JPS6216825B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording head for inkjet recording that is capable of electronic plane scanning.

There are various existing recording methods such as electrostatic recording, thermal recording, discharge breakdown recording, and electrophotography, but all of them except electrophotography use special recording paper and are expensive and expensive. There are problems with the complexity of the recording mechanism, the lifespan of the recording, etc. For this reason, inkjet recording methods that allow direct recording on plain paper have recently attracted attention. This jets ink accelerated by an electric field from a nozzle that is supplied with ink onto the surface of a recording medium that moves relative to the tip of the nozzle while maintaining a constant distance from the tip of the nozzle. It has various advantages such as low cost, no noise, and long recording life.

However, in the inkjet recording system, electronic plane scanning, in which a large number of nozzles are lined up and scanned by electrical switching, has not been put to practical use. The reason for this is that it is technically difficult to arrange a large number of nozzles at a ratio of several nozzles per 1 mm and to provide sufficient insulation to enable control with high voltage, and it is difficult to put it into practical use. For this reason, it is difficult to reduce costs.

FIG. 1 is a schematic diagram illustrating the basic principle of inkjet recording.

In this figure, 1 is an ink container, 2 is ink, 3 is a nozzle, 4 is a drum, and 5 is the drum 4.
6 is a bias power supply, and 7 is an image signal source.

FIG. 1 shows an example in which cylindrical scanning is applied to facsimile recording, and a portion of the ink 2 from the tip of the nozzle 3 connected to the ink container 1 forms a meniscus. In this state, an image signal with a bias of about 2KV is applied to the nozzle 3 and the rotating drum 4.
When the voltage is applied between , the ink 2 is ejected from the nozzle 3 according to the image signal, and an ink image is formed on the recording paper 5. This principle is known.

In order to perform electronic plane scanning using this principle,
An example has been reported in which an inkjet recording head was fabricated in which a large number of nozzles were arranged at a density corresponding to several nozzles per 1 mm. However, this has not reached a practical level for the reasons mentioned above.

The inventors discovered a new fact and found that this problem can be solved. That is, the conventional thinking was that the ink meniscus formed by the tip of the nozzle must be independent for each nozzle. However, we discovered that this is not necessary, and that even in the case of a continuous meniscus, the ink behaves in the same way as an independent ink meniscus depending on how the image signal is applied.
Based on this fact, we previously proposed a recording method that allows electronic plane scanning. This will be explained below.

FIG. 2 is a perspective view showing the previously proposed inkjet recording system.

In this figure, 11 is a slit-shaped ink supply port, 12a and 12b are an upper plate and a lower plate made of an insulating material forming the supply port 11;
13 is a large number of electrodes arranged periodically on the lower plate 12b, 14 is a grounded counter electrode arranged opposite to the supply port 11, and 15 is a grounded counter electrode 14.
16 is a driving power source that supplies a high voltage to selected electrodes of the electrodes 13. When ink is injected into the supply port 11, the supply port 11
A continuous meniscus is formed, and when a high voltage is supplied from the drive power supply 16 to one or more selected electrodes 13, the ink near the selected electrode is ejected from the supply port 11 and onto the recording paper 15. It is attached and recorded. The voltage applied at this time is several hundred μ
It is important to apply the pulse with a short pulse of about s,
When a DC voltage was applied, ink was intermittently ejected from a plurality of positions, and recording corresponding to the selected electrode 13 could not be obtained. By using such short pulses, it was possible to select any electrode to eject ink. The conditions used for this recording are that the electrode arrangement density is 8 electrodes/
mm, the width of the top and bottom of the supply port 11 is 50 μm, the supply port 11
The distance between and the grounded counter electrode 14 is 130 μm, and the applied voltage
The ink was 2 KV, the pulse width was 250 to 350 μs, the ink was for Copics model TA-440 manufactured by Toshiba Corporation, and the hydrostatic pressure of the ink was 5 to 13 mm. in this way,
The vertical width of the supply port 11 is 50 μm, and the horizontal length of a large one is as much as 200 mm, so making the supply port 11 with a vertical width of 50 μm means that the upper plate 12a and the lower plate 12b are quite thick. It was extremely difficult to use anything.

This invention was made in order to solve the above-mentioned problems, and is an inkjet recording device in which a plurality of ink supply ports are provided, and the partition wall forming each supply port is a spacer that determines the height of the supply port. It provides a head. This invention will be explained below.

FIGS. 3 and 4 are perspective views showing an embodiment of the present invention, mainly showing the supply port.

In this embodiment, the ink supply port 11 is connected to the electrode 1
3 as partition walls, and the electrode 13 also serves as a spacer, and its thickness regulates the vertical width of the ink supply port 11 to the ideal width of the ink supply port. . However, as shown in FIG. 4, when the ink 2 is injected into the supply port 11, the electrode 13 gets wet with the ink 2, so the divided supply port 11 is hidden and the ink 2 is injected into the continuous meniscus 2.
Form A. Even in this state, the ink 2 was ejected from the position corresponding to the selected electrode 13, and the ink 2 could be ejected from any position by electronic switching. At this time, the upper plate 12a
By bringing either or both of the lower plate 12b and the lower plate 12b forward compared to the electrode 13, it was possible to increase the maximum response speed of ink jetting. Note that 17 is a side plate.

Next, the formation of the meniscus in the above will be explained.

By applying an appropriate pressure to the ink 2, the ink 2 does not flow out from the supply port 11, and a linear meniscus can be formed. In this case, the width of the partition wall (electrode 13) must be small;
As shown in the example, the width of the partition wall is equal to the width of the electrode 13.
This is determined by the density of pixels to be recorded. Generally, the pixel density is 8 pixels/
mm or more, and the width of the electrode 13 is 1 mm/8 pixels, that is, 125 μm or less. It has been confirmed that if the partition wall width is on this level, a linear menicus will be formed as long as common materials are used.

5 to 7 are front views showing the relationship between the supply port and the electrodes in other embodiments of the present invention.

FIG. 5 is basically the same as FIG. 3, but the metal foil on the lower plate 12b is photo-etched to form the electrode 1.
The resist 18 used when forming the photoresist 3 is still used. That is, the electrode 13 and the resist 1
8 is formed into a spacer, and its thickness is made the same as the thickness of the spacer 19 made of other members. There are two types of resist 18: one with resist attached to the cut end of the front end, and one without it. In the case of resist attached to the cut end of the front end, when one electrode 13 is selected, the resist is removed from the left and right sides of that electrode 13. Two pieces of ink squirted out. This could be achieved by applying a voltage to the selected electrode 13 and at the same time applying a voltage to one of the adjacent electrodes so that no ink would be ejected from that electrode.

In FIG. 6, electrodes 13 and resists 18 are provided in this order on the upper plate 12a and the lower plate 12b, respectively.
The electrodes 13 on the lower plate 2a and the lower plate 12b are arranged alternately.

FIG. 7 shows an example in which a protrusion 13a is provided on a part of the electrode 13 to increase the maximum response speed.

In each of the above embodiments, a continuous linear meniscus was formed at the outlet of the supply port 11, and ink could be ejected from any arbitrary position in this state.

In addition, although the above embodiment describes an example in which the electrode 13 serving as a spacer is provided for one supply port 11, a plurality of electrodes 13 that do not serve as a spacer may be provided for one supply port 11. The electrodes 13 acting as partition walls may be provided at regular intervals.

In this embodiment, a protrusion 13a is integrally formed on the electrode 13 shown in FIG.
The electrode 2b is configured to protrude beyond the line at the tip thereof, and it goes without saying that this configuration can be applied to the electrode 13 of other embodiments.

As explained above, this invention is formed using electrodes in a direction perpendicular to the direction in which the electrodes are arranged in the ink supply port, and is provided with a spacer whose height is the ideal width of the ink supply port. When manufacturing a recording head for inkjet recording in the form of an inkjet recording head, it is possible to make the vertical width constant over the entire length of the left and right sides of the ink supply port, which has the advantage of facilitating manufacturing.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the basic principle of inkjet recording, Fig. 2 is a perspective view of the previously proposed printing method capable of electronic plane scanning, and Figs. 3 and 4 show an embodiment of the present invention. The perspective views before and after ink supply, FIGS. 5, 6, and 7 are front views and perspective views showing other embodiments of the present invention. In the figure, 2A is a meniscus, 11 is a supply port, and 12
a is an upper plate, 12b is a lower plate, 13 is an electrode, 14 is a grounded counter electrode, 15 is a recording paper, 16 is a driving power source, 1
7 is a side plate, 18 is a resist, and 19 and 20 are spacers.

Claims (1)

[Claims] 1 It has a slit-shaped ink supply port in which a plurality of electrodes are arranged at a distance, and when a high voltage is applied between the electrode and the counter electrode, the ink supplied from the supply port in contact with the electrode is In a recording head of an inkjet recording device that utilizes drawing out in the direction of the counter electrode, the electrodes are formed in a direction perpendicular to the arrangement direction of the electrodes in the ink supply port, and the height thereof is determined by the ink supply port. A recording head for inkjet recording characterized by being equipped with a spacer having a mouth width.