JPH0630907B2 - Electrostatic recording method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrostatic recording method.

BACKGROUND ART In electrostatic printing and the like, it is possible to generate ions with a high current density, extract the ions, and selectively apply the ions to a member to be charged to charge the member in an image-like manner.
It is known from the publication No. 4155093. In the ion generator used in this device, a dielectric, a plurality of first electrodes fixed to one side of the dielectric and extending in a first direction, and a first electrode fixed to the other side of the dielectric are provided. A plurality of second electrodes extending in a direction intersecting the direction, and the plurality of first electrodes and the plurality of second electrodes form a matrix. By applying an alternating voltage between the first electrode and the second electrode corresponding to the selected portion of this matrix, positive and negative ions are generated in the vicinity of the second electrode corresponding to that portion. The generated ions can be selectively extracted to charge the member to be charged. Therefore, it is possible to perform electrostatic recording by dots by selectively driving the electrodes having the matrix structure.

Although electrostatic recording by this method is considered to be useful, there is a drawback that the size of one dot of recording is not constant and varies with the currently known ones, so that a uniform latent image cannot be formed. There is.

SUMMARY OF THE INVENTION Therefore, the present invention has clarified the cause of dot size variation in the electrostatic recording method of the above-described type, and by eliminating this, it is possible to form dots of a uniform size, and a uniform latent image is formed. An object is to provide an electrostatic recording method capable of forming an image.

SUMMARY OF THE INVENTION The present inventor has a plurality of first electrodes extending in a first direction,
A second electrode extending in a second direction different from the first direction and forming a matrix with the first electrode; and a second electrode provided on the side opposite to the first electrode with respect to the second electrode and corresponding to the matrix. A third electrode having an opening, a first dielectric between the first electrode and the second electrode, and a second dielectric between the second electrode and the third electrode. The body has openings corresponding to the matrix, and an alternating voltage is applied between the first electrode and the second electrode to generate ions by the discharge between the second electrode and the first dielectric surface. Cause of non-uniformity in dot size in an electrostatic recording method in which a potential difference between the second electrode and the third electrode causes extraction from the opening of the third electrode to form a charge pattern of charge dots on the surface of the recording medium by the ions To form a single charge dot The effective ionic number of occurrences of Rusai 1
By setting it to 0 or more, the dot size becomes uniform,
Therefore, it is possible to form a uniform latent image.

EXAMPLE FIG. 1 is a sectional view of an electrostatic recording head used in the electrostatic recording method of the present invention, and FIG. 2 is a perspective view of the same.

This electrostatic recording head 1 is shown in the lateral direction of FIG. 1 (first direction).
A first electrode 11 which is an induction electrode extending in the first direction and a second electrode 12 which is a discharge electrode extending in a second direction different from the first direction
(Finger electrodes), and these electrodes form a matrix when viewed from above in FIG. There is a third electrode 13 on the opposite side of the second electrode 12 from the first electrode 11,
It has a plurality of openings corresponding to the matrix. The first electrode 11 and the second electrode 12 and the first dielectric 1 between them
Hold 4 That is, the first electrode 11 and the second electrode 12 are fixed to the respective surfaces of the first dielectric body 14. The second electrode 12 and the third electrode 13 also sandwich the second dielectric 15 between them. The second dielectric 15 has openings 16 corresponding to the plurality of openings of the third electrode 13. By selectively applying an alternating voltage between the plurality of first electrodes 11 and the second electrodes 12 of the ion generating device of this configuration, a positive electrode is provided in the vicinity of the second electrode 12 corresponding to the selected portion of the matrix.・ Negative ions are generated. A bias voltage is applied between the second electrode 12 and the third electrode 13, and only ions having a polarity determined by the polarity are extracted from the positive and negative ions, and these ions pass through the openings 16 and 17. A member to be charged, which is a recording material (not shown) provided facing the opening 17 is charged. In this way, a dot latent image can be formed on the recording material by selectively driving the plurality of first electrodes 11 and the second electrodes 12.

Before explaining the electrostatic recording method of the present invention using this recording head, the cause of the variation in dot size which the present inventors have clarified will be described in detail. FIG. 3 shows the first electrode 1
1 shows a temporal change in a current flowing between the first electrode and the second electrode 12. Multiple times (typically 2
The sharp spike-shaped current that occurs is due to the discharge that generates the positive and negative ions. It is considered that this discharge is triggered by radiation or the like in a place where there is a strong electric field, and the time of discharge occurrence is random and not constant. If you repeat the discharge current waveform over and over,
As shown in the figure, it is understood that the time of occurrence of discharge varies greatly.

The inventor thinks that the discharge generation time differs for each cycle in this way, and therefore the discharge voltage is different, and therefore the amount of ions extracted and passing through the opening 17 is different every time, which results in a non-uniform dot latent image. I thought it would be an obstacle to getting. Then, in order to eliminate this non-uniformity, it is conceivable to reduce the amount of discharge at one time and generate ions a plurality of times per dot, instead of making dots at one large discharge. The inventor repeated an experiment to reduce the discharge and increase the number of times, and found that the number of discharges was 10 or more, the dot diameter variation was extremely small.

The electrostatic recording method of the present invention will be described below.

In FIG. 1, an alternating voltage having a frequency of 3 MHz is applied between the first electrode 11 and the second electrode 12, and a charged member (not shown), which is a recording medium, is provided below the recording head with the third electrode 13. It is installed opposite to. This charged member is 12
Move in inches / second. The first electrodes 11 are 16 elongated electrodes, and the alternating voltage is time-divisionally sequentially applied to each of the first electrodes 11.
Applied to. In this embodiment, the dot latent image density is 300 dots / in. Therefore, the time required to write 1 dot is
1 / (300 × 12 × 16) = 17.4 μs.

On the other hand, when the alternating voltage signal is applied between the first electrode 11 and the second electrode 12 and the dischargeable voltage is not reached at the same time, it takes a predetermined time Tr to rise as shown in FIG. Similarly, the fall also requires Tf. The rising time Tr is about 2 μs and the falling time Tf is about 8 μs. Therefore, the effective discharge time interval is 17.4-2.
-8 = 7.4 μs. Since the frequency of the alternating voltage is 3 MHz as described above, the peak of the alternating voltage in this 7.4 μs occurs 3 × 7.4 × 2 = 44 times if positive and negative are included. However, of the two peaks in one cycle, the first electrode 1
Discharge when 1 is a positive voltage with respect to the third electrode 13 does not contribute to latent image formation. FIG. 6 and FIG. 7 show the situation, in which the first electrode 11 is +10 with respect to the third electrode 13.
The electric lines of force at 00V (Fig. 6) and -1000V (Fig. 7) are shown. In the case of FIG. 6, it is understood that all the negative ions generated in the discharge generation portion are absorbed by the surface of the first dielectric substance 14 and are not in the downward direction. Therefore, the number of discharges that can be used to obtain one dot latent image is 44 /
2 = 22 times. In this way, by utilizing the discharge 10 times or more to form a 1-dot latent image, it is possible to obtain a dot-latent image with little size variation.

In order to make the number of ions generated 10 times or more per dot, the frequency f is Vp, the relative moving speed of the recording medium, n is the number of time divisions, and p is the number of dots formed per unit length of the recording medium.
When the time from the application of the amplitude of the alternating voltage to the generation of the effective ions is Tr and the time from the stop of the generation of the effective ions to the amplitude of the alternating voltage is Tf, 10 / [1 / (Vp × n × p) −Tr−Tf] ≦ f is satisfied.

In this embodiment, Vp = 12 in. / S, n = 16, p = 300
Dot / in. Since Tr = 2 μs and Tf = 8 μs, the frequency f satisfies f ≧ 1.4 MHz.
On the other hand, the generated ions are transferred from the ion generator to the third electrode 13
It took a certain amount of time to reach the opening 17, and it was found that the ions did not reach the opening 17 when an alternating voltage having a faster frequency was applied. It is considered that this is because the switching of the electric field between FIG. 6 and FIG. 7 is too early and the ions are not accelerated downward. Therefore, it is preferable that the frequency satisfies f ≦ 1 / T, where T is the time required for the ions generated near the second electrode 12 to reach the opening 17. Time T is about 0.2μs according to the experiment
Is. Therefore, in this embodiment, the frequency is 5 MH.
It is preferably z or less.

In this embodiment, since the frequency was set to 3 MHz, a uniform dot latent image was formed and a high-definition image was formed.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to form a uniform and high-definition latent image without variations in dot diameter.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrostatic recording head used in the electrostatic recording method of the present invention, FIG. 2 is an exploded perspective view of the electrostatic recording head of FIG. 1, and FIG. 3 shows a first electrode and a second electrode. FIG. 4 is a diagram showing a current flowing between the electrodes, FIG. 4 is a diagram in which currents between the first electrode and the second electrode are temporally overlapped, and FIG. 5 is an alternating voltage generated between the first electrode and the second electrode. FIG. 6 and FIG. 7 are diagrams showing the state of electric lines of force in different states in the apparatus of FIG. DESCRIPTION OF SYMBOLS 11: 1st electrode 12: 2nd electrode 13: 3rd electrode 14: 1st dielectric

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Takeuchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hideki Egami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Akito Hosaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. A plurality of first electrodes extending in a first direction, a second electrode extending in a second direction different from the first direction and forming a matrix with the first electrode, and a second electrode. On the other hand, a third electrode provided on the opposite side of the first electrode and having an opening corresponding to the matrix, the first electrode and the second electrode.
A first dielectric between the electrodes and a second dielectric between the second and third electrodes, the second dielectric having openings corresponding to the matrix, Alternating voltage is applied between the first electrode and the second electrode, ions are generated by the discharge between the second electrode and the first dielectric surface, and the ions are generated by the second electrode.
An electrostatic recording method of forming a charge pattern of charge dots on a surface of a recording medium by extracting the ions from an opening of the third electrode by a potential difference between the electrode and the third electrode,
An electrostatic recording method characterized in that the number of generation of effective ions when forming one charge dot is 10 or more. 2. The electrostatic recording method according to claim 1, wherein the relative moving speed of the recording medium is Vp, the number of time divisions is n, and the number of dots formed per unit length of the recording medium is p. ,
Let Tr be the time from the application of the amplitude of the alternating voltage to the generation of the effective ions, and Tf be the time from the stop of the generation of the effective ions to the amplitude of the alternating voltage being 0.
The frequency of the alternating voltage is 10 / [1 / (Vp × n × p) −
Tr-Tf] or more.