JPS6249877B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generates ridges of magnetic fluid at the tips of a plurality of needle electrodes using magnetic force, and flies (moves) the magnetic fluid from the tips of the ridges to the recording surface in accordance with recording signals to record images. This relates to a magnetic fluid recording device that uses an auxiliary electrode to change the shape of the ink ridge at the tip of the recording needle electrode to a shape that allows it to fly more easily than other ridges, thereby improving recording quality. It is.

The conventional inkjet recording method using a nozzle having fine holes has had problems such as the processing of the fine holes is troublesome, the fine holes are easily clogged, and it is difficult to make multilayers. On the other hand, there is a method in which a magnetic needle electrode is magnetized with a magnet, a magnetic fluid is attached to the tip of the needle electrode to form a ridge, and the tip of the ridge is caused to fly onto the recording surface in response to the recording signal, thereby recording. has already been proposed.

This method does not require precision processing techniques or clogging prevention devices such as those of the nozzle type, and it is possible to manufacture a recording device with a simple configuration and low cost.

FIG. 1 shows a schematic configuration of a conventional magnetic fluid recording device using multiple needle electrodes.

In FIG. 1, the needle electrode 2 is magnetized by a magnet 3 and has a magnetic fluid attached to its tip.

The magnet 3 also has a supply function, and uses magnetic force to suck up the magnetic fluid 4 from the tank 5 containing the magnetic fluid 4 and supply it to the tip of the needle electrode 2.

A positive pulse voltage is applied to the needle electrode 2 from a high voltage switching circuit 9 controlled by a needle electrode control circuit 10, and the surface of the magnetic fluid 4 at the tip of the needle electrode 2 is charged with electricity.

On the other hand, a negative pulse voltage is applied from the voltage switching circuit 7 controlled by the recording signal control circuit 8 to the counter electrode 1 placed opposite to the needle electrode 2 via the recording paper 6, and the counter electrode 1 is brought into contact with the counter electrode 1. Electric charges are induced on the surface of the recording paper 6.

When the electric field formed by the charges on the surface of the magnetic fluid 4 at the tip of the needle electrode 2 and the charges on the surface of the recording paper 6 exceeds a certain value, the magnetic fluid flies due to Coulomb force and reaches the surface of the recording paper 6. Note that 11 and 12 are power supplies for the needle electrode 2 and counter electrode 1, respectively. A bias voltage is previously applied between the needle electrode 2 and the counter electrode 1 by a power source 13, and a pulse voltage is applied using this as a reference.

FIG. 2 shows the potential relationship between the needle electrode 2 and the counter electrode 1 during recording. In the figure, V _S is the voltage applied to the needle electrode 2, and V _G is the voltage applied to the counter electrode 1. Furthermore, V _B is a bias voltage.

FIG. 3 shows the configuration of the counter electrode 1. Counter electrodes 1 arranged at equal pitches on the polyimide film 14
and an input connector 15.

FIG. 4 is an enlarged view showing the positional relationship between the counter electrode 1 and the needle electrodes 2, and shows that a plurality of needle electrodes 2 correspond to one counter electrode 1.
In the above relationship, a pulse voltage is sequentially applied to the needle electrode 2 by matrix scanning, a recording signal is applied to the counter electrode 1 while scanning, and the magnetic fluid 4 is selectively ejected from the needle electrode 2 for recording.

Next, the protrusion of the magnetic fluid will be explained.

FIG. 5 is an enlarged view of the vicinity of the tip of the needle electrode 2. By magnetizing the needle electrode 2 with the magnet 3, a difference in magnetic force is generated between the needle electrode 2 and the gap between the needle electrodes. As a result, a large amount of the magnetic fluid 4 adheres to the tip of the needle electrode 2 where the magnetic force is strong, and it becomes difficult to adhere to the gap, forming a protrusion as shown in the figure.

The raised shape is used to control the amount of magnetic fluid 4 that adheres to the magnet 3, to maintain an appropriate distance l from the magnet 3 to the tip of the needle electrode 2, to give the magnet 3 an appropriate strength and shape, and to Controlled by using a ferrofluid of moderate magnetization. Specifically, the diameter of the needle electrode 2 is 50 to 100 μm, and the pitch of the needle electrode 2 is 125 to 125 μm.
The thickness of the magnet 3 is 1 to 3 mm, the distance l from the magnet 3 to the tip of the needle electrode 2 is 0.2 to 0.5 mm, and the magnetization of the magnetic fluid is 30 to 60 Gauss/100 Oersted.

The shape of the ridge is an important factor affecting recording quality. Figures 6a, b, and c are enlarged views of the protuberances. Figure a shows an example of an appropriate raised shape, where the tip radius γ and the raised height ε are appropriate values. Specifically, the diameter of the needle electrode 2 is 50 μm, and the pitch between the needle electrodes 2 is 50 μm.
At 125μ, the appropriate values are ε≒30μm and γ≒45μm.

Figure b shows the case where the amount of magnetic fluid attached to the magnet 3 is increased, the radius of the tip is large and the height of the protrusion is low. In this case, compared to the case shown in FIG. 2A, it is difficult to fly, the voltage required for flight is high, and even if it does fly, it is likely to fly from a valley where it should not fly, resulting in a decrease in recording quality.

Moreover, FIG. 3C shows a case where the amount of magnetic ink adhering to the magnet 3 is small, the tip radius is small and the height of the protrusion is large. In this case, it is easier to fly compared to the case shown in FIG. 2A, but the diameter of the recording dot is too small, resulting in recording with low density, which is also a disadvantage.

There are some nozzles that degrade the recording quality even if the optimum ridges as shown in FIG. The reason why this noise occurs is as follows.

As shown in Figure 4, multiple needle electrodes 2 correspond to 11 opposing electrodes, so when a recording signal is applied to the opposing electrode 1, it affects all of the multiple needle electrodes 2. . The total voltage applied between the recording needle electrode and the counter electrode at this time is V _T , and the total voltage applied between the non-recording needle electrode and the counter electrode is V′ _T. To explain this in FIG. 2, V _T =V _S +V _B +V _G V′ _T =V _B +V _G. The only difference between V _T and V' _T is V _S . Specifically, the values of V _S ≒400V, V _B ≒800V, and V _G ≒500V are used. The reason why V _B is set large here is that if an abnormally high voltage is used in the high voltage switching circuit,
This is because the number of circuits increases, accuracy decreases, and costs increase.

In this way, V _T ≒1700V, V′ _T ≒1300V, V _T /
V′ _T ≈1.3, and the ratio of the needle electrode 2 that records to the needle electrode that does not record, the so-called S/N, is small. Due to processing and assembly conditions, variations in shape occur between the formed ridges, so voltage pulses are not applied to the needle electrodes from the ridges that have a shape that makes them easy to fly due to the variations in the shape of the ridges. It may fly even when not in use.

This noise, together with other noises, significantly degrades the recording quality and has been a problem.

The present invention solves the above-mentioned non-selected point noise by making the magnetic fluid fly only from the ridge at the tip of the needle electrode that should be reliably recorded even if there is some static variation in the shape of the ridge. , an attempt is made to obtain a magnetic fluid recording device with good recording quality.

An embodiment of the present invention will be described below with reference to FIGS. 7 to 9.

FIG. 7 is a schematic configuration diagram of a magnetic fluid recording device according to an embodiment of the present invention, FIG. 8 is a partially enlarged view of the same device, and FIG. 9 is an explanatory diagram of the operation of the same device. 1 in the diagram
13 to 13 are the same as those shown in FIGS. 1, 3, and 4, and are constructed and arranged in the same manner.

As described above, the recording method involves applying a recording signal to the counter electrode 1 while sequentially applying a pulse voltage to the needle electrode 2 by matrix scanning, and causing the magnetic fluid to fly from the bulge at the tip of the needle electrode to perform recording.

In the figure, reference numeral 16 denotes a plurality of auxiliary electrodes made of a non-magnetic material, which are arranged in the vicinity of the needle electrode 2 in a staggered configuration with the needle electrode 2, as shown in FIG. In other words, the needle electrode 2 is arranged between adjacent auxiliary electrodes.

And the auxiliary electrode is in contact with the magnetic fluid. When the number of needle electrodes 2 is n, the number of auxiliary electrodes 16 is (n+1).
There are individual auxiliary electrodes 16. The most desirable position of the auxiliary electrodes 16 is to place them in the center of the adjacent needle electrodes 2, except for the two at both ends.
It is desirable to position the needle electrodes 2 at positions separated by a pitch. The width of one auxiliary electrode is w<P, where w is the width and the pitch of the needle electrode 2 is P.

Further, it is desirable that the area of the surface of the auxiliary electrode facing the needle electrode 2 be as large as possible, but it is desirable that the upper end of the auxiliary electrode be placed near the upper end of the magnet 3.

In FIG. 7, all the needle electrodes 2 and the auxiliary electrode 16
A DC voltage is applied between all electrodes by a power source 17 so that the counter electrode 1 and the auxiliary electrode 16 have potentials in the same direction with respect to the needle electrode 2.

In this way, when a voltage is applied between the needle electrode 2 and the auxiliary electrode 16, a downward force acts on the entire bulge at the tip of the needle electrode 2, the ridge deforms, the tip radius becomes smaller, and the bulge The height becomes higher, and the bump becomes easier to fly compared to the bump before the voltage was applied as explained in FIG. The reason will be explained in more detail using FIG.

FIG. 9 is an enlarged view of the vicinity of the tip of the needle electrode 2, and a sectional view of the center of the needle electrode 2. Needle electrode 2 and auxiliary electrode 16
When a voltage is applied between it, it becomes a capacitor and forms an electric field.

The electric field is strongest in the region within the broken line 18 in the figure, and electrostatic attraction force acts from both electrodes so that the liquid level of the magnetic fluid 4, which is a dielectric, comes to the broken line 18.

The electrostatic attraction force acts on all of the magnetic fluid 4 between the electrodes 16 and 2, but since it is held by the magnetic force of the magnet 3 and needle electrode 2, the magnetic force of the place held by strong magnetic force Fluid 4 is difficult to work with. Regarding the ridges, as mentioned above, the magnetic holding force is strong in the mountain parts, while the magnetic holding force in the valley parts is very weak compared to the mountain parts. Therefore, the magnetic fluid 4 in the valley portion moves due to the electrostatic attractive force, and as a result, the radius of the tip of the ridge becomes small and the height of the ridge becomes high. In terms of FIG. 6, if the bump before voltage application is shown as b in the same figure, after voltage application, the bump becomes easier to fly as shown in figure a.

In order to make the electrostatic attractive force work effectively, auxiliary electrodes are placed in the ridges and valleys where the magnetic holding force is weak.

The potential direction of the auxiliary electrode 16 is set in the same direction as that of the counter electrode 1 with respect to the needle electrode 2. The inventors have experimentally confirmed that when the potential is set in the opposite direction, the electrostatic attraction force does not work, and the deformation of the bulges as described above does not occur.

According to this embodiment, a magnet for controlling the protrusion shape;
Processing, assembly, etc. of the needle electrode etc. becomes easier, and the permissible range of magnetization of the magnetic fluid can be widened.

Next, another embodiment of the present invention will be described using FIGS. 10 to 12.

FIG. 10 is a schematic diagram of a magnetic fluid recording device according to another embodiment of the present invention. The basic configuration is the same as that of the previous embodiment shown in FIG. The correspondence between the counter electrode 1, the needle electrode 2, and the counter electrode 1 is the same as that of the previous embodiment. As described above, the recording method is to sequentially apply a pulse voltage to the needle electrode 2 by matrix scanning, apply a recording signal to the counter electrode 1, and make the magnetic fluid 4 fly from the bulge at the tip of the needle electrode 2 to be recorded. Do this.

The positional relationship between the needle electrode 2 and the auxiliary electrode 16 is as follows.
This is the same as in the previous embodiment shown in the figure.

A negative pulse voltage is applied to the auxiliary electrode 16 with respect to the needle electrode 2 by a high voltage switching circuit 18 controlled by an auxiliary electrode control circuit 19.

When applying a positive pulse voltage to the counter electrode 1 with respect to the needle electrode 2, that is, the power supplies 11, 12, 13
When the positive and negative polarities of are opposite to those shown in FIG. 10, a positive pulse voltage is also applied to the auxiliary electrode 16. Auxiliary electrode 1
6 is set to a potential in the same direction as the counter electrode 1 with the needle electrode 2 as a reference.

FIG. 11 is a timing chart of the pulse voltage applied to the auxiliary electrode 16.

When a pulse voltage is applied to one of the needle electrodes 2, pulse voltages are simultaneously applied to the auxiliary electrodes 16 located on both sides of the needle electrode 2. Since pulse voltages are sequentially applied to the needle electrodes 2 in a matrix scan, voltage pulses are sequentially applied to each pair of adjacent electrodes of the auxiliary electrodes 16 under the conditions shown in FIG. 11 in a matrix scan.

When a voltage is applied as described above, the shape of the protrusion changes as shown in FIG. FIG. 12 shows the state when a voltage pulse is applied to the needle electrode in the figure.
When a voltage is applied between the needle electrode and the auxiliary electrodes 16-2 and 16-3, the ridges and valleys on both sides of the needle electrode are attracted in the direction of the arrow, forming a bulge as shown by the broken line in the figure.

The reason for this is the same as that explained in the previous embodiment.

The ridges initially set statically are all shaped into the shape shown in FIG. 6b by controlling the amount of magnetic fluid attached to the magnet 3, so that they are less likely to fly than the optimal ridges shown in FIG. 6a.

Then, when a pulse voltage is applied to the needle electrode 2 at the timing and direction shown in FIG. 11, and at the same time, a pulse voltage is also applied to the auxiliary electrodes 16 on both sides of the needle electrode 3, the protrusion occurs only in the part of the needle electrode 2 to which the pulse voltage is applied. As shown in FIG. 12, the radius of the tip becomes smaller and the height of the ridge becomes higher, making it easier to fly compared to other ridges, resulting in an appropriate ridge shape in terms of recording quality.

In advance, the total voltage applied between the needle electrode 2 and the opposing electrode (the above-mentioned V _T ) for controlling the flight is set to a voltage for an appropriate protrusion shape. By doing this, the difference in ease of flight between the protrusions of the needle electrode 2 that should fly and other protrusions of the needle electrode 2 that should not fly is
In addition to the difference in the total voltages V _{T and} V' _T mentioned above, there is also a difference in shape, so this is several steps better than the conventional case of statically forming the optimum bump.

According to this embodiment, in addition to the effects of the embodiments described above, it is possible to prevent non-selected point noise due to flying from bumps that should not be recorded, and to obtain a magnetic fluid device with stable and good recording quality.

Note that although a flat plate is shown as the shape of the auxiliary electrode 16, it may also be cylindrical or prismatic.

Further, in the embodiment, a configuration is shown in which the magnet 3 is brought into direct contact with the needle electrode 2, but the present invention is also applicable to an external magnet system in which the needle electrode is magnetized without directly contacting the needle electrode 2. There isn't.

As described above, according to the present invention, there is provided a magnetic fluid recording device that can deform the magnetic fluid into a raised shape that makes it easier to fly by providing an auxiliary electrode, and can obtain a good and stable recorded image. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a conventional magnetic fluid recording device, Fig. 2 is a timing chart showing the potential relationship between the needle electrode and the counter electrode of the device, and Fig. 3 is a diagram of the counter electrode of the device. FIG. 4 is an enlarged view showing the positional relationship between the opposing electrode and the needle electrode of the device, and FIGS. 5 and 6 are explanatory diagrams showing the raised state of the magnetic fluid of the device. 5A is a plan view of the same portion, and FIG. 5B is a sectional view of the same. FIG. 7 is a schematic configuration diagram of a magnetic fluid recording device that is an embodiment of the present invention, FIG. 8 is an enlarged view of the vicinity of the needle electrode of the same device, and FIG. 9 is a plan view. An explanatory diagram showing the operating principle of the device, FIG. 10 is a schematic configuration diagram of a magnetic fluid recording device according to another embodiment of the present invention, and FIG. 11 shows outputs of each part between the needle electrode and the auxiliary electrode of the device. The timing chart of FIG. 12 is an explanatory diagram of the operation of the device. 1... Opposing electrode, 2... Needle electrode, 3... Magnet, 4... Magnetic fluid, 5... Tank, 6... Recording paper, 11, 12,
13, 17...power supply, 16...auxiliary electrode.

Claims (1)

[Claims] 1. A plurality of needle electrodes made of a magnetic material, a protuberance forming means for magnetizing the needle electrodes and adhering a magnetic fluid to the tips of the needle electrodes to form protuberances, and a supply means for supplying the magnetic fluid to the tips of the needle electrodes. a counter electrode placed opposite to the needle electrode with a recording paper interposed therebetween; a plurality of auxiliary electrodes arranged near the tip of the needle electrode so as to be in contact with the magnetic fluid; and between the needle electrode and the counter electrode. The first one applies a voltage according to the recording signal.
and a second voltage applying means for applying a voltage between the needle electrode and the auxiliary electrode, and configured such that the auxiliary electrode is staggered with respect to the needle electrode. and the potential direction of the voltage applied to the auxiliary electrode is based on the needle electrode,
The electric potential is set in the same direction as the counter electrode, and when a pulse voltage is applied to one of the needle electrodes, pulses are applied to auxiliary electrodes on both sides of the needle electrode in synchronization with this. magnetic fluid recording device.