JPH02178054A - Recording device - Google Patents

Abstract

PURPOSE:To decrease the variation width of the diameter of pixels under constant recording conditions and modulate the diameter of dots to realize easy density gradation recording and further line print recording by applying voltage to a signal electrode in accordance with an image signal to increase the viscosity of ink from an ejection aperture and discontinuing application of the voltage to allow an attracting electrode to attract ink to be sent flying to an object to be recorded on in liquid droplets for printing. CONSTITUTION:An ink head 1 has a discharge aperture 2 at the tip and contains ink 3 which becomes solid or viscous significantly by an electric field inside. Then if an image signal which is output from a computer during image formation, switches 13, 14 are turned OFF to cancel or reduce voltage applied to signal electrodes 6, 6' from a DC power supply 11. Consequently, the viscosity of ink in the discharge aperture 2 addresses. In the meantime, a specified voltage is constantly applied to an attracting electrode 9 from a DC power supply 12, and ink 3 is attracted by this voltage and sent flying from the discharge aperture 2 to form an image on recording paper 8. Consequently, the flow of ink is stopped by application of a low voltage to the signal electrode and an image of constant size is obtained without 'image tailing'. In addition, no significant misalignment of a dot position occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a recording device that visualizes an image signal output from a computer, a word processor, etc. on recording paper, and in particular, to a recording device that uses ink whose viscosity changes depending on an electric field to create an image. The present invention relates to a recording device that forms an image on recording paper by controlling the flow of ink by controlling an electric field applied to ink according to a signal.

Conventional Technology A print head has an ink ejection port that ejects ink whose viscosity changes due to an electric field, a signal electrode provided near the ejection port, and an application means that applies a voltage to the signal electrode in accordance with an image signal. A recording apparatus having the above-mentioned type is already known, for example, as seen in Japanese Patent Publication No. 11315/1983.

However, in such a recording device, the ink ejection speed is relatively slow, making high-speed recording impossible, and even if you try to change the dot diameter to perform gradation recording, the variation is large, so gradation recording is difficult. This is impossible, and there is a problem in that even if you try to record in binary, you will not be able to obtain a sharp image.

Problems to be Solved by the Invention Therefore, as a recording device that solves these problems, a vibration is applied at a level that causes the ink in the print head to be ejected as droplets, and the timing for turning off the voltage applied to the signal electrode is determined. A method has been proposed in which the timing at which the pressure at the ink ejection port increases due to this vibration is synchronized.

However, in this type of recording device, although it is possible to change the dot diameter stably, the ink is ejected as droplets and always subjected to a constant vibration, so it is necessary to maintain the minimum size of the ink for the ink to be ejected. Since the ink droplets must be formed into droplets, there is a problem in that it is difficult to perform gradation recording by changing the size of the ink droplets.

Another type of recording apparatus has been proposed that solves the problems of the above-mentioned known recording apparatus, and this type is one in which pressure is applied to the ink in the print head to eject it as ink droplets.

However, in such a recording device, it is necessary to apply an electric field to solidify the ink and stop its flow, so a relatively high electric field is applied to the ink, which requires an expensive driver to control a high voltage. A circuit is required. Also, before turning off the device, it is necessary to release the applied pressure by some means, because when the voltage applied to the signal electrode is removed, the remaining pressure due to the fluidity of the ink will cause the ink to become inactive. This is because the necessary discharge occurs, and if such a pressure relief device is provided, the problem arises that the overall structure of the device becomes complicated and expensive.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problems of the conventionally known or proposed recording devices as described above, to reduce the voltage applied to the signal electrode according to the image signal, and to reduce the voltage applied to the signal electrode according to the image signal under certain recording conditions. It is an object of the present invention to provide a recording device which can easily perform gradation recording by reducing the fluctuation width of the pixel diameter and modulate the dot diameter, and which can use an inexpensive head capable of line print recording.

Means for Solving the Problems In order to achieve the above objects, the present invention provides an ink supply means for supplying ink whose viscosity changes due to an electric field to a print head, an ink discharge port provided in the print head, A pair of signal electrodes are provided facing each other near the ink ejection port, an applying means for applying a voltage to the signal electrodes in accordance with an image signal, an ink suction electrode provided in front of the ink ejection port, and an ink suction electrode provided in front of the ink ejection port. means for supplying a recording medium between the ink suction electrode and the ejection port;

The apparatus includes an applying means for applying a voltage between the signal electrode and the ink suction electrode.

Function: In the recording device of the present invention as described above, when a voltage is applied to the signal electrode according to an image signal, the ink at the ejection port becomes viscous, and when this application is removed, the suction to which the voltage is applied increases. Due to the suction force of the electrodes, the ink becomes droplets and flies toward the recording medium to perform printing.

Embodiment In FIG. 1, reference numeral 1 designates a print head having an ejection port 2 at its tip and retaining ink 3 that solidifies or increases in viscosity due to an electric field. An ink container 5 containing an ink bag 4 is detachably installed, and the discharge port 2 is provided with signal electrodes 6, 6' facing each other. Incidentally, a prescription example of the ink 3 will be described later.

Reference numeral 8 indicates a recording member that is conveyed in a right angle direction by a conveying means (not shown) in front of the ejection port 2, and a suction electrode 9 for ink and suction is arranged on the opposite side of the recording member 8 from the ejection port 2. It is.

This suction electrode 9 is held by a holding member 10.

Reference numeral 11 indicates a DC power supply that applies voltage to the signal electrodes 6 and 6', 12 indicates a DC power supply that applies voltage to the attraction electrode 9, and 13 and 14 indicate switches provided in the voltage application circuit, respectively.

In the above printer, the print head 1 is coated with gold, platinum, nickel, copper, etc. by vacuum deposition, etching, printing, etc. on a base material made of an insulating material such as ceramics such as alumina and silica, glass, and plastics. It may be provided with signal electrodes 6, 6' consisting of the like, and thus it is possible to easily form not only one having a single ejection port 2 but also one having a plurality of ejection ports.

In order to provide a plurality of ejection ports in this way, it is also possible to form partition walls between the ejection ports using photosensitive resin, but when using ink that solidifies by an electric field, the partition walls can be formed using a partition wall forming electrode. It is possible to manufacture the product at a low cost.

Furthermore, in addition to this, as shown in FIG.
, 7' can be provided with a plurality of pairs of signal electrodes 6, 6' in the slit-shaped ejection opening 2 formed by the slits 2, and the print head 1 can be manufactured more easily.

When the print head 1 is provided with a plurality of ejection ports 2 or a plurality of pairs of signal electrodes 6, 6' as described above, a suction electrode 9 is provided correspondingly to each ejection port. It is preferable to use a single electrode common to each pair of signal electrodes, since this is inexpensive.

The ink bag 4 is mainly made of a polymeric material such as polyethylene, polypropylene, vinylidene chloride, rubber, or the like.

The back electrode 9 is made of a thin wire made of stainless steel, tungsten, gold, nickel, etc., and the holding member 10 is made of an insulating material such as polyvinyl chloride, polyamide, polyacetal, phenol resin, etc.

Next, an example of the formulation of the ink used in the above will be shown.

150 parts by weight of cellulose powder was mixed with 60 parts by weight of carbon disulfide, left at 25°C for 5 hours, then dissolved in 1400 parts by weight of a 7% by weight aqueous sodium hydroxide solution, and further mixed with 200 parts by weight of polyethylene glycol. was added and dissolved. This solution is sprayed in a mist form at a pressure of 60 atm from a nozzle with a diameter of about 5 μm to form droplets, and the droplets are introduced into a bath consisting of a 4% by weight sulfuric acid aqueous solution to obtain regenerated cellulose spherical particles. Ta. The obtained particles were filtered and fractionated using a centrifugal filter, then suspended in a large amount of water, and filtered and fractionated again.

After 4 parts by weight of the obtained particles were added to 200 parts by weight of a 2% by weight aqueous solution of Reactive Blue 14, 5 parts by weight of sodium hydroxide was added and stirred for 3 hours to dye the particles. The particles were filtered and fractionated using a centrifugal filter, washed with a large amount of water in the same manner as above, and then dried in a vacuum dryer. After drying, particles having a particle size of 7 μm or more were removed using a cyclone classifier.

1.1' of 25 parts by weight of colored particles excluding coarse particles
- mixed with 75 parts by weight of bis(bromophenyl)methane;
A test ink composition was obtained by performing a dispersion operation for 10 hours in a ball mill.

In the above-mentioned recording apparatus, when an image is not formed, the switch 13.14 is turned on and a predetermined voltage is applied from the DC power supply 11 between the signal electrodes 6.6', and the voltage near the ejection port 2 of the print head 1 is The ink will not solidify or increase its viscosity and will not be ejected from the ejection port 2.

Next, when forming an image, when an image signal output from a computer, word processor, etc. is input, the switches 13 and 14 are turned off and the voltage applied to the signal electrodes 6 and 6' from the DC power supply 11 is released. or lower than the specified voltage.

This reduces the viscosity of the ink in the ejection port 2. On the other hand, a predetermined voltage is constantly applied to the suction electrode 9 from a DC power supply 12, and this applied voltage attracts the ink 3 in the ejection port 2, causes the ink to fly from the ejection port 2, and forms an image on the recording paper 8. It will be formed. As an example of use, signal electrodes 6 and 6' are set to +80V and -gov, respectively.
is applied by a power source 11, and a power source 12 is applied to the attraction electrode 9.
When a DC voltage of -2.7 KV was constantly applied, the suction electrode 9 was placed 0.6 mm from the ejection port 2, and image recording was performed at a maximum recording frequency of 200 Hz, a clear image was obtained.

The signal electrodes 6, 6' are 3360 pieces (8 dots/purchase) in the case of an A-4 version with a width of 210 mm, and the print head 1 is usually fixed during printing, but in high-speed printing When you don't have it and need it.

The print head 1 may be arranged parallel or obliquely to the conveyance direction of the recording member 8, and may be installed so as to scan in a direction perpendicular to the conveyance direction.

Although not shown, the terminals on the electrodes 6 and 6' are connected to ground, for example, so that the electrodes 6 and 6' have the same potential and a constant potential when the switch 13.14 is turned off.
Connect the switch.

In such a recording device, gradation recording is possible by modulating the off time of the switches 13 and 14, the voltage of the power source 11, or the application time or voltage of the electricity 11i12, respectively. Record stably,
Moreover, if the device is to be made inexpensive, it is sufficient to provide a control device that adjusts the voltage application time to the signal electrodes 6, 6' in accordance with the gradation signal of the image.

Normally, the ink suction force caused by the electric field acts strongly when the ink meniscus is convex as shown in Figure 3 (A), and the ink flies well. Since there is no need to apply high pressure to create a convex meniscus, the ink flow can be controlled by applying a low voltage to the signal electrode, compared to a recording device that applies high pressure to the ink to eject the ink. can be stopped.

In this invention, the ink is attracted by the electric field and flies at a relatively high speed.
Unlike the one described in Publication No. 5, there is no trailing of the image, it is possible to move around an image of a constant size, and the position of the dot does not shift significantly.

Furthermore, in a recording device that applies pressure to ink to eject it, even if the ink connection between the pressure application means and the print head is cut off by a valve, the pressure due to expansion of the head member due to pressure, contraction of ink, etc. Since the ink remains in the print head, unnecessary ink is ejected from the ejection ports when the power of the entire recording device is turned off and the voltage between the signal electrodes is released. Since no pressure or only very small pressure is applied to the ink, the ink is not ejected from the ejection port due to its surface tension as shown in FIG. 3(B).

In addition, although FIG. 1 shows a case in which the same voltage is continuously applied between the electrodes 6, 6' and the suction electrode 9 by the DC power supply 12, in this case, the ink flow is sharply applied. Since it is difficult to stop, the amount of ejected ink varies from dot to dot.To prevent this, the signal electrodes 6, 6'
The disadvantage is that a relatively high voltage must be applied between them.

Therefore, in order to prevent this, if a pulsed voltage is applied to the suction electrode 9, the force to periodically suck the ink is lost, so a relatively low voltage is applied between the signal electrodes 6 and 6' to harden the ink. It can be solidified, but in this case, of course, this pulse or the peak of the alternating voltage must be synchronized with the voltage application (voltage release) between the signal electrodes 6, 6', so in this case, The frequency of the pulses should be equal to the maximum of the pulses or alternating current between the signal electrodes 6, 6', or an integral multiple thereof.

Effects of the Invention The present invention is as described above, in which ink whose viscosity changes depending on an electric field is supplied to a print head having an ink ejection port by an ink supply means, and a signal electrode is provided near the ink ejection port, and a recording member is provided with a signal electrode near the ink ejection port. A suction electrode is provided on the opposite side of the signal electrode from the signal electrode, and means for applying voltage to these electrodes is provided, and the suction electrode suctions ink from the ink ejection port. Compared to other devices, an ink pressurizing device is not required, making the entire device more compact and inexpensive.Also, thanks to the surface tension of the ink, even if the voltage applied to the signal electrode is low, the ink does not leave the ejection port. There is no unnecessary ejection, and the rapid flight of the ink by the suction electrode prevents image trailing, reducing the range of variation in pixel diameter, and the dot diameter can be modulated by adjusting the voltage or application time. This has the advantage that gradation recording can be easily performed using the method, and the print head can be provided at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view of an embodiment of the present invention, FIG. 2 is a perspective view of the front part of an example of the print head mentioned above, and FIG.
)(B) is an explanatory diagram showing different states of ink at the ejection port. DESCRIPTION OF SYMBOLS 1... Print head, 2... Discharge port, 3... Ink, 5... Ink container, 6.6'... Signal electrode, 8...
...Recorded member, 9... Attraction electrode, 11.12...
Power supply, 13.14... switch.

Claims (1)

[Claims] 1. An ink supply means for supplying ink whose viscosity changes depending on an electric field to a print head, an ink discharge port provided in the print head, and a pair of signal electrodes provided opposite to each other near the ink discharge port. , an applying means for applying a voltage to the signal electrode in accordance with an image signal, an ink suction electrode provided in front of the ink ejection port, and a means for supplying a recording medium between the ink suction electrode and the ejection port; A recording device comprising applying means for applying a voltage between a signal electrode and an ink suction electrode.