JPS63191649A - Ink jet head - Google Patents

Abstract

PURPOSE:To enable utilization of flow path design and manufacturing process of a drop on demand type head and to enable production of print dot having micro diameter even with low voltage, by providing an ink flow path of suck structure as the ink liquid level displaces according to a drive signal, then delivering an ink drip through air flow and making a record onto a paper. CONSTITUTION:Direction of air flow and ink drip flow is shown by an arrow B. Ink flow paths 9, 10, 11, 12 are coupled to an air flow path 8, so as to supply ink through an ink flow-in hole 14 made through an ink sump 13 to respective flows. Diameter of dot can be varied by a factor of at most four by driving selected number of four ink flow paths. When flow paths 9, 10, 11, 12 are designed to have different diameters, more gradations can be obtained through combination of driving nozzles.

Description

[Detailed description of the invention] 3. 6°PMIJ description of the invention [17i! INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a print head for an ink jet serial dot printer.

[Prior Art] Various types of inkjet print heads have been devised for conventional serial printers. Among these, the drop-on-demand method requires a high driving voltage when designing a flow path when trying to obtain a dot with a minute diameter.
There were problems such as poor excretion of air bubbles in the flow path. Furthermore, in the so-called valve jet force type in which a heating resistor element is embedded in a nozzle and ink is ejected by the pressure of bubbles generated by the heat generated by the nozzle, the dots are irregularly shaped and there is a problem in print quality. Solid ink is melted by arc discharge,
The method of obtaining ink droplets has problems such as the need for a high voltage as a driving voltage.

In addition, with conventional inkjet heads, there are only a limited number of methods that can change the ink dot diameter, and the draw-on-demand type, which has a simple structure, is only able to change the diameter of the ink dots.
However, l”−/l−W cannot be changed,
This was disadvantageous when printing images with gradation.

Furthermore, when performing color printing, conventional methods fill multiple nozzles or multiple heads with color ink, and control the printing position to perform overlapping printing, which mixes the colors of the inks.

It was multicolored. This method causes differences in the absorption time of ink to paper, so depending on the order of mixing colors,
Differences appear in color development. For this reason, in color serial printers in which different color printing and nozzles are arranged horizontally with respect to the head carriage, the order of colors printed on the paper is different between right-hand printing and left-hand printing, resulting in color mixing. Printing had the disadvantage that the colors appeared dull.

Common disadvantages of conventional inkjet methods include the ink droplet: - When the diameter of the ink is large, there is a problem with the quick drying of the ink, and if the ink takes a long time to dry, the printed characters may stick to other paper or Problems such as printing smudged occurred. For this reason, it was necessary to use highly permeable ink itself or to use special paper.

[Problems to be Solved by the Invention] The purpose of the present invention is to make it possible to apply the flow path design and manufacturing process of 7D to drop-on-demand bottles, and also to produce printed dots with a minute diameter even when driven by low voltage. do. Another purpose is to change the diameter of an ink droplet by several times depending on the drive signal. Furthermore, it is an object of the present invention to be able to obtain the same color regardless of the printing force direction even in color printing by mixing colors.

[Means for Solving the Problems] The ink shared head according to the present invention is characterized in that a structure consisting of one air flow path and -wood or a plurality of ink flow paths is used as one printing nozzle. do. In addition, when in the printing state, a steady air flow is generated in the air flow path,
The ink flow path intersects the air flow path at a certain angle,
At the intersection, the open 1.1 end of the ink flow path may be connected to the empty/A flow path.

Furthermore, an ink chamber is created on the ink flow path side, and one or both wall surfaces of the ink chamber portion are driven by an off-board surface such as a piezo diaphragm. It is preferable to have a structure that causes a height displacement of the ink liquid level at the opening end of the channel.

[Function] An ink chamber is provided in a part of the ink flow path, and a piezo diaphragm is installed on the wall of this single-edged or double-edged blade. When pulse waveform electricity No. 48 is applied to this piezo plate, the piezo crystal that responds to the waveform is activated. You can get change. In other words, when a voltage is applied, the piezo plate bends, and when the voltage is lower or no voltage is applied, the piezo plate does not deform.Using this fact, the drive 't' The volume change of the ink chamber can be obtained through the ink flow path.
This causes a displacement of the ink liquid level at the edge. If the driving voltage and pulse width are appropriate, the ink can be sprayed with the same principle as the conventional drop-on-demand inkjet head. A low voltage is enough to reduce the displacement.
Also, the pulse width may be short.

In this method, a steady air flow is generated in the air flow path that intersects with the open end of the ink flow path, and 1.
By creating a negative pressure at one end, it is easier for the ink droplets to separate from the liquid surface, and at the same time, the ink droplets that have left the liquid surface are carried within the air flow path by the air flow and are further blown onto the paper surface. . In other words, the energy of the piezo-driven pressure is reduced, and the energy that generates the air flow compensates for the deficiency and causes the ink droplets to fly.

In addition, by creating a configuration with multiple ink flow channels connected to the air flow channel, it is possible to control how many ink flow channels the drive signal is applied to, and adjust the number of ejected ink droplets to the ink flow. ITJ can be changed up to 6 numbers.From this, the size of the print dot diameter on the paper can be controlled.
Similarly, up to the number of ink channels can be used with one nozzle.

You can get multiple colors.

[Example] Fig. 1 shows an example of the inkjet head of the present invention.
Figure 1 shows a perspective view of two trunks, where 1 is a channel substrate made by injection molding of polysulfone. 6 is the ink flow path, depth 40
The channel width is 30 to 70 m. 7 is an ink chamber, which has a depth of about 60 JLm. Reference numeral 5 denotes an air flow path, which has a width of 4 mm and a height of 2 mm at the end of the paper surface r''. 2 is a polysulfone plate, which is adhered to the channel substrate 1. Furthermore, the electrode plate 3 and piezo plate 4 are bonded together. Here, the piezo plate 4 has a gold thin film formed by Au sputtering on the opposite side of the adhesive surface to the electrode plate. A line 43 for piezo drive is taken out from this gold thin film and the electrode plate 3.The air flow path is connected to the air flow generation fan part by a polyethylene tube, and the flow path from the ink chamber is as follows. Connect to the ink tank with a polyethylene tube. In the head with this configuration, when an air flow is sent in the direction of arrow A and the piezo plate 4 is driven, ink droplets are generated in the direction of arrow A. Here, the ink had a viscosity of about 2 to 4 mPa-s. The 177 drops obtained at this time were about 0.3 to lug.

FIG. 2 is a flow path diagram of another embodiment. The direction of flow of the air flow and the ink flow here is indicated by arrow B. In this example, for the air flow path 8, the ink flow paths 9, 10.1
1.12 are connected, and ink is supplied to each channel from the ink flow hole 14 in the ink reservoir 13. In this example.

Depending on how many of the four ink channels are driven, the driver I/diameter can be changed up to four times as much.

9.10.11.12 - If all the ink flow path diameters are set to be different, it is possible to obtain even more gradations by combining the nozzles to be driven.

FIG. 3 is a flow path diagram of another embodiment. Here, the arrow C indicates the flow direction of the air flow and the ink droplets. The ink flow opening to the air flow path 15) 516 is for yellow ink, and the same <17 is the flow path for magenta ink.
18 is a flow path for cyan ink, and 9 is a flow path for black ink.

This method uses a combination of driven ink channels to
Color printing can be obtained.

Figure ff14 is a perspective view of an embodiment in which multi-dots are formed. The arrows indicate the flow directions of airflow and ink droplets, and seven layers of flow channels are stacked from the top to the bottom in the figure. Here, 20 is a channel base in the uppermost layer, and 23 is an ink channel. On top of this, a polysulfone plate, an electrode plate, and a piezo plate are glued together, and a plastic plate covering the entire upper surface is adhered to close the upper surface of the air flow path 24. 21 is rrS2! It is a polysulfone board,
22 is a fixing substrate. In this example, 4 per layer.
The printing nozzle formed from the ink flow path of the book is 7 vertically
Since it is made up of layers, up to 7 dots can be printed simultaneously. It is also possible to stack even more layers. Any dot can produce a change in dot diameter size of up to four times. In this embodiment, a fan is attached to the rear of the head to obtain airflow in the direction of the arrow.

FIG. 5 is a perspective view of an embodiment in which multi-nozzle design is implemented with six nozzles. The dot flight direction and airflow direction are indicated by arrow E. 28 is an upper surface fixing plate, and 27 is a lower surface fixing plate, which creates an air flow path. 25.
26 is exactly the same as a conventional drop-on-demand type inkjet head having three nozzles each. However, the driving voltage may be approximately 1/2, and the nozzle tip is open toward the inner air flow path.

As is clear from the embodiments shown in Figures 1, 2, and 3, the positional relationship between the ink flow path and the air flow path may be reversed in any of the examples. Even in the configuration where the channel is on the lower side, ink droplets do not drip due to the surface tension of the ink itself.

In the embodiments shown in Figures 4 and 5, it is possible to not only install a fan on the back side of the air flow path, but also install a nichrome wire heater on the entire surface of the fan to send hot air. 6 is a perspective view of one such embodiment, and 29 is the head portion of FIG.

[Effects of the Invention] The inkjet head of the present invention can be made into a multi-nozzle structure very easily by, for example, arranging the basic configuration shown in the m1 diagram in the horizontal direction. In addition, since the energy for producing the dots is mainly obtained from the air flow, the drive voltage of the piezo plate may be low, which simplifies the design of the power supply and drive circuit. In this case, the resulting dots are also smaller than in the drop-on-demand type, making it suitable for high-density printing. Furthermore, as is clear from the example in FIG. 3, even when printing in color, there is no difference in color when mixing colors depending on the printing direction.
For example, as shown in the embodiment in FIG. 2, it is possible to print with gradation, and the dot diameter can be varied several times. Further, in an embodiment in which a heater is attached to the front of the fan that generates the air flow, the drying time of the ink is shortened, and printing on plain paper can be effected without smearing.

[Brief explanation of the drawing]

Figure t51 is a perspective view of one embodiment of the present invention, 1 is a flow path substrate, 2 is a polysulfone plate, 3 is an electrode plate, 4 is a piezo plate,
5 is an air flow path, 6 is an ink flow path, and 7 is an ink chamber. FIG. 2 is a flow path diagram of another embodiment, 8 is an air flow path, 9 to 12
13 is an ink flow path, 13 is an ink reservoir, and 14 is an ink inflow hole. FIG. 3 is a flow path diagram of another embodiment, and 15 is an air flow path 16 to 1.
9 ink flow paths. FIG. 4 is a perspective view of one embodiment of the inkjet head of the present invention, which is designed to have multiple dots. Figure fjSs is a perspective view of another embodiment of the inkjet head of the present invention, which is designed to have multiple dots. FIG. 6 is a perspective view of an embodiment with a heater, and 31 is a Nichrono wire heater. Above Part 1 “1 Day 2”

Claims (1)

[Claims] An inkjet head characterized by having an air flow path and an ink flow path structured to cause displacement of the ink liquid level in response to a drive signal, and ejecting ink droplets using the air flow to record on a paper surface or the like.