JPH0130627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a direct recording method known under the name of powder contrastography. This recording method has been proposed, for example, in US Pat.

First, the structure and operation of this type of direct recording device will be explained with reference to FIG.

A donor drum consisting of a magnetic counter electrode 1 with fine irregularities formed on its circumferential surface has a magnet roll 2 in contact with it at one point on its circumferential surface, and a magnet roll 2 at another point in the drum traveling direction a of the same roller 2. In this case, the recording electrode 3 is in contact with the donor drum with a predetermined gap 4 in between, and the fed recording paper 5 passes through the gap 4. Here, the recording paper 5 refers to the sheet. Refers to a recording medium such as a shape or a ribbon shape.

A magnet 6 and a magnet 7 are respectively installed inside the roll 2 and the drum that rotate continuously in the same direction, and the magnets 6 and 7 have magnetic poles of different polarity facing each other. On the other hand, a hopper 9 for powder toner (also referred to as magnetic toner) 8 having magnetism and conductivity is opened at the top of the roll 2 .

Further, an output voltage from a voltage generator E that converts required image information into an electric signal is applied to the recording electrode 3, and a counter electrode 1 facing the recording electrode 3 is grounded.

In the recording device configured in this way, the hopper 9
The magnetic toner 8 that has fallen onto the roll 2 from the magnets 6 and 7 adheres to the uneven circumferential surface of the counter electrode 1 in a tower shape due to the magnetic field between the magnets 6 and 7, and is transported in the direction a by the rotation of the drum, and during its movement, the magnetic toner 8 is Pass through 4.

On the other hand, in this gap 4, an electric field corresponding to image information is generated between the recording electrode 3 and the counter electrode 1 based on the application of the signal voltage to the recording electrode 3, and due to the action of this electric field, Magnetic toner 8 is selectively attracted and adhered to the recording paper 5, and a toner image corresponding to the signal information is recorded on the recording paper 5.

By the way, in a conventional general direct recording device that operates in this manner, the interval dimension of the gap 4 is set to a sufficient size in order to prevent the background smudge phenomenon, that is, the unnecessary adhesion of the toner 8 when a signal is applied to the non-image area. For this reason, it is necessary to increase the signal voltage corresponding to the image area to 1KV or more.Also, to avoid increasing the signal voltage, it is necessary to increase the signal voltage to 1KV or less. As shown in Figure 2, when using a 3D printer, the amount of toner adhering to the image decreases, making it difficult to obtain sufficient contrast and resolution, resulting in a decrease in image quality. There was a problem that I didn't have.

The present invention solves the above problems by generating a bias magnetic field in the gap between the recording electrode and the counter electrode and adding this to the signal electric field. Another object of the present invention is to provide a direct recording method that allows toner recording of good image quality using a low signal voltage.

The present invention will be described below based on illustrated embodiments.

First, in the recording method as the first embodiment, as shown in FIG. Permanent magnets 10 are installed on both sides of the electrode 3. For example, in the illustrated example, the magnets 10 are Ba ferrite rubber magnets with a surface magnet density of 500 gauss.

However, although 600V is used as the signal voltage in this case, the results when a toner image was experimentally attached to the recording paper 5 using this method showed that the image density =
1.0, and a good recording effect with a resolution of 6 lines/mm was confirmed.

This means that, as shown in the figure, the magnetic toner 8
It is shown that the magnetic toner 8 is attracted by the magnetic field generated by the permanent magnet 10 to form a tall tower shape, and as a result, a sufficient amount of magnetic toner 8 adheres to the recording paper 5 even with a weak signal electric field.

In addition, in the conventional method shown in Figure 1, the result when using a low signal voltage of 600V is that image density =
0.3, a recording effect of only about 2 lines/mm could be obtained.

In addition, in the above configuration, a permanent magnet is used to generate the magnetic field, but instead of this, a DC electromagnet is used to make the strength of the bias magnetic field variable, thereby changing the magnetic permeability of the toner 8 and the signal voltage E. If the strength of the magnetic field can be adjusted in accordance with the rate, etc., it will be possible to further reduce the signal voltage, and even if the image signal is accompanied by background stains, it will be possible to Good recording quality can be obtained.

Next, in the recording method as the second embodiment, as shown in FIGS. 4 and 5, a large number of recording needles 14 of the recording electrode 11 held by the shield 13 via the insulator 12 are formed using magnets. When recording is performed with this configuration, a magnetic field is generated that attracts the toner 8 toward the electrode 11 due to the magnetic force of the recording needle 14, and is superimposed on the signal electric field. As in the method, good quality toner images are recorded using low voltage image signals.

Furthermore, in the recording method as the third embodiment, as shown in FIG. A magnet 20 is attached that passes completely in the direction, and is held by an insulator 21.
When a recording operation is performed with this configuration, a magnetic field is generated in the same manner as described above due to the magnetic force of the magnet 20, and the same effect is produced.

It should be noted that it is unnecessary to arrange a magnet on the recording paper 5 feeding side of the recording electrode 15 because it will cause disturbance of the recorded image.In addition, it is also possible to strengthen the bias effect by using a magnetic material for the recording needle. It is possible.

Finally, in a recording method as a fourth embodiment, as shown in FIG. 7, two rows of recording needles 24 are arranged in a staggered manner in the front and back in a deep shield 23, and recording electrodes 26 are arranged in a deep shield 23. In addition, a plurality of magnets 25 are arranged in a row along the advancing direction on the recording paper feeding side of the recording needle in the back row, and when recording is performed with this configuration, the magnetic force of each magnet 25 is Due to the action, a magnetic field is generated in the same manner as described above, and a similar effect is produced.

In this way, when the methods of each of the above embodiments are used, toner recording of good image quality can be obtained using a low signal voltage.

As described above, according to the direct recording method of the present invention, a magnet is installed in contact with the recording electrode side of the recording paper, thereby generating a magnetic field in a direction that attracts magnetic toner, and converting this into a signal electric field. By polymerizing the toner and recording the toner surface image on the recording paper,
A recorded image of good quality can be obtained using a low signal voltage, thus producing the effect of improving the recording efficiency of the direct recording method.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional general direct recording device, FIG. 2 is an enlarged view of the portion shown in FIG. 1, and FIG. 3 is a diagram of a direct recording method showing a first embodiment of the present invention. A schematic diagram of the main parts, corresponding to Figure 2, Figure 4
The figure is a schematic diagram of the recording method showing the second embodiment, and is a diagram corresponding to the above-mentioned part. FIG. 5 is a bottom view at the arrow ▽ in FIG. 4, and FIG.
FIG. 7 is a schematic diagram of a recording method showing the fourth embodiment. 1... Counter electrode, 3, 11, 15, 26... Recording electrode, 4... Gap, 5... Recording paper, 8... Magnetic toner, 10, 20, 25... Magnet, 14... As magnet Recording needle.

Claims (1)

[Claims] 1. A recording paper is passed through a gap between a recording electrode and a counter electrode that holds magnetic toner on the surface and moves relative to the recording electrode, and an image signal is applied to the recording electrode. In a direct recording method, a toner image is deposited on the recording paper by generating an electric field corresponding to the signal in the gap,
A direct recording method, characterized in that a magnetic field is applied to the signal electric field in the gap by a magnet placed opposite to the recording electrode side of the recording paper. 2. The direct recording method according to claim 1, wherein the magnetic field is added by the action of a permanent magnet or an electromagnet installed adjacent to the recording electrode. 3. The direct recording method according to claim 1, wherein the magnetic field is added by the action of a recording needle formed of a magnet of the recording electrode. 4. The direct recording method according to claim 1, wherein the magnetic field is added by the action of a magnet placed close to the recording needle on the magnetic pole surface of the recording electrode.