.

The heating resistance layer 51 is provided with electrodes 53 and 54 on its surface for supplying electricity to the core layer 51 in order to generate heat, and the heating resistance layer between these electrodes allows the heat generating portion 4
8 is formed.

The electrode giant 3 is an electrode common to the heat generating section of each liquid discharging section, and the electrode 54 is a selection electrode for selectively generating heat in the heat generating section of each liquid discharging section. It is provided along the liquid flow path.

The layer 52 isolates the heat generating resistor layer 51 from the liquid in the liquid discharge part 46 in order to chemically and physically protect the heat generating resistor layer 51 from the liquid used, and also provides a connection between the electrodes 53 and 54 through the liquid. It has the protective function of the heating resistance layer 51 to prevent short circuits.

The upper layer 52 has the above-mentioned functions, but
If the heat generating resistor layer 51 is liquid resistant and there is no need for an electrical short circuit between the electrodes 53 and 54 through the liquid, it is not necessarily necessary to provide it, and the surface of the heat generating resistor layer 51 may immediately come into contact with the liquid. It may be designed as an electrothermal converter with a structure that

The lower layer 50 has a heat flow control function, that is, during droplet ejection, the heat generated in the first heat generating resistor layer 51 is transferred to the substrate 43.
The proportion of conduction toward the heat-effecting portion 47 side is increased as much as possible than the conduction toward the side, and after the droplet is ejected, that is, after the electricity to the heat-generating resistor layer 51 is turned off, the heat-effecting portion 4
7 and the heat generating part 48 is quickly released to the substrate 43 side, and the liquid in the heat acting part 47 and the generated bubbles are rapidly cooled.

Useful materials for forming the heating resistor 51 include, for example, a tantalum-3un2 mixture, tantalum nitride, nichrome, and a silver-palladium alloy.

Silicon semiconductors, hafnium, and lanthanum.

Examples include borides of metals such as zirconium, titanium, tantalum, tungsten, molybdenum, niobium, chromium, and vanadium.

Among the materials constituting these heating resistors 51, metal borides are particularly excellent, and among them, hardened hafnium has the best properties.
Next, zirconium boride.

The order is lanthanum boride, tantalum boride, vanadium boride, and niobium boride.

The heating resistor 51 can be formed using the above-mentioned materials using methods such as electron beam evaporation and sputtering. What is the thickness of the heating resistor 51?

In order to achieve the desired amount of heat generated per unit time, it is determined according to the area, material, shape and size of the heat-acting part, as well as actual power consumption, etc. 1. In the normal case, 0.001-5 μm, preferably 0.01-1
It is assumed to be μm.

As the material constituting the electrodes 53 and 54, many commonly used electrode materials can be effectively used, and specific examples include AQ, Ag, AntPt, Cu, etc. It is provided at a predetermined location with a predetermined size, shape, and thickness using a method such as vapor deposition.

The characteristics required of the protective layer 52 are to protect the heat generating resistor 51 from the recording liquid without preventing the heat generated by the heat generating resistor 51 from being effectively transferred to the recording liquid. Examples of useful materials for forming the protective layer 52 include silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, and zirconium oxide, which can be prepared using techniques such as electron beam evaporation and sputtering. It can be formed by The thickness of the protective layer 52 is usually 0.01 to 10 μm, preferably 0.1 to 5 μm, and most preferably 0.1 to 3 μm.

As described above, conventionally, the protective layer has played the role of effectively transmitting the generated heat to the recording liquid and protecting the heat generating resistor layer. However, since the protective layer is in direct contact with the recording liquid, this contact surface (thermal action surface 49) receives the force of cavitation that occurs when the droplets are ejected.

When this cavitation force repeatedly shocks the surface of the protective layer, it causes defects such as cracks in the protective layer, which reduces the coverage of the protective layer and significantly shortens the life of the heat generating part. becomes.

Therefore, it is necessary to prevent the heating resistance layer from being affected by shock from this cavitation force on the surface that comes into contact with the recording liquid.

Therefore, the present invention is characterized in that it attempts to prevent the influence of the cavitation force by providing a noble metal layer for reinforcing mechanical strength on the contact surface with the recording liquid.

In the present invention, the noble metals chemically refer to copper, silver, and gold in group Ⅰ of the periodic table, mercury and platinum group elements in group Ⅰ, but copper and mercury have chemical resistance (ink resistance) or film resistance. Since they are difficult to form, they are excluded here, and the discussion is limited to gold, silver, and platinum group elements, which are generic terms in the shell. That is, Au, A
g, Ru.

Rh, Pd, Os, Ir, and Pt. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a diagram for explaining an embodiment of a liquid jet recording apparatus according to the present invention, and is a configuration diagram of a heat acting section of a recording head. In the figure, 101 is a Si substrate, 102 is a lower layer, 1
03 is a heating resistance layer, 104 is an electrode, 105 is a first protective layer, 106 is an Au layer, 107 is a second protective layer, and 108 is a heat acting surface.

5μ of Si is deposited as the lower layer 102 on the Si substrate 101.
After sputtering with a thickness of m.

Using photolithography technology, etching technology, sputtering technology, etc., a desired shape was formed using Ta-8iO as the heat generating resistive layer 103 and AQ as the electrode 104 with a thickness of 400 times.

Next, as the first protective layer 105, 50 SiO,
Sputtering with a thickness of 0.00 and more.

Sputter the Au layer 106 to a thickness of 2000 nm.

As a second protection W1107, a polyimide resin was patterned on a portion other than the heat acting part 108 to form a heater board. A photosensitive dry film with a thickness of 33 μm is laminated on the heater board, and the walls of the ink chamber and flow path are formed by blocking and developing the film using a desired pattern mask. This was then cut using a slicer to form a discharge port.

The first protective layer 105 is not limited to silicon oxide, and may be made of an inorganic nitride material or an inorganic oxidized material used in the conventional protective layer 52 shown in FIG. 8.

The second protective layer 107 is used to protect parts other than the heat-active surface 108, and is intended to prevent liquid immersion and improve liquid resistance. In addition to polyimide resin, examples of materials constituting the second protective layer 107 include silicone resin, fluororesin, epoxy resin, and phenol resin.

Further, in the embodiment of the present invention, an Au layer was formed by sputtering on the heat-active surface 108 on the upper part of the first protective layer 105, but the same effect can be obtained by forming not only the Au layer but also other noble metals. is obtained. In addition to sputtering, the film can be easily formed by known methods such as plating and vapor deposition.

FIG. 9 shows an Au layer 1 formed using photolithography.
The pattern No. 06 is shown as the right hatched area, and the second protective layer 107 is shown as the left hatched area. In addition, the heat acting surface 108 in this case has a width of 30 mm with respect to the flow path direction.
μm, and the length is 132 μm.

Note that the Au layer 106 is not limited to the heat acting surface 108;
As shown in FIG. 2, it may be laminated all over the flow path including the electrode 104.

Further, as shown in FIG. 3, the Au layer 106 is
It may be laminated not only on the 0B but also on the recording liquid contact surface in the vicinity thereof.

10 and 11 are conventional examples shown for comparison with the embodiment of the present invention, in which 111 is a Si substrate;
112 is a lower layer, 113 is a heating resistance layer, 114 is an electrode,
115 is a first protective layer, 116 is a second protective layer, 117
118 is a resin layer, and 118 is a heat acting surface. The difference from FIG. 1 is that the portion of the heat acting surface 118 that comes into contact with the recording liquid is the first protective layer 115, and the other shapes, configurations, and materials are exactly the same. Further, the shaded area represents the second protective layer 116.

The present inventors actually manufactured the embodiment shown in FIG. 1 and the comparative example shown in FIG. 10, and conducted a durability test on both, and found that droplet ejection was stable.

The number of times in which the recording droplet velocity was 5 to 1o111/s and there were no satellites was ejected was about 10' times in the conventional example, whereas in the embodiment of the present invention it was 109 times. By laminating precious metals in the thermal energy application area in this way, it was possible to dramatically improve the durability of the recording head.

As is clear from the above description, according to the present invention, since the noble metal is laminated on the recording liquid contact surface in the thermal energy acting section, it has excellent impact resistance.

Deterioration of the heat generating layer due to cavitation force can be prevented, and by protecting it with a chemically stable noble metal, corrosion by the recording liquid can be prevented, so the durability of the recording head can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of a liquid jet recording apparatus according to the present invention, and is a configuration diagram of a heat acting section of a recording head, and FIG. 2 is a diagram showing another embodiment of the present invention. Figure 3 shows
A diagram showing another embodiment of the present invention, FIG. 4 is a diagram showing the principle of bubble jet ink ejection from the recording head and bubble generation/disappearance.
5 is a perspective view of the recording head, FIG. 6 is an exploded configuration diagram of the recording head, where (a) shows the lid substrate, (b) shows the heating element substrate, and FIG. (a) Back view of the lid substrate,
FIG. 8 is a partial view of the recording head, (a) is a front partial view seen from the orifice side of the head, and (b) is an X-
It is a partial X-ray section view. FIG. 9 is a diagram showing the pattern of the Au layer according to the embodiment of the present invention in FIG. 1, and FIGS. 10 and 11 are diagrams showing the structure and pattern of the conventional heat acting section. 101...Si substrate, 102...lower layer, 1o3.
...Heating resistance layer, 104... Electrode, 105... First
protective layer. 106-AuJm, 107-Second Protection, I#, 10
8...Heat action surface. Figure 1 Figure 4 Figure 2 (C) 30 pieces;: (d) 喀=: <e) Cζ:: Figure 5 Figure 3 Figure Figure 2 (Q) Cb)

Claims (1)

[Claims] 1. A flow path that accommodates the recording liquid to be introduced and is provided with a thermal energy acting section that generates bubbles in the recording liquid using heat and generates an acting force as the volume of the bubbles increases; an orifice in communication with which the recording liquid is ejected as a droplet by the acting force; a liquid chamber in communication with the flow path and with which the recording liquid is introduced into the flow path; and a recording liquid in the liquid chamber. What is claimed is: 1. A liquid jet recording apparatus comprising an introducing means for introducing a liquid jet, wherein a noble metal film is laminated on a contact surface of the recording liquid at least on the thermal energy application section.