JPS6259673B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses magnetic force to raise magnetic ink on a magnetic multi-stylus facing a recording surface, and causes the magnetic ink to fly or migrate toward the recording surface from the raised portion in response to an image signal. This invention relates to an image recording device.

This type of recording device (i) can produce images with good resolution and contrast; (ii) Basically, no repairs other than ink and toner replenishment are required. (iii) High-speed, high-density recording is possible using multiple styluses.
(iv) Magnetic ink can be self-supplied by magnetic force and does not necessarily require a movable mechanical part for ink replenishment. (v) It has excellent features such as no fixing process and immediate drying after recording.

The present invention particularly relates to a multi-stylus head in this image recording apparatus, which improves the bulge shape of the magnetic ink caused by the magnetic force, facilitates the flight and migration of the magnetic ink in this recording method, and significantly improves the image contrast. Furthermore, it also facilitates the supply of ink to the head, making it possible to perform high-speed and high-density recording using a high-density multi-stylus head.

To be more specific, the image quality and recording conditions according to this recording method depend very much on the shape of the ridges of the fluid toner, and the shape of the ridges with larger undulations (that is, the shape with higher S/N of the ridges) produces a better image. In this recording method, this raised shape is the most important factor. In other words, by making the raised shape of the fluid toner into a desirable shape with a high S/N ratio, it becomes possible to record clear images under easy recording conditions.

Therefore, the present invention relates to the formation of a protective film for the head member in this recording method, and includes (a) improving the adhesive strength of the magnetic stylus, (b) preventing magnetic ink from seeping into the gap between the magnet and the stylus, and (c) It has many effects such as improving the dielectric strength between the styli, (d) preventing magnetic sedimentation of magnetic ink, and (e) improving the agent resistance (ink resistance) and elasticity of the bump magnet made of rubber magnet. It is something that you have.

The head of this type of image recording apparatus is composed of a magnetic multi-stylus, a protrusion magnet, and an ink supply path connected thereto. The magnetic ink supplied to this head is generally called a magnetic fluid, and is a liquid in which fine particles of magnetite (Fe ₃ O ₄ ) (approximately 100 Å in diameter) are suspended in a dispersion medium together with a surfactant. It is a liquid that is stable for a long time and does not cause sedimentation or agglomeration. Dispersion media for this magnetic fluid include paraffin, water, ester oil, silicone oil, etc., and surfactants include carboxylic acids such as oleic acid and linoleic acid, as well as cationic activators, nonionic activators, etc. be done. Magnetic fluids are said to exhibit superparamagnetism,
It is a magnetic material with no magnetic hysteresis. In the present invention, paraffin-based magnetic fluid is mainly used.

In this type of image recording device, methods for making a fluid fly or migrate in response to an image signal include (A) converting the image signal into voltage and applying Coulomb force, and (B) converting the image signal into an electromagnet. There are methods such as applying an additional magnetic force, (C) a method that combines the above (A) and (B), and the present invention can be used with any of the above methods (A), (B), and (C).

Next, the structure of the multi-stylus head used in one embodiment of the present invention will be described in detail, and the protective film will be explained in detail.

The multi-stylus material is a magnetic material having higher magnetization than magnetic ink, and can be a lead frame or wire made by etching or cutting a thin plate into strips. In addition, the structure of the stylus can be composed of a core material and a covering material, in which case (a) a method using a magnetic material for the core material, (b) a method using a magnetic material for the covering material, (c) a method using a magnetic material for the covering material; ) said above
There is a method of combining (a) and (b). When flying or migrating the fluid toner using Coulomb force corresponding to an image signal, the stylus needs to have both electrical conductivity and ferromagnetism. In this case, (a)
In this case, a conductive wire made of iron, stainless steel, permalloy, etc. coated with a polymer material is suitable, and in (b), a general-purpose conductive wire made of copper, aluminum, etc. mixed with various magnetic powders such as ferrite, magnetite, iron powder, etc. is suitable. Those coated with a resin composition are preferable. This (b)
In this case, the conductive core material is less likely to be exposed from the tip of the stylus where the magnetic ink is raised, so there is less discharge during recording.

Most of the magnetic materials used in such styli are soft magnetic, and do not act as strong magnets by themselves. Therefore, by combining this stylus with a magnet, it can be magnetized and an excellent stylus head can be constructed. On the other hand, hard magnetic metal materials have poor workability, and there are almost no materials that can be made into a thin stylus shape. The present inventors have already proposed a magnetic circuit for attaching a magnet to the above-mentioned soft magnetic stylus and magnetizing it to raise the magnetic fluid toner in Japanese Patent Application No. 137125/1982. In the specification of the above patent application, one of the multi-stylus heads
One structure is shown in FIG. 1, in which a stylus 1 made of a polyurethane-coated wire is combined with a magnet 2. This head is connected to an ink supply path 3 made up of a magnet, and its magnetic force pulls up the magnetic ink 4 in the direction of the arrow in the figure.

The magnet used in the present invention is preferably a magnet with good workability such as a plastic magnet or a rubber magnet. Furthermore, these rubber or plastic magnet materials can be easily molded into minute rod-shaped moldings and used in the present invention, and commercially available anisotropic magnet sheets can be cut and processed to easily form the magnet shape of the present invention. can do. For example, a rubber magnet sheet with a thickness of 1 to 2 mm is magnetized in the NS direction in a direction perpendicular to its surface, and the required magnet can be easily obtained by cutting one side of the sheet diagonally. Further, as the angle of the acute-angled surface relative to one magnetic pole surface of the magnet increases from 0 to 90 degrees, the magnetic force becomes stronger and the force that raises the toner increases. If the angle is less than 30 degrees, the magnetic force will be weak and the magnetization of the stylus tip will not be strong enough, and at the same time, the smaller the angle, the less dimensional accuracy will be achieved by cutting.

The head shown in FIG. 1 is connected to an ink tank 6 as shown in FIG. 2, and an image is recorded by an electrical configuration as shown in FIG. That is, a bias voltage 8 is applied between the stylus 1 of the head and the counter electrode 7, and a scanning pulse voltage 9 (400V) is further applied to the stylus 1 wired in a matrix. Then, the image signal 10 is applied to the counter electrode 7.
When (700V) is applied, the magnetic ink 4 flies from the tip of the head, forming a clear image on the recording medium 11.

In such a wiring recording apparatus, the present invention is characterized in that a protective film 12 is provided on the head member and the tip of the head, as shown in FIG. The protective coating on the stylus is applied for the purposes (a) and (c) mentioned above. When the stylus is made of metal, it is necessary to use a material with good adhesion to the metal for the protective layer, and a material with strong film strength is suitable. As a result, thermoplastic polyester (for example, Toyobo Co., Ltd. Byron RV200), butyral, polyurethane, epoxy resin, etc. had good adhesion, and polyvinyl chloride had excellent mechanical strength. All of these are dissolved in a low boiling point solvent, and a protective film can be easily formed by immersing the head in the solution.
Specifically, it was appropriate to sequentially form a polyester (Vylon) coating and a polyvinyl chloride coating on the stylus. On the other hand, the protective film on the magnet is provided for the purposes (d) and (e) mentioned above. Since the magnetic ink has a strong attraction force in areas where lines of magnetic force are concentrated, some of the magnetically dispersed particles tend to precipitate at the ends of the magnet.
Therefore, by forming this protective film on the magnet surface, the surface magnetic force of the magnet can be reduced and this sedimentation can be prevented. Furthermore, when a resin magnet such as a rubber magnet is used as a magnet, its ink resistance becomes a problem, and even if it is not affected by the ink, the magnet may seep between the magnet particles and the binding material (rubber, resin). Rather than a decrease in magnetic force, the mechanical properties of the magnet are severely lost. The protective coating according to the invention greatly improves the ink resistance of this magnet. When using a rubber magnet based on nitrile rubber, polyvinyl chloride has good adhesion, mechanical strength, and film formability, and forms an excellent protective film.

The head may be constructed after forming protective films on the stylus and magnet, but if the protective film is formed by immersing the head in a polymer solution after bonding the stylus and the magnet, it is possible to form the protective film first. mentioned in
The effect of (a) also occurs, and an excellent head can be formed.
When we recorded images using the head obtained in this way using the method described above, we were able to record clear images, and even when recording continuously for several weeks,
There were no shots between the styli, there was very little sedimentation of the magnetic ink, and the surface of the head was covered with a protective film, making it very easy to clean the head.

As described above, according to the present invention, by forming a protective film on the head member, it is not only mechanically protected but also resistant to chemical changes, and also resistant to changes over time such as deterioration of magnetic ink. It is possible to provide an excellent image recording device that can maintain stable image quality and high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a recording head portion of a conventional image recording apparatus, FIG. 2 is a plan view of this recording head portion, FIG. 3 is a configuration diagram of essential parts showing an embodiment of the present invention, and FIG. 4 FIG. 2 is a side view showing the recording head portion of this embodiment. DESCRIPTION OF SYMBOLS 1... Stylus, 2... Magnet, 3... Ink supply path, 4... Magnetic ink, 11... Recording body, 1
2...Protective film.

Claims (1)

[Claims] 1. A head including a magnetic multi-stylus arranged in a straight line facing a recording surface and a bump magnet provided on the multi-stylus, and magnetic ink supplied to the head. In an image recording device that obtains an image by raising the magnetic ink on the multi-stylus and causing the magnetic ink to fly or migrate on a recording surface in response to an image signal, a protective film continuous to the magnetic multi-stylus and the bumping magnet is formed. An image recording device characterized by: 2. The image recording device according to claim 1, wherein the protective film is made of a polymeric material. 3. The image recording device according to claim 2, wherein the polymeric material is polyvinyl chloride. 4. The image recording device according to claim 2, wherein the magnetic ink is a paraffin-based magnetic ink, and the protective film of the multi-stylus is sequentially formed of thermoplastic polyester and polyvinyl chloride.