JPS6249874B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses magnetic force to raise a magnetic fluid on a magnetic multi-stylus facing a recording surface, and moves the magnetic fluid from the raised portion to a recorded image in response to an image recording signal. This relates to a magnetic fluid recording device that obtains images by flying or electrophoresis, and its purpose is to provide higher density and more stable printing.

Conventionally, in this type of magnetic fluid recording device,
As the linear density of the multi-stylus increases, various problems arise, making it difficult to increase the density of printing. Hereinafter, conventional problems that arise due to an increase in the linear density of a multi-stylus will be explained with reference to the drawings.

FIG. 1 shows the basic configuration of a magnetic fluid recording device. An uplifting magnet 2 is mounted on the magnetic multi-stylus 1 near its tip, and the magnetic multi-stylus 1 is magnetized by the uplifting magnet 2. A magnetic fluid 3 is held on the magnetic multi-stylus 1 and the bump magnet 2, and a magnetic fluid bump 3' as shown in the figure is formed on the magnetized magnetic multi-stylus. The control electrode 4 is placed at a predetermined distance from the magnetic multi-stylus, and the recording paper 5 is placed in contact with the control electrode 4. When a voltage is selectively applied between the magnetic multi-stylus and the control electrode, a Coulomb force acts on the bumps on the stylus to which the voltage is applied, causing the magnetic fluid to fly toward the recording paper 5. Printing is performed sequentially on the top.

Figures 2a and 2c show the shape of the ridges formed on the magnetic multi-stylus. The shape of the ridge is determined by the balance between magnetic force, gravity, and surface tension, and the shape of the ridge has a great effect on the printing condition. The larger the step l of the bump from the tip of the bump to the valley of the bump, the better the selectivity of the flying magnetic fluid from the tip of the bump on the stylus, and the less noise on printing, but the smaller the step l of the bump is. Indeed, the selectivity of the flight from the tip of the protrusion on the stylus deteriorates, and the noise in printing also increases.

This will be explained in more detail. FIG. 3 shows the relationship between the step l of the ridge and the radius r of the tip of the ridge, and the larger the step l of the ridge, the smaller the radius of the tip of the ridge. The smaller the radius of the tip of the ridge, the more likely it is that charge will be concentrated at one point at the tip of the ridge when a voltage is applied, and conversely, the larger the radius of the tip of the ridge, the more likely the charge will be scattered across various parts of the ridge when a voltage is applied. , Difficulty concentrating on one point. FIG. 4 shows a state in which a voltage is applied between one stylus 1 and the control electrode 4. In FIG. In the case of FIG. 4a, the step l of the ridge is sufficiently large, that is, the difference between the distance d between the control electrode 4 and the tip of the ridge and the distance d+l between the control electrode 4 and the valley of the ridge is sufficiently large, so that the ridge is The electric field strength at the tip is sufficiently larger than the electric field strength at the valley of the ridge. Furthermore, since the step l of the ridge is sufficiently large, the radius r of the tip of the ridge is also sufficiently small, so that the charge Q is concentrated at one point at the tip of the ridge, as shown. The flight of a magnetic fluid is caused by a force F determined by the charge Q of the magnetic fluid and the electric field strength E at that location.
＝It happens by receiving EQ,
In the case of Figure 4a, there is a sufficient difference in the electric field strength between the tip of the ridge and the valley of the ridge, and the electric charge Q is concentrated at one point at the tip of the ridge, so the magnetic fluid flies away from the tip of the ridge. It occurs from one point in the part. However, when the step l of the ridge is not sufficiently removed as shown in Figure 4b, the difference between the distance d between the control electrode 4 and the tip of the ridge and the distance d+l between the control electrode 4 and the valley of the ridge. This means that the difference in electric field strength between the tip of the ridge and the valley of the ridge is small, and the radius of the tip of the ridge is large. Scattered. Therefore, not only does the applied voltage necessary for flight increase, but also the flight of the magnetic fluid does not occur from just one point at the tip of the ridge, but from various locations on the ridge, and in extreme cases may even occur from the valley of the ridge. Therefore, if the height difference l between the protrusions is small as shown in FIG. 4b, the printing results in extremely noisy printing.

As explained above, the larger the difference in height between the protrusions is, the better, and it is easier to obtain good printing with less noise. However, when the linear density of the multi-stylus is increased and the stylus pitch is made smaller in order to achieve higher recording density in this type of recording device, the second
As shown in FIG. b, since the distance between the styli becomes small, it is not possible to make the step l of the protrusions sufficiently large, resulting in a problem of extremely increased noise in printing. In addition, a high voltage is applied to the selected point of the multi-stylus, and therefore a high voltage is also applied between the stylus to which high voltage is applied and the stylus to which no high voltage is applied. Increase the linear density of the multi-stylus,
There was also the problem that as the stylus pitch was packed, the withstand voltage between the styli against the applied voltage was lost.

As is clear from the above explanation, there is a limit to increasing the linear density of multi-styli due to the required height difference between the ridges and the pressure resistance between the styli, and the conventional configuration has a stable linear density with little noise. It was difficult to obtain high-quality printing.

In view of these prior art techniques, a configuration of this type of print head that can sufficiently eliminate the step difference in the protrusions and provide higher density printing is considered to be one in which magnetic multi-styli are arranged in two rows in a staggered manner. For a single row of magnetic multi-styli, the stylus pitch is designed to have a sufficient level of protuberance, and two rows of such magnetic multi-styli are arranged in a staggered manner to achieve the linear density of the stylus, that is, the line of printing. The idea is to double the density.
With this configuration, the level difference in the ridges can be sufficiently removed, and the linear density of the multi-stylus can be further increased, making it possible to achieve stable printing with high linear density and less noise. It is. However, if one attempts to construct a head in which two rows of magnetic multi-styli are arranged in a staggered manner, various difficult problems arise. These problems will be explained below with reference to the figures.

FIG. 5 shows an embodiment in which magnetic multi-styli are arranged in two rows in a staggered manner. As shown in the figure, two rows of magnetic multi-styli are arranged in parallel in a staggered manner on both sides of the stylus substrate 6. ing. Each magnetic multi-stylus has two raised magnets.
is installed. Normally, when line printing is performed with a print head having a staggered configuration, a line memory is required in the circuit to delay the timing of printing by the pitch t of the staggered rows. The larger the pitch t, the more line memories are required, and therefore the staggered row pitch t is often required to be very small, t<1 mm. In order to meet this requirement, the thickness of the stylus substrate 6 must also be made very thin. The stylus substrate 6 is preferably made of a non-conductive material in order to maintain insulation between each stylus of the magnetic multi-stylus.
Strong metals cannot be used as materials, and resins such as epoxy and acrylic are usually used. Therefore, it was not possible to maintain sufficient strength of the stylus substrate 6, and it was not possible to guarantee the straightness A of the stylus tip, the flatness B of the array of magnetic multi-styli, etc. in the figure. What has been explained above is a problem in terms of mechanical strength and structure, but there are other major problems in principle with the staggered print head that uses this type of magnetic fluid recording method. be. FIG. 6 shows how lines of magnetic force emerge from the stylus in this type of magnetic fluid recording device and the cross-sectional shape of the ridges of the magnetic fluid formed on the stylus. A bump magnet 2 is attached to the stylus 1, and a bump 3' of magnetic fluid is formed on the stylus 1. As shown in the figure, lines of magnetic force come out from the tip of the stylus 1 toward the side where the bump magnet 2 is located, and therefore the bump 3' is pointed diagonally upward as shown in the figure. It has a shape. FIG. 7 is an enlarged view of part A in FIG. 6, in which a voltage is applied between the stylus 1 and the control electrode 4, and an electrostatic attraction is applied to the tip of the protuberance 3', causing the magnetic fluid to fly. When attempting to do so, the state of its flight differs depending on the positions of the control electrode 4 and the recording paper 5. When a voltage is applied between the stylus 1 and the control electrode 4, the magnetic fluid flies from a point on the protuberance that is closest to the recording paper 5, and the magnetic fluid flies from the starting point onto the recording paper 5. It tries to fly in the vertical direction, that is, the angle δ of the perpendicular line drawn from the tip of the stylus 1 onto the recording paper 5 with respect to the stylus surface (hereinafter referred to as the "angle of the control electrode and recording surface positions"). . Therefore, when the control electrode 4 and the recording paper 5 are at the position I, the magnetic fluid starts flying from the point P _I on the protuberance and flies toward the direction of the angle δ _I. Moreover, when the control electrode 4 and the recording paper 5 are in the position,
The flight of the magnetic fluid starts from point P on the bump,
It flies toward the direction of angle δ. In this way, the flight starting point of the magnetic fluid on the bulge differs depending on the angle δ of the position of the control electrode and the recording paper.

Figure 8a shows the angle δ of the position of the control electrode and the recording paper.
This shows the relationship between the radius r of the tip and the tip radius r at the problem of flying bumps. When δ = δ _n , the radius r of the tip is the smallest, and as δ approaches 0°, and δ becomes 90°.
The tip radius r becomes larger as the angle approaches .degree. As described above, the larger the tip radius of the protuberance, the higher the applied voltage required for the magnetic fluid to fly. Figure 8b shows the angle δ and the applied voltage V required for the flight of the magnetic fluid.
This shows the relationship between As shown in this graph, the required applied voltage V is naturally minimum when δ = δ _n , and the closer δ is to 0° or the closer δ is to 90°, the more the required applied voltage V will rise. Therefore, if two rows of magnetic multi-styli are simply arranged in parallel in a staggered manner, the positional relationship between the magnetic multi-stylus, control electrode, and recording paper can only be configured as shown in FIG. There was a big problem in that the angle δ=0° and the applied voltage necessary for the flight of the magnetic fluid increased extremely.

As explained above, two magnetic multi-styli are used as a means to sufficiently reduce the level difference between the protrusions of the magnetic fluid, to achieve printing with very little noise, and to achieve printing with high linear density and good resolution.
A method of arranging magnetic multi-styli in staggered rows is considered, but in reality, there are many problems with this configuration in which two rows of magnetic multi-styli are arranged in a staggered manner. Moreover, it was not possible to satisfy the demand for printing with high linear density.

The present invention eliminates the above-mentioned drawbacks and will be explained below along with examples thereof. In FIG. 10, the stylus substrate 6 has an acute angle θ at its tip, and two rows of magnetic multi-styli 1 are arranged on both sides forming the acute angle θ in a staggered arrangement at each tip. It is installed. On each magnetic multi-stylus 1, a bumping magnet 2 is attached near the tip of the stylus, and the tip of the stylus has the same magnetic pole between the two rows of magnetic multi-styli. The magnetic poles on the side in contact with the stylus 1 are formed in the same manner. This is to make the shapes of the protuberances formed on the magnetic multi-styli on both sides of the stylus substrate 6 symmetrical on both sides of the stylus substrate. The shape of the ridge formed on the multi-stylus differs on both sides of the stylus substrate, resulting in uneven printing between rows of the magnetic multi-stylus. The stylus substrate 6 has a very narrow width at its tip, but as shown in the figure, the tip has a block shape with an acute angle θ, so it is very strong and magnetic. The straightness of the tip of the multi-stylus and the flatness of the magnetic multi-stylus array can also be sufficiently guaranteed. Control electrode 4 and recording paper 5
And the positional relationship of the two rows of magnetic multi-styli is,
The distance between the tip of the stylus and the recording paper 5 is made to be the same between each magnetic multi-stylus row.
Further, the acute angle θ is set such that the applied voltage required for the flight of the magnetic fluid is the minimum at the angle δ=θ/2 of the position of the control electrode and the recording paper in each column. The angle δ _n of the position of the control electrode and the recording paper at which the applied voltage required for the flight of the magnetic fluid is the minimum varies depending on the magnetic properties of the magnetic multi-stylus and the size and shape of the magnetic force of the bumping magnet. According to experiments, it is in the range of 15° < δ _n < 40°, that is, 30° < θ <
If we set the acute angle θ to satisfy the 80° relationship,
The applied voltage required for the flight of the magnetic fluid can be considerably lowered. Furthermore, the tip of the protrusion magnet used in this example can be made at a right angle as shown in FIG. 11, or at an acute angle as shown in FIG. As shown, when the tip of the bump magnet is used with an acute angle, the flow of the magnetic fluid from the bump magnet 2 to the tip of the stylus 1 improves, the shape of the bump becomes more stable, and the bump It is possible to prevent the magnetic fluid in the C portion attached to the edge portion of the magnet 2 from adhering to the recording surface and causing smearing of the print. Further, as the acute angle of the uplifting magnet increases from 0 to 90°, the magnetic force becomes stronger and the force for uplifting the magnetic fluid becomes stronger. If the acute angle is less than 30°, the magnetization of the stylus tip will not be strong enough, and the acute angle will be less than 60°.
If it exceeds .degree., the magnetic force will be strong, but the flow of the magnetic fluid from the bump magnet to the stylus will be poor, and the recording surface will be more likely to be smudged by the magnetic fluid in the C section. Therefore, the uplift magnet 2
It is desirable to use an acute angle of the tip in the range of 30° to 60°.

As explained above, according to the present invention, since two rows of magnetic multi-styli are arranged in a staggered manner, when the magnetic fluid is raised at the tip of the stylus, the height difference in the raised height is large. In addition, the linear density of the styli can be increased by setting the distance between adjacent styli so that a sufficient withstand voltage can be obtained. In addition, the tip side of each magnetic multi-stylus in two rows is inclined in the direction of the other magnetic multi-stylus, and the angle formed with the tip side as the apex angle is set so that the applied voltage required for the flight of the magnetic fluid is the minimum. Since the configuration is set at an acute angle, the radius of the protruding tip of the magnetic fluid is minimized, and the energy required for the magnetic fluid to fly is minimized. Furthermore, by setting the magnetic poles at the tips of the styli to be the same, the protrusions of the magnetic fluid on the opposing magnetic multi-styli become symmetrical, and the printing on the recording surface becomes even. As a result, it is possible to provide a magnetic fluid recording device that has less noise and can print with high linear density with a minimum applied voltage.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of a conventional magnetic fluid recording device, FIGS. The figure shows the tip radius r of the ridge and the step l of the ridge.
Figures 4a and 4b are schematic diagrams showing the difference in charge concentration due to differences in the shape of the protrusions. Figures 5 and 9 are side views of the device in which the styli are arranged in a staggered manner. Figure 6 is a side view of the same essential part showing the direction of the magnetic field lines and the shape of the ridge, Figure 7 is an enlarged view of the tip of the stylus in Figure 6, and Figures 8a and b are the angle δ and the radius of the tip of the ridge. FIG. 10 is a side view of the main part of a magnetic fluid recording device in one embodiment of the present invention, and FIG. 11 is a side view of the main part in another embodiment. be. DESCRIPTION OF SYMBOLS 1...Magnetic multi-stylus, 2...Elevation magnet, 3...Magnetic fluid, 4...Control electrode, 5...
Recording paper, 6...Stylus board.

Claims (1)

[Scope of Claims] 1. Two rows of magnetic multi-styli in which a plurality of styluses are arranged substantially in parallel, and a magnetic pole located near the tip of each of the two rows of magnetic multi-styli, and a magnetic pole at the tip of each of the styli. a bumping magnet that sets the magnetic fluid to have the same polarity and bumps the magnetic fluid at the tip of the stylus, and a control electrode that is disposed at a position facing the two rows of magnetic multi-styli across the recording surface. , the two rows of magnetic multi-styli are arranged in a staggered manner, and the distal ends of the magnetic multi-styli in each row are inclined toward the other magnetic multi-stylus; In the magnetic fluid recording device, the angle formed by the apex angle is set to an acute angle that minimizes the applied voltage required for the flight of the magnetic fluid. 2. Claim 1, characterized in that the protrusion magnets provided in contact with the vicinity of the tips of each of the two rows of magnetic multi-styli are respectively disposed on the outer surfaces of the two rows of magnetic multi-styli. The magnetic fluid recording device described. 3. The surface on the tip side of the magnetic multi-stylus of the bumping magnet provided in contact with the outer surface of each of the two rows of magnetic multi-styli forms an acute angle with the contact surface of the bumping magnet with the magnetic multi-stylus. A magnetic fluid recording device according to claim 1 or 2, characterized in that: 4. The magnetic fluid recording according to claim 1, wherein the acute angle between the magnetic multi-styli arranged in a staggered manner, with the tip end of the stylus as the apex angle, is in the range of 30° to 80°. Device. 5. The method according to claim 3, wherein the acute angle formed between the surface of the protruding magnet on the tip side of the multi-stylus and the contact surface with the magnetic multi-stylus is in the range of 30° to 60°. Magnetofluid recording device.