JPS6139907B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic recording method, and particularly to a recording method that reduces recording unevenness that occurs in each block of a multi-needle electrode.

There are two types of electrostatic recording: a double-sided control type in which a needle electrode and a back electrode are provided between the recording medium, and a single-sided control type in which a needle electrode and an auxiliary electrode are provided on one side of the recording medium.

The multi-needle electrode (multi-tylus) is divided into multiple blocks, and voltage is applied in the order of the blocks.
When a voltage of opposite polarity is applied to the back electrode or the auxiliary electrode, the recording medium is charged and an electrostatic latent image is formed. Electrostatic recording is performed by developing and fixing this latent image.

By the way, it is known that in the case of a type in which a multi-needle electrode is divided into a plurality of blocks (groups) for recording, the recording state differs between the center and the end of the needle electrode group. Such a difference in recording state naturally causes recording unevenness. That is,
When recording on the recording medium of the base (base paper) placed under the electrode by applying a voltage to the needle electrode that constitutes the recording electrode and the auxiliary electrode in its vicinity,
The lower the base resistance between the needle electrode and the auxiliary electrode, the better the recording conditions. Since resistance is proportional to distance and resistivity and inversely proportional to cross-sectional area, the closer the distance between the needle electrode and the auxiliary electrode, the better the conditions. In addition, the capacitance of the air between the needle electrode and the recording medium is smaller than the capacitance of the air between the auxiliary electrode and the recording medium, and the capacitance of the dielectric layer between the needle electrode and the base is smaller than that between the auxiliary electrode and the base. When the capacitance is smaller than the capacitance of the dielectric layer, it is possible to increase the voltage across the capacitance to improve the discharge efficiency (described later with reference to FIGS. 1a and 1b). In this way, it is known that the discharge efficiency changes depending on the electric field in and around the needle electrode. Therefore, since the relative position with respect to the auxiliary electrode is different between the center and the ends of the needle electrode group, when voltage is applied to the needle electrodes in the group at the same time, the electric field is different between the center and the ends of the group. It can be seen that there is a difference between As a result, there is a difference in the recording state between the center and the edges. That is, assuming that the area of the needle electrode is constant, the discharge conditions vary depending on the distance between the needle electrode and the auxiliary electrode or the area of the auxiliary electrode.

As a method for reducing recording unevenness in double-sided control type, as shown in Japanese Patent Application Laid-Open No. 52-31745,
When voltage is applied in the first half and second half of a block, a method has been proposed in which the needle electrode of the first half or the second half of the block to be recorded is scanned from both ends toward the center.

According to this method, it is possible to flatten the potential distribution of the conductive layer of the recording medium for each 1/2 block of the multi-needle electrode, prevent uneven recording, and improve image quality. An increase in the number of memory circuits is inevitable.

On the other hand, even in the single-sided control type, recording unevenness still occurs for each group, although it is slightly different from the recording unevenness in the double-sided control type. Therefore, if the method for reducing recording unevenness described above is adopted, it is possible to make the unevenness less noticeable, but since signals are input serially within the group, the recording speed naturally decreases. In order to increase the recording speed, it is inevitable to increase the memory.

The phenomenon of recording unevenness is particularly noticeable when recording solid black images, and when recording thin lines such as characters or images covering a narrow area,
It's hardly noticeable.

An object of the present invention is to provide an electrostatic recording method that reduces recording unevenness occurring in each block of multi-needle electrodes without reducing recording speed or increasing memory.

In the electrostatic recording method of the present invention, at least one row of multi-needle electrode groups divided into a plurality of groups and auxiliary electrode groups arranged on one side or both sides of the multi-needle electrode corresponding to the group are sequentially arranged from one end. In an electrostatic recording method that forms an image according to calligraphic information by driving, the distance between the auxiliary electrode and the needle electrode is set to a small value in the front in the scanning direction for each group.
Either set the area to a larger value at the rear, or set the area for each needle electrode when dividing the auxiliary electrodes perpendicular to the needle electrode row into a larger value at the front and a smaller value at the rear in the scanning direction for each group. The feature is that a binary potential is applied to the auxiliary electrode by using either the auxiliary electrode or both at the same time. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1a and 1b are diagrams of the principle of the present invention in a single-sided control type recording electrode.

The most basic one-sided control type recording electrode has the structure shown in FIG. 1a, and its equivalent circuit is shown in FIG. 1b.

In FIG. 1a, STY is a needle electrode, SEG is an auxiliary electrode on one side, Q is a dielectric layer of the recording medium, and B is a base paper. Also, in Figure 1b, C ₁
is the air capacitance between the needle electrode and the dielectric layer, C ₂ is the air capacitance between the auxiliary electrode and the dielectric layer, C ₃ is the capacitance of the dielectric layer between the needle electrode and the base, C ₄ is the auxiliary electrode and The capacitance of the dielectric layer between the bases, R is the resistance of the base between the needle electrode and the auxiliary electrode.

When a voltage of Vsty is applied to the needle electrode STY and a voltage of Vseg is applied to the auxiliary electrode SEG, recording conditions are improved if the resistance R is small, as is clear from FIG. 1b. Since the resistance R is proportional to the resistivity ρ and the distance 1, and inversely proportional to the cross-sectional area A, the conditions become better as the distance between the needle electrode STY and the auxiliary electrode SEG becomes shorter.

Furthermore, the capacitances C ₁ to _{C 4} in Figure 1b are proportional to the area S and inversely proportional to the thickness (distance) d;
Since the conditions are the same for both the needle electrode STY and the auxiliary electrode SEG, it can be considered that the capacitances C ₁ to _{C 4} are proportional only to the area S.

Furthermore, since the voltage V is compared to the charge ρ and is inversely proportional to the capacitance C, if q is constant, the capacitance C
The smaller the voltage V, the larger the voltage V becomes. As a result, in FIG. 1b, if C ₁ <C ₂ < or C ₃ <C ₄ , the voltage across the capacitances C ₁ and C ₃ can be increased and the discharge efficiency can be improved. Here, assuming that the area of the needle electrode STY is constant, the area of the auxiliary electrode SEG that is in contact with or close to the recording medium needs to be large. Therefore, as a single-sided control type recording electrode, a needle electrode is used.
It is important that the ratio of the contact area between STY and the auxiliary electrode SEG be 100 or more.

FIG. 2 is an explanatory diagram of recording unevenness and an electrode arrangement diagram.

When the needle electrode STY and the auxiliary electrode SEG are arranged as shown in FIG. 2a or c and recording is performed using single-sided control, a concentration distribution with respect to distance as shown in FIG. 2b is obtained. In other words, in Fig. 2a, when applying voltage in the direction of the arrow, there are two ways to apply voltage to the needle electrode group STYG: one is to apply it to four needles at a time, and the other is to apply it to each needle one by one. However, here, as an example in which the concentration changes significantly, a case will be described in which voltage is applied one by one one by one. On the other hand, a voltage of opposite polarity to that of the needle electrodes is simultaneously applied to two auxiliary electrodes SEG arranged above and below each needle electrode group STYGP. Now, when voltage application moves to the second needle electrode group STYGP from the left, a reverse voltage is applied to the second upper and lower auxiliary electrodes SEG. When a positive voltage is applied to the leftmost needle electrode of the second group from the left, the needle electrode STY of the leftmost group, which is the closest
Since the recording medium in the vicinity of the recording medium is charged with positive electrostatic charges, the influence of these charges is canceled out, the charging ability is reduced, and as a result, the recording density is considered to be the lowest. Next, when a positive voltage is applied to the second needle electrode of the second needle electrode group STYGP from the left, it is also influenced by the leftmost needle electrode group STYGP, but the degree of influence is inversely proportional to the square of the distance. As it becomes smaller, there is a slight offset, and as a result, the recording density becomes higher than before. Note that, at this time, the second needle electrode is also affected by the charge caused by the first needle electrode of the same group, but this is negligibly small compared to the amount of charge on the recording medium of the adjacent group. Next, when a positive voltage is applied to the third needle electrode, the influence of the leftmost group becomes slight, and the recording density becomes even higher than before.
When a positive voltage is applied to the fourth needle electrode, the recording density is the highest because it is hardly influenced by the leftmost group. Next, at the same time as the voltage applied to the second group is cut off, a positive voltage is applied to the leftmost needle electrode of the third group, and a negative voltage is applied to the third upper and lower auxiliary voltages SEG. Ru. At this time, as described above, the recording medium near the second group of needle electrodes is charged with positive electrostatic charge, so it is affected to the maximum and the recording density decreases. This is likely to be the lowest. When a positive voltage is sequentially applied to the second and third needle electrodes of the third group, they are still affected by the residual electrostatic charges of the adjacent groups, but as the distances become farther apart, the recording density gradually increases. , 4
At the time of application of the th needle electrode, there is almost no influence from adjacent groups, and the recording density is the highest. In this way, a curve as shown in FIG. 2b will result. Note that at the time when the voltage is applied to the leftmost needle electrode, there is no adjacent group, so there is no influence, and there is no decrease in concentration as shown in FIG. 2b. Furthermore, in the method of simultaneously applying voltage to the four needle electrodes in each group as shown in FIG. 2a, the difference in height of the recording density curve is smaller than in the method of sequentially applying voltage.

In the case of Figure 2c, during the period when voltage is applied to the four needle electrodes in the leftmost group, a voltage of opposite polarity to the needle electrodes is applied to the leftmost and second four upper and lower auxiliary electrodes. applied. Next, during a period in which voltage is applied to the second group of needle electrodes from the left, voltages of opposite polarity are applied to the second and third upper and lower auxiliary electrodes. In this way, voltage is applied to the auxiliary electrodes one by one, but in this case as well, the second
Based on the same principle as in Figure a, the recording density curve becomes as shown in Figure 2B. In addition, the needle electrode
There are four STYs and one group is STYGP.
This unevenness in recording density also occurs in double-sided control.

FIGS. 3 to 8 are arrangement diagrams of recording electrodes showing examples of the present invention, respectively, and show one in which one side is controlled and auxiliary electrodes are arranged on both sides.

In FIGS. 1a and 1b, the reason why recording conditions (discharge conditions) change when the distance between the auxiliary electrode and the needle electrode and the area of the auxiliary electrode differ is explained.

The present invention utilizes this principle to reduce recording unevenness.

In FIG. 3, the distance between the auxiliary electrode and the needle electrode is set to a small value d ₂ at the front in the main scanning direction X, and a large value d ₁ at the rear. As shown in FIG. 2b, the recording density increases at the rear of the needle electrode group STYGP in the main scanning direction _X. Therefore _, as shown in FIG. As the recording efficiency in front of the area increases more than the recording efficiency in the area behind it, recording unevenness decreases.

In Fig. 4, the distance between the auxiliary electrode and the needle electrode on only one side of the arrangement shown in Fig. 3 is changed, and although d ₂ < d ₁ , the distance on only one side is changed. Since only changes are required, manufacturing is easier than in the case of FIG. 3.

Of course, if the auxiliary electrode is arranged only on one side, the electrode is only on the upper stage of FIG. 4.

In Fig. 5, the closest distance between the needle electrode and the auxiliary electrode is kept the same, but the area of each auxiliary electrode divided perpendicularly to the needle electrode array is changed to correspond to one needle electrode. be. As explained in FIGS. 1a and 1b, the larger the area of the auxiliary electrode close to the recording medium, the more the discharge efficiency improves. Therefore, the recording density unevenness shown in FIG. 2b is caused by the fifth
By arranging the auxiliary electrodes in the shape shown in the figure, the recording efficiency in front of the needle electrode group is higher than that behind it, so correction is made.

FIG. 6 shows a modification of FIG. 5, in which auxiliary electrodes with different areas are arranged every other time.

In Fig. 6, ○ marks are auxiliary electrodes with constant area;
The X marks are auxiliary electrodes with different areas.

Of course, as shown in FIG. 4, it is also possible to arrange elements with different areas only on one side.

In the case of FIG. 6, there is an advantage that the electric fields are averaged at the auxiliary electrodes on both sides of the needle electrode array.

In Figure 7, the distance from the auxiliary electrode to the needle electrode and the area of each auxiliary electrode divided perpendicularly to the row of needle electrodes are made different to achieve a synergistic effect. It is ivy. In this case, since both effects are achieved, it can be implemented without changing the shape or distance of the auxiliary electrode much, but it is somewhat difficult to manufacture.

In FIG. 8, the aim is still to achieve a synergistic effect, but the auxiliary electrode is composed of a plurality of conductors so that the distance or area, as well as the distance and area, can be changed freely. Each of the plurality of conductors is insulated.

In the case of FIG. 8, among the plurality of conductors of the auxiliary electrode, the shaded portion is connected to the earth potential GND, while the voltage V _SEG is applied to the other portion CND.
In this way arbitrary auxiliary electrode shapes and varying distances to the needle electrode can be obtained.

Manufacturing can be done relatively easily by sandwiching or embedding multiple metal blocks in an insulator to create auxiliary electrodes and sandwiching these on both sides of the needle electrode array. . Moreover, even if the recording conditions change due to changes in the external environment during recording or the impedance of the recording paper, it is easy to change the distance, area, etc. of the auxiliary electrode, so recording unevenness can be stably reduced. can be done.

As explained above, according to the present invention, the distance between the auxiliary electrode and the needle electrode is made different, the area of the auxiliary electrode divided in the vertical direction of the needle electrode row is made different, or both the distance and the area are made different. By making them different, it is possible to reduce the recording unevenness that occurs for each block of multi-needle electrodes, and in this case, there is no need to reduce the recording speed or increase the memory.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of the present invention in a single-sided control type recording electrode, FIG. 2 is an explanatory diagram of recording unevenness corresponding to the electrode arrangement, and FIGS. 3 to 8 are recordings showing each embodiment of the present invention, respectively. FIG. 3 is a layout diagram of media. CND: conductor, GND: earth potential, STY: needle electrode, SEG: auxiliary electrode, Q: dielectric layer, B: base paper (base), Vsty, Vseg: applied voltage, STYGP: needle electrode group, d ₁ , d ₂ : Distance between auxiliary electrode and needle electrode.

Claims (1)

[Claims] 1. By sequentially driving from one end at least one row of multi-needle electrode groups divided into a plurality of groups and auxiliary electrode groups arranged on one side or both sides of the multi-needle electrodes corresponding to the group, calligraphic information is generated. In an electrostatic recording method that forms a corresponding image, the distance between the auxiliary electrode and the needle electrode is set to a small value in the front and a large value in the rear in the scanning direction for each group, or the distance is set to a value corresponding to each needle electrode. When the auxiliary electrodes are divided perpendicularly to the needle electrode array, each area of the auxiliary electrodes can be set to a larger value in the front in the scanning direction and a smaller value in the rear in the scanning direction, or both can be used simultaneously. An electrostatic recording method characterized by applying a binary potential to.