JPS5931944B2 - liquid jet recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid jet recording method in which recording is performed by jetting a liquid and forming flying droplets.

Non-impact recording methods have recently attracted attention because the noise generated during recording is so small that it can be ignored.

Among these, the so-called inkjet recording method (liquid jet recording method), which is capable of high-speed recording and can record without the need for special processing such as fixing on so-called plain paper, is an extremely powerful recording method. Until now, various methods have been devised,
Some products have been improved and improved in quality, while others are still being put into practical use today. In this liquid jet recording method, recording is performed by causing droplets of a recording liquid called so-called ink to fly and adhere to a recording member, and the generation of droplets of the recording liquid is There are several types of methods depending on the method used to control the method and the flying direction of the generated droplets.

Among them, for example, USP3683212, USP37
The liquid jet recording method described in publications such as 4712O and USP 3946398 is a so-called drop method in which a droplet is ejected from an ejection orifice in response to a recording signal, and the droplet is attached to the surface of a recording member to perform recording. -ondema
nd recording method, which ejects only the droplets necessary for recording, and it is not necessary to provide special means for collecting or processing ejected liquid that is unnecessary for recording, and the device itself can be simplified and miniaturized. , has recently attracted particular attention because it is not necessary to control the flight direction of droplets ejected from an ejection orifice, and multicolor recording can be easily performed.

Furthermore, the present applicant has proposed a liquid jet recording method that uses a completely different principle of droplet formation from the liquid jet recording method described above.
This liquid jet recording method disclosed in No. 2-118798 is not only very effectively applied to the above-mentioned DrOp-on-demand recording method, but also
Since it is possible to easily realize a high-density multi-orifice recording head in a type, it has the characteristic of being able to obtain high-resolution, high-quality images at high speed.

These liquid jet recording methods are suitable for so-called multi-orifice recording in which a large number of orifices are arranged in an array to simultaneously record a predetermined width or a predetermined area, and are capable of high-speed recording.

In particular, the liquid jet recording method disclosed in Japanese Patent Application No. 118798/1983 is capable of obtaining discharge orifices at a high density of, for example, 16 or more per unit, with high precision, and is therefore highly effective.
It is not an eric recording scale, but can record images (photographs, drawings, etc.) at the same density as the resolution of the recorded image, and because the orifices can be arranged in the FulIIIine, the recording speed can be greatly improved. . However, DrOp-0ndema has many excellent points as mentioned above.
Even in the nd recording method, there are issues that need to be resolved in terms of stability of recording characteristics, ensuring high-quality recorded images, and stability during high-speed recording. In particular, Dr.
The Op-on-demand recording method is a so-called COn method in which liquid is jetted from an ejection orifice under pressure to form a liquid column, and a regular pulsating flow is applied to the liquid column to form droplets of uniform diameter.
Unlike the tenuOus recording method, droplets are ejected from the ejection orifice each time based on the input recording signal, and capillary action is used to replenish the missing liquid, so the stability of the liquid is improved. There are problems in the stable supply of droplets, droplet ejection efficiency, constant and stable formation of droplets with uniform shape and uniform diameter, droplet formation frequency (equivalent to the number of droplets ejected per unit time), etc. exists. For example, droplet ejection efficiency is determined by the fact that energy generated according to a recording signal input to an energy acting part communicating with the ejection orifice effectively acts on the liquid in the acting part, and based on this, the ejection orifice The improvement cannot be measured unless the droplet is ejected more faithfully in response to the recording signal and the energy loss in this case is minimized. The positional relationship of the orifice side end with the energy application section, the inflow port side end that communicates with the energy application section and has an inlet for supplying liquid to the energy application section, and the energy generated in the energy application section. It largely depends on the amount of energy, the size of the discharge orifice, etc. For example, the size of the discharge orifice is small, the cross-sectional area of the orifice side end is approximately equal to the size of the discharge orifice, and the length from the discharge orifice to the energy application part is such that the area of the discharge orifice is S. Time, J? If the length of the droplet is sufficiently long, the shape of the droplet ejected from the ejection orifice changes from a spherical shape to an elongated ellipsoid, depending on the level value of the recording signal, and sometimes resembles a star with a trailing tail. It also shows the shape.

In particular, in the case of a high-density multi-orifice recording head, it is necessary to have a flow path with a substantially constant cross-sectional area up to the discharge orifice, including the energy acting part, and the flow path is linear. , the above-mentioned phenomena are likely to occur. Therefore, although it depends on the physical properties of the liquid used, there are more opportunities for satellite droplets to be generated than in the above-mentioned continuous recording method, which hinders the improvement of recording quality.

In particular, the liquid jet recording method disclosed in Japanese Patent Application No. 52-118798 is prone to the above-mentioned problems because droplets are ejected based on changes in the thermal state of the liquid. It is necessary that these problems be resolved.

The present invention has been achieved based on the above points, and includes:
The main objective is to provide a recording method that dramatically improves recording characteristics, especially recording quality.

The recording method of the present invention is most suitable for the recording method disclosed in Drpp-On Demand, particularly in Japanese Patent Application No. 118798/1983, and can maximize its effects. The liquid jet recording method of the present invention includes an orifice side end with a discharge orifice at the tip, a thermal energy application section, and an inlet communicating with the energy application section to supply liquid to the section. A liquid jet recording method that uses a recording head having an inlet side end and uses thermal energy to fly the liquid jetted from the discharge orifice as droplets and attach them to the recording surface to perform recording. Wherein, when the area of the ejection orifice is S1 and the length of the end on the side of the orifice is L1, recording is performed while maintaining the distance between the orifice and the recording surface to be equal to or greater than VH and equal to or less than 50L1. That is.

The present invention will be specifically explained below with reference to the drawings, but in order to avoid the complexity of the explanation and to facilitate understanding of the present invention,
The recording method disclosed in the above-mentioned Japanese Patent Application No. 118798/1982 will be explained.

Accordingly, the present invention is not limited within the scope of the following description, but is described, for example, in US Pat.
It is also applicable to the DrOp-on-demand recording method described in publications such as SP3747l2O and USP3946398. First, in order to quickly understand the following explanation, the outline of the recording method disclosed in Special Application No. 52-118798 will be explained. FIG. 5 is a schematic perspective view illustrating the recording method disclosed in Japanese Patent Application No. 118798/1982.

In this illustrated example, the state of the recording liquid 103 introduced into the liquid chamber 102 from the introduction pipe 101 changes instantaneously in accordance with the heat generated by electricity in the electricity/thermal converter 104 attached to the liquid chamber 102. cause Note that the converter 104 is energized at 0N through the electrodes 105-1 and 105-2 connected thereto.
The FF generates heat in a pulsed manner.

Due to this change in the state of the recording liquid 103, the orifice 1
An acting force is applied to the liquid 103 on the 06 side, and as a result, the liquid 103 is ejected and flies as a droplet 107 from the orifice 106 and adheres to the recording material 110 such as paper, thereby causing recording to occur. be done.

The converter 104 is provided on a substrate 108, and a voltage based on a power source 109 is applied according to the recording signal, heat is generated according to the input signal, and recording corresponding to the input signal flies and adheres to the recording member 110. It will be done.

Although the state of the droplet is schematically shown in FIG. 1, the shape of the droplet is expressed in detail as shown in FIGS. 2A and 2B.

In FIG. 2a, 201 is a recording head, 203 is an orifice side end having an orifice 202 at its tip for ejecting droplets, and 204 is an energy application part.
It has an electric/thermal converter 206 that generates heat as energy for ejecting droplets when a recording signal is input, and 205 is connected to a conduit 208 from a liquid storage tank 207
Inlet 2 for supplying liquid 209 supplied via
10 at the end on the inlet side.

Reference numeral 211 indicates bubbles generated when the liquid in the energy application section 204 undergoes a sudden state change due to the action of heat generated by energizing the electricity/thermal converter 206 .

Now, as shown in the figure, when the converter 206 is energized and a sharp state change occurs in the liquid in the energy application section 204, and a droplet is ejected from the orifice 202, the orifice 206
The ejected droplet 212 in the vicinity of 2 is elongated and has a cross-sectional area corresponding to the area S of the orifice 202 and the orifice 202 and the converter 2.
06 (the length of the orifice side end) L1 or the length L2 of the converter 206 in the flow path force direction.

Therefore, if the flight distance is long, satellite droplets will inevitably be generated, and if the recording paper 213 is placed around P3, a recording as shown in FIG. 2, P3, will be made. Since the droplet 212 discharged from the discharge orifice 202 has an oblong shape as shown in the figure, separation occurs mainly due to its surface tension during flight, for example, as shown in the figure. When the droplet is separated into three parts as shown in FIG.
occurs. Each of the generated droplets 212-1, 212-2, 21
The motion speeds 2-3 vary depending on the situation, and may be the same speed or different speeds from each other. Therefore, if the position of the recording paper 213 is changed to, for example, Pl, P2, P3, droplets will adhere to the recording paper 213 in the states shown as P, , P2, P3, as shown in FIG. 2b. do. This kind of situation varies depending on the relationship between the flying speed of the droplets 212 and the speed of the recording paper 213. In particular, when performing high-speed recording, the recording paper 213 is lower than the flying speed of the droplets 212. It is noticeable when moving at high speed. Therefore, it is preferable that the recording paper 213 is placed at a distance away from the production orifice within a range where the generated droplets will not separate during flight and create satellite droplets. However, if the distance is too large or too small, it will have a big impact on the stability of recording characteristics such as image quality.In fact, whether or not satellite droplets will be formed depends on various factors related to droplet formation. It is thought to be based on a complex relationship between elements, and often relies on errors and errors.

Therefore, as a result of intensive research and consideration, the present inventor found that if the recording paper is positioned in relation to the area of the ejection orifice and the length of the orifice side end, especially in relation to the area of the ejection orifice, other factors It has been discovered that stable recording characteristics can almost always be obtained even when there are fluctuations in the recording characteristics.

In the present invention, the recording paper as a recording member has a discharge orifice having an area of V or more, preferably 2
The upper limit is the range in which satellite droplets do not occur, specifically, if the length of the orifice side end is L1, 50L1, preferably 40L1, The optimum value is 30L1.

In the present invention, in order to define the position of the recording paper from the ejection orifice within the above numerical range, we created hundreds of different recording heads and repeated various experiments for each, and from the results, we determined the above relationship. This is because it has been confirmed that if the positions of the ejection orifice and the recording paper are maintained based on the above, a recorded image of extremely high quality, high clarity, and high resolution can be obtained.

Incidentally, if the recording paper is placed at a distance shorter than J from the ejection orifice, disturbances in droplet flight and droplet generation will occur due to the movement of the recording, and in practice, such proximity It is extremely difficult to place the recording paper at a certain position and to protect that position at a constant level during recording. On the other hand, if the recording paper is placed at a distance greater than 50L1, the image quality will be disturbed, and especially when the recording paper is moved at a high speed, a so-called "raindrop" phenomenon will occur, in which the attached droplets will trail. Furthermore, in order to achieve the present invention more effectively, the lengths of Ll and L2 are also important.

That is, if the length of L is too long, the droplet ejection efficiency will be extremely reduced, and if the length of L1 is sufficiently small, there is a chance that a brushing phenomenon will occur when the liquid is ejected. Needless to say, a suitable value for L1 largely depends on the area S of the orifice. Specifically, V
? /π≦L1≦50J? It is more preferable in the present invention if the LI is designed to be 5 μm to 577 m, which is advantageous from a practical point of view.

The present invention will be described below with reference to Examples.

Example 51 After sputtering SiO2 to a layer thickness of 3 μm on a 11×10 alumina substrate soil, using a mask with a predetermined pattern, 1,000 pieces of HPB2 and 5,000 pieces of aluminum were laminated as heating elements (electricity/thermal converters). A pattern as shown in Figure 1 was created.

The shape of the heating resistor in this case is 40μMX5OOμm (
That is, L2=500 μm). 40μ as shown in Figure 1
MX4Oμm×5? A groove cover plate with grooves cut into it was glued so that the grooves and the heating element matched. In this case, the distance (L,) from the orifice to the heating element was 500 μm. A square wave of 40 volts is applied to this heating element at 500 volts with a pulse width of 10 μs.
When the force was applied repeatedly at a period of μs, a long and narrow liquid column force was ejected as shown in Figure 2a. The resistance of the heating element was 150 ohms, and the ink used was one in which black dye was dispersed in a solvent mainly composed of water. The flying speed of droplets is approximately 5m/s
ec, the moving speed of the recording paper is 01 m/Sec, and the recording paper is moved 1.5 times from the ejection orifice position, 251I!
When recording 11 and 30 days apart, each
In FIG. 2b, droplet adhesion states as shown by Pl, P2, and P3 were observed.

In this case, when the paper feed speed was reduced to 1/2, the state of P2 was improved to the state of P1. Next, in the same production process, the heating element shape is 40 μm x 100 μm (i.e. L2 = 100 μm)
, L1 = 100 μm 1 A sample was prepared which was the same as the above sample, and a 10 μs rectangular wave was repeatedly applied at a period of 500 μs. In this case, the applied voltage is 45 volts,
The resistance of the heating element was 750 ohms.

Also, is the distance between the recording paper orifice and the recording paper each 0.6? ，
57!1I! Installed at 1,6H111 position 1m/Se
I sent it by c.

The result at that time is shown in Figure 2b (7>Pl゜, p゜, PI3. In this case, by slowing down the paper feed speed,
? It was shown that it is possible to record in the state shown by P even if the distance is a certain degree. Note that the droplet ejection speed at this time was 2 m/Sec.

[Brief explanation of the drawing]

FIG. 1a is a schematic perspective view for explaining the prior art necessary for explaining the present invention, FIG. 1b is a plan view thereof, and FIGS. 2A and 2b are each FIG. 1 is a schematic explanatory diagram for explaining the present invention. 101...Introduction pipe, 102...Liquid chamber,
103...Liquid, 104...Electrical/thermal converter, 105...Electrode, 106...Discharge orifice, 107...Liquid droplet, 108...・・・・・・
・Board, 109...Power supply, 110...
Recorded member, 111...Groove plate, 201...
...recording head, 202...discharge orifice,
203... Orifice side end, 204...
... Energy acting part, 205 ... Inlet side end, 206 ... Electricity/thermal converter, 207 ...
...Liquid storage tank, 208... Conduit, 209.
...Liquid, 210...Inflow port, 211.
...Bubble, 212...Droplet, 213...
····Recording paper.

Claims (1)

[Claims] 1. It has an orifice side end portion with a discharge orifice at the tip, a thermal energy acting part, and an inlet side end part having an inlet communicating with the energy acting part and supplying liquid to the part. In a liquid jet recording method in which a recording head is used and thermal energy is used to fly the liquid ejected from the ejection orifice as droplets and make the droplets adhere to the recording surface for recording, the area of the ejection orifice is S. , when the length of the orifice side end is L_1, the distance between the orifice and the recording surface is √S or more and 50L_1
A liquid jet recording method characterized by recording while maintaining the following: