JPS62201257A - Liquid jet recording head - Google Patents

Abstract

PURPOSE:To obtain a liquid jet recording head capable of performing gradation recording with always stable emitting capacity, by laminating a plurality of electrothermal converters. CONSTITUTION:In a liquid jet recording head having an electrothermal converter equipped with emitting orifices for emitting a recording liquid, the liquid passages communicating with said emitting orifices, a heat generating resistor layer and at least a pair of electrodes electrically connected to said heat generating resistance layer, a plurality of electrothermal converters are laminated. By laminating a plurality of electrothermal converters on a substrate, the distance between the emitting orifice and the indivisual electrothermal converter is held equally. Even if a heat acting surface changes by the selection or combination of the electrothermal converters, the resistance of a fluid at the time of the emission of a liquid droplet does not change and, therefore, stable emitting capacity is held to make it possible to perform gradation recording. Further, without allowing a plurality of the electrothermal converters to occupy a wide place, said electrothermal converters can be easily received in one nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to a liquid jet recording head, and more particularly to a liquid jet recording head capable of performing gradation recording by ejecting recording liquid in the form of droplets.

[Prior Art] Conventionally, non-impact recording methods have attracted attention because the noise generated during recording is so small that it can be ignored. Among these, the liquid jet 01 recording method (inkjet recording method) is an extremely powerful recording method that enables high-speed recording and can record on plain paper without the need for special processing such as fixing. Various methods are being proposed and efforts are being made.

Among them, for example, JP-A-54-51837 and )
・The method described in DO, S) No. 2843064 is superior to others in that it applies thermal energy to a liquid to obtain the original force that causes the recording liquid to be ejected as droplets. Infusiera 1 - Recording method and CJ
They have different characteristics.

In other words, in the force equation No. 1j disclosed in the above-mentioned publication, the liquid under the action of thermal energy undergoes a state change accompanied by a sharp increase in volume, including the generation of bubbles, and the state change The acting force based on this causes the recording liquid to be drawn out as a droplet from the orifice at the tip of the recording head, and land on the recording target part 131 to perform recording.

Furthermore, the inkjet recording method disclosed in DOIS 28430 [i4 is extremely effective in applying the so-called drop-on demand recording method, and a part of the recording spatula 1 is a full line type with a high-density multilayer printer. The use of a di-orifice has the advantage that high-resolution, high-quality images can be obtained at high speed.

In this way, liquid jet recording devices have many advantages, but in order to record images with even higher resolution and higher quality, it is necessary to give recording pixels gradation characteristics and create halftones. It is necessary to record images that include information on

However, conventionally, such image recording devices have gradation control++
In the first method, a pixel is formed by a plurality of cells arranged in a matrix, each having an image forming element body, and the image formed in the cells formed in the form of a 71-ix element. A desired level of gradation is digitally expressed in accordance with the number of cells occupied by the image forming element and their arrangement. In the second method, each pixel is formed by an individual image forming element, and by changing the optical density of the image forming element, desired gradation is expressed in an analog manner.

However, in the liquid jet recording spatula I~, which performs recording by drawing liquid out using thermal energy, according to the first gradation control method, the area of each pixel itself becomes large, leading to a decrease in clarity, etc. Easy to use. Furthermore, because it is digitally controlled, the gradation steps are coarse, and the image quality lacks precision. Furthermore, in the gradation control force type, the size of one pixel, that is, the size of the image forming element, is generally changed by changing the electric energy applied to the energy generator to change the size of the ejected droplet. However, this method has problems in that the gradation control range is narrow and a sufficient gradation control range cannot be obtained, and that ejection failures of the recording head tend to occur, leading to a decrease in reliability.

Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 55-132259, a plurality of heat generating elements are arranged in series in the discharge direction inside the nozzle, and the number of operating elements is varied to increase the heat action area. A recording head has been proposed in which the bubble volume is modulated by increasing or decreasing the bubble generation area.

Furthermore, in the method disclosed in Japanese Patent Application Laid-Open No. 55-73568, two or more heating elements with different heating element areas are arranged in the discharge direction in the nozzle, and one appropriate heating element is generated according to a human power signal. The selected dot diameter is made variable and the gradation is controlled.

That is, in the recording head as described above, a plurality of heating elements are arranged in the nozzle in the ejection direction, and by selecting or driving a plurality of these heating elements in combination, the area of heat action is changed and the dot diameter is changed. I was doing gradation.

However, as mentioned above, when multiple heating elements are arranged in the nozzle in the discharge direction, the relative distance between the heating element and the nozzle outlet changes depending on the heating element selected, and due to physical conditions. There is a risk that the ejection performance may change. Specifically, the distance from the end of the heating element on the ejection port side to the ejection port has a significant impact on the ejection performance due to changes in fluid resistance, etc. In some cases, the ejection performance differs depending on the selection of the heating element.

Furthermore, as the number of heating elements increases, it becomes difficult to fit them all into the nozzle, so that the area and number of heating elements tend to be limited.

[Problems to be Solved by the Invention] An object of the present invention is to provide a liquid jet recording head that can eliminate the above-mentioned conventional drawbacks and perform gradation recording with always stable ejection performance. .

Means for Solving Problem E 1 In order to achieve the above object, the present invention provides an outlet for discharging recording liquid, a liquid path communicating with the outlet [-1], and a heat generating An electrothermal transducer comprising a resistance layer and at least one electrode electrically connected to the heating resistance layer.
The recording head is characterized in that a plurality of electrothermal transducers are laminated.

[Function] The liquid jet recording head of the present invention has a plurality of electrothermal transducers laminated on the substrate, so that the distance between the Tagawa orifice and each electrothermal transducer is kept equal; Even if the thermal action area changes due to the selection or combination of electrothermal converters, the fluid resistance that occurs during droplet ejection does not change, so stable ejection performance is maintained and gradation recording is possible. Moreover, a plurality of electrothermal transducers can be easily accommodated in one nozzle without occupying a large space.

[Example] Hereinafter, an example of the present invention and its manufacturing process will be specifically described based on the drawings.

1 to 3 show an embodiment of the present invention. Here, 1
For example, this is a wafer obtained from a medium-crystalline silicon ingot, and a silica (Si02) layer 10 having a thickness of about 3 μm is formed on the S1 wafer 1 by thermal oxidation. Then, on the layer 10, a first heat generating resistor layer 11 made of hafnium boride with a thickness of 1ul12 or about 02 μm is formed by, for example, a microwave electron cyclotron resonance sputtering method using a magnetron. After forming the first electrode layer 12 of aluminum with a thickness of approximately 0.2 μm, the first electrodes 128 and 12B are formed by photolithography, and the heat generating area is approximately 10 μm.
A first heater IIA of 0 μm x 150 μm is patterned.

Next, silica 5i02 is deposited to a thickness of about 0.2 μm by bias sputtering, for example, or, what is important here, the insulating layer of silica 5i02 that is formed is then formed in a stacked form one after another. When the edges of the heater are no longer uneven, foaming from the heat acting surface becomes stable.

Therefore, in this example, the length of the heater in the discharge direction is kept constant, and the insulating layer formed between the lower heaters is kept as flat as possible. Reference numeral 13 indicates the first
The insulating layer is shown.

Once the first electrode 12B and the first heater 118 are covered with the insulating layer 13, the same procedure and method are repeated to cover the second electrode 22A.
and 22B are made of 11fB2 with a thickness of about 0.2 μm, and the second heater 218 is made of aluminum with a thickness of about 0.2 μm. In this case, the second heater 218 is patterned with a width of about 50 μm. , silica 5 with a thickness of about 02 μm
Cover with a second insulating layer 23 of i02.

Then, roughly connect the third electrodes 328 and 32B to about 0.
The third heater 318 is made of aluminum with a thickness of about 2 μm and an area of about 25 μm.
A first protective layer 33 is formed using 5i silica by bias sputtering.
02 with a thickness of approximately 0.6 μm. Reference numeral 34 denotes a second protective layer, which is formed of tantalum Ta to a thickness of approximately 0.3 μm by microwave electron cyclotron resonance sputtering using a magnetron. In FIG. 2, 21 and 31 are respectively a second heating resistance layer and a third heating resistance layer, and 22 and 32 are respectively a second electrode layer and a third electrode layer.

- For the substrate constructed by the process described in ``-'', a liquid passage not shown or provided with an orifice;
A liquid jet recording head was constructed by providing a liquid chamber, a liquid supply system, etc. Thus, the first electrode +2A, 12B and the second electrode 22A, 22B of the recording head configured in this way
By supplying pulse signals to the third electrodes 328 and 32B, it was possible to obtain recordings using droplets having diameters as shown in Table 1.

As is clear from Table 1, we were able to obtain discharge characteristics that were approximately proportional to the action area of the heater without any large changes in the dispensing speed or frequency characteristics. Orifice to individual heater II, 2LA
, 3+A is kept constant.

Table 1 Note that in the above explanation, an example was described in which three heaters were stacked, but the number of heaters is not limited to this, and it is of course possible to increase or decrease the number as necessary. It is.

Furthermore, the size of the heater can be appropriately selected, and the size can also be made different. Furthermore, it goes without saying that it is possible to select one heater from these heaters or to use a combination of multiple heaters at the same time.[Effects of the Invention] As explained above, the present invention According to the invention, a plurality of electrothermal transducers/layers are formed on the substrate in the nozzle with an insulating layer interposed therebetween, so that the distance from the nozzle orifice to the electrothermal transducers is kept constant. By keeping the ejection performance stable, it became possible to achieve accurate gradation recording.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing an example of the configuration of an electrothermal converter on a substrate in the liquid jet-recording head of the present invention, FIG. 2 is a sectional view taken along the line A-B in FIG. 1, 1... Wafer, 10... Silica layer, +1, 21.31... Resistance layer, 12.22.32... Electrode layer, 11^, 218, 31A... Heater, +2A, 128
, 22A, 22B, 32^, 32B... electrode, 13.
23... Insulating layer, 33.34... Protective layer.

Claims (1)

[Scope of Claims] The recording liquid includes an ejection port for ejecting a recording liquid, a liquid path communicating with the ejection port, a heat-generating resistive layer, and at least one pair of electrodes electrically connected to the heat-generating resistive layer. A liquid jet recording head having an electrothermal transducer, characterized in that a plurality of the electrothermal transducers are stacked.