JPH0665496B2 - Electrostatic recording method and head - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrostatic recording method and an electrostatic recording head for forming an electrostatic latent image on a recording material capable of holding a charge.

BACKGROUND ART As a conventional electrostatic recording method, a direct discharge recording method in which a needle electrode is used to directly perform a discharge between a charge holding member and an electrode, and a discharge is performed at a position distant from the charge holding member, which is generated There is an indirect discharge recording method using ions, but in the direct discharge recording method, the charge holding member surface is easily damaged by the contact between the needle electrode and the charge holding member surface, or the needle electrode and charge holding member surface It has drawbacks such as the need to keep the interval with high accuracy.

On the other hand, in the indirect discharge recording method, the distance between the needle electrode and the charge holding member surface can be greatly widened as compared with the case of the direct discharge recording method, so that the accuracy is gentle. Since stable discharge can be performed at a position distant from, and the ions generated thereby can be attached to the surface of the charge holding member, it is easy to use, and therefore various recording electrodes that can be used in the apparatus of this system have been proposed.

For example, US Pat. Nos. 4,155,093 and 4,160.
No. 257 proposes an electrode as an indirect discharge recording method. This is because two electrodes are provided across the dielectric, an alternating voltage is applied to the electrodes, and one of the two polar ions generated by the discharge between the electrode and the dielectric surface through the air gap. Are accelerated to form an ion flow, which is then guided to the charge holding member. Since the discharge in this case is performed through the dielectric, a large current does not flow and the electrodes are less damaged. However, since the discharge occurs between the electrode and the dielectric, destruction of high-energy electrons on the dielectric surface due to discharge and chemical deterioration due to ozone, etc. are severe, and the risk of dielectric breakdown eventually arises. There was such a problem.

OBJECT OF THE INVENTION It is an object of the present invention to provide an electrostatic recording method and an electrostatic recording head in which the above-mentioned drawbacks of the prior art are eliminated and electrodes are less likely to corrode.

According to the present invention, a dielectric is sandwiched between an excitation electrode and a first discharge electrode, and an end of a second discharge electrode is provided at an end of the first discharge electrode with a gap. In an electrostatic recording method in which an alternating voltage is applied between the excitation electrode and the second discharge electrode to attach ions to a recording member, the excitation electrode does not extend to a position facing the gap. An electrostatic recording method is provided, wherein the first and second discharge electrodes are electrically insulated from each other, and the ions are generated by a discharge between the first and second discharge electrodes, and a static recording method suitable for this method. Since the electric recording head is provided, the corrosion and wear of the electrodes are reduced, and the problem of dielectric breakdown due to the deterioration of the dielectric is solved.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of one element of an electrostatic recording head 1 according to an embodiment of the present invention. As will be described later, actually, a plurality of these elements are provided, but for simplification of description, one will be described first. The electrostatic recording head 1 includes a dielectric 2, a discharge electrode 3,
It has an excitation electrode 4 and an insulating layer 5. The dielectric 2 is made of an inorganic material such as ceramic, mica, or glass, or an organic polymer material such as polyimide, Teflon, polyester, or polyamide, and is sandwiched by the excitation electrode 4 and the discharge electrode 3 as shown in the figure. Two discharge electrodes 3 are provided, and a gap (air gap) exists between them.
The excitation electrode 4 is provided so as not to extend to a position facing the void. The material of the discharge electrode 3 is a conductive material having a thickness of 1 to 100 μm, such as nickel, tungsten, titanium, stainless steel, gold or nickel-plated copper. Two excitation electrodes 4 are also provided, which are insulated from each other by an insulating layer. As the material of the excitation electrode 4, the above conductive material is used similarly to the material of the discharge electrode 3. The insulating layer has a function of preventing discharge between the two excitation electrodes 4, and the material may be any one having an insulating property, for example, an inorganic or organic polymer material similar to that used for the dielectric 2 above. Is suitable, and it is also possible to use the same material for the dielectric layer 2 and the insulating layer 5. The excitation electrode 4 is connected to the excitation voltage power supply 6. The excitation voltage power supply 6 is a single or multiple pulse wave or sine wave,
It is an alternating voltage such as a triangular wave or a rectangular wave.

In operation, an excitation voltage is applied between both excitation electrodes 4 by an excitation voltage power supply 6. Thereby, the dielectric 2
When electric charges of opposite polarities are induced on the respective discharge electrodes 3 side via an electric field and an electric field of a certain level or more is formed in the gaps between the discharge electrodes 3, spark discharge occurs between these discharge electrodes 3. Then, positive and negative ions are formed.

Here, in order to explain this phenomenon, the electrostatic recording head 1
The equivalent circuit of is shown in FIG. The electric capacity between the excitation electrode 4 and the discharge electrode 3 via the dielectric 2 corresponds to the capacitor 9a of this equivalent circuit. The capacitance of the gap between both discharge electrodes 3 corresponds to the capacitor 9b of the equivalent circuit, and the column 9c of Zener diodes connected in parallel to this capacitance.
Corresponds to the spark discharge starting voltage V between the voids (the Zener voltage is almost equal to the spark discharge starting voltage V). The excitation voltage is shown at 6 as in FIG. When an excitation voltage is applied to this equivalent circuit and the voltage across the capacitor 9b corresponding to the air gap becomes equal to or higher than the Zener voltage, a current flows to the Zener diode side. This corresponds to the flow of the discharge current in FIG. 1 and the generation of ions. The current at this time changes depending on the amount of charge charged in the capacitor 9a, and thus the capacitance thereof. Therefore, even in an actual circuit, the discharge current can be controlled by changing the thickness, the dielectric constant or the area of the dielectric 2. That is, since the discharge current flowing between the discharge electrodes is limited by the amount of charge stored in the capacitor between the excitation electrode and the discharge electrode, there is a problem of electrode consumption due to a large current accompanying a spark discharge as seen in a conventional recording head. There is no.

The gap between the discharge electrodes 3 is 1 μm to 1 mm, but 1 μm to 50 μm is preferable in order to lower the discharge start voltage.

In this configuration, since the discharge is generated between the discharge electrodes 3, the influence on the dielectric is smaller than that of the conventional one. That is, in the conventional electrostatic recording head 1, for example, the head disclosed in U.S. Pat. No. 4,155,093, discharge is generated between two electrodes that sandwich the dielectric, and therefore durability due to tree breakdown of the dielectric is caused. However, according to this configuration, the consumption of the electrodes is minimized, the problem of dielectric breakdown due to the deterioration of the dielectric is solved, and the durability is improved.

FIG. 3 shows a method for performing electrostatic recording on the charge holding member 7a using the electrostatic recording head 1 of this embodiment. Ions generated at the above-mentioned discharge electrode 3 are extracted toward the charge holding member 7a by an external electric field. For this reason, a bias voltage is applied between the discharge electrode 3 and the ground counter electrode 7b provided on the back surface of the charge holding member 7a by the bias voltage applying power source 8. In the present embodiment, this bias voltage is the discharge electrode. 3 is provided to only one of the discharge electrodes 3, and the other discharge electrode 3 is in an electrically floating state. In this embodiment, the counter electrode 7b
On the other hand, since a positive voltage is applied to the discharge electrode 3 side, only positive ions are extracted and attached on the charge holding member 7a. This attached ion corresponds to one dot of recording. The charge holding member 7a moves in the direction of the arrow.

The distance between the discharge electrode 3 and the charge holding member 7a is 10 μm to 1
mm, preferably 10 μm to 200 μm.

FIG. 4 shows another embodiment of the present invention. Members corresponding to those in FIG. 1 are designated by the same reference numerals. The difference from the embodiment of FIG. 1 is that the excitation electrode 4 is provided only in the portion facing the discharge electrode 3 on one side, and the excitation electrode 4 is not provided on the other side. Then, the excitation electrode 4 is directly connected to the discharge electrode 3 on the other side via the excitation voltage power supply 6.

An equivalent circuit of this configuration is shown in FIG.

The electric capacity between the excitation electrode 4 and the discharge electrode 3 via the dielectric 2 corresponds to the capacitor 9a of this equivalent circuit. The capacitance of the gap between the discharge electrodes 3 corresponds to the capacitor 9b of the equivalent circuit, and the Zener diode array 9c connected in parallel to this capacitance corresponds to the spark discharge start voltage V between the gaps (the Zener voltage is It is almost equal to the spark discharge starting voltage V). The excitation voltage is shown at 6 as in FIG.

As can be understood from this equivalent circuit, the present embodiment is similar to the above-described embodiment, but as is clear from comparison with FIG. 2, the electrical characteristics of the capacitor 9a, that is, the dielectric 2 is shown. There is one less capacitive component, and the excitation voltage is lower in the configuration of FIG. 4 in order to obtain the same discharge state. Of course, the spark discharge starting voltage is the same.

FIG. 6 shows a method of performing electrostatic recording on the charge holding member 7a using the electrostatic recording head 1 of this embodiment. Ions generated at the above-mentioned discharge electrode 3 are extracted toward the charge holding member 7a by an external electric field. For this reason, a bias voltage is applied between the discharge electrode 3 and the ground counter electrode 7b provided on the back surface of the charge holding member 7a by the bias voltage applying power source 8. In the present embodiment, this bias voltage is the discharge electrode. 3 is applied to only one of the electrodes 3, that is, the one directly connected to the excitation electrode 4, and the other discharge electrode 3 is in an electrically floating state. This bias voltage is applied to the other discharge electrode 3
May be given only to. In this embodiment, since a positive voltage is applied to the discharge electrode 3 side with respect to the counter electrode 7b,
Only positive ions are extracted and attached on the charge holding member 7a. This attached ion corresponds to one dot of recording. The charge holding member 7a moves in the direction of the arrow.

FIG. 7 is a bottom view of the recording head of FIG. 1 viewed from the discharge electrode 3 side, showing a state in which a plurality of heads are arranged side by side on an array. The discharge electrode 3 has a thickness of 1 to 100 μm, and the dielectric 2 has a thickness of 1 μm to 1 mm. This electrode array can be manufactured with high density by an etching method or the like.

8 to 12 show a method of driving the recording head. 8th
FIG. A is an example of driving the recording head of FIG. 1, and FIG.
The figure shows an example of driving the recording head of FIG. In FIG. 8B, all the discharge electrodes 3 on one side are electrically connected and a bias voltage is applied thereto, and the excitation voltage synchronized with the recording signal is applied to each excitation electrode 4 corresponding to the discharge electrode 3 on the other side. Is applied.

FIG. 9 shows an example of driving the recording head of FIG. 4, in which a bias voltage is applied in a time division manner. In synchronization with this, the excitation voltage is applied. As a result, the number of excitation voltage power supplies 6 synchronized with the recording signal can be reduced. This driving method can also be applied to the case of FIG.

FIG. 10A shows an example of a method of driving the recording head of FIG. 1, in which the excitation electrode 4 is electrically connected and the bias voltage connected to each discharge electrode 3 is switched in synchronization with the recording signal. . This drive method is applied to the case of FIG. 4 and is shown in FIG. 10B.

In FIG. 11, the discharge electrodes 3 are arranged in a staggered arrangement, and the image density can be doubled. In the figure, the discharge electrode 3 in the center column is shared by the electrodes on both sides thereof. Except for this point, the driving method of this configuration is the same as in FIG. 10A.

FIG. 12 is a modification of FIG. 10B in which the excitation voltage side is time-division driven to reduce the number of bias voltage switching circuits.

According to the configurations of FIGS. 8 to 12, high density recording is possible, and the number of circuits can be easily reduced by driving the excitation voltage or the bias voltage or both in a time division manner. it can.

13 and 14 show an electrostatic recording head 1 according to another embodiment of the present invention, FIG. 13 is a sectional view, and FIG. 14 is a bottom view. Basically, the configuration for generating ions is the first
It is similar to the figure. Therefore, the members corresponding to those in FIG. 1 are designated by the same reference numerals. In this embodiment, in order to extract specific ions and form an electrostatic charge image on the charge holding member 7a, a screen electrode 11 that controls the ion flow is provided between the discharge electrode 3 and the charge holding member 7a. Then, the voltage Vs (screen voltage) having a polarity smaller than the absolute value of the bias voltage is applied to the screen electrode 11.
This screen voltage ensures control of the ion flow. Depending on whether the electric potential of the discharge electrode 3 is higher or lower than the electric potential of the screen electrode 11 in absolute value, the ion current of a specific polarity (positive polarity in this figure) is switched, and electrostatic recording is performed on the charge holding member 7a. Do. At this time, the outflow of ions of opposite polarity (negative polarity in this figure) is caused by the screen electrode 1.
The presence of 1 ensures blocking. Therefore, it is possible to reliably prevent the once formed electrostatic image from being neutralized and erased by the ions of the opposite polarity, and it is possible to form a higher-definition electrostatic image.

As shown in FIG. 14, the screen electrode 11 is an insulator 1.
2 is attached to the discharge electrode 3 at a constant interval, and the opening of the screen electrode 11 coincides with the discharge part of the discharge electrode 3.

Also in the electrostatic recording head 1 having the structure shown in FIG. 4, the screen electrode 11 can be added in the same manner, and the sectional view and the bottom view at that time are shown in FIGS. 15 to 16. In this case also, the same effect as above can be obtained.

The driving method when the screen electrode 11 is added is basically the same as that described with reference to FIGS.

EFFECTS OF THE INVENTION As described above, according to the present invention, the wear of electrodes is reduced, the problem of dielectric breakdown due to the deterioration of the dielectric is solved, and an electrostatic recording head with high durability and high recording density is provided. Provided.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrostatic recording head according to an embodiment of the present invention, FIG. 2 is an electrical equivalent circuit diagram of the electrostatic recording head of FIG. 1, and FIG. 3 is an electrostatic recording head of FIG. FIG. 4 is a sectional view showing a state of performing electrostatic recording, FIG. 4 is a sectional view of an electrostatic recording head according to another embodiment of the present invention, and FIG. 5 is an electrically equivalent circuit diagram of the electrostatic recording head of FIG. FIG. 6 is a sectional view showing a state in which electrostatic recording is performed by the electrostatic recording head of FIG. 4, and FIG. 7 is a view in which the electrostatic recording heads of FIG. 8A, 8B, 9, 10A, 10B, 11 and 12 show the arrangement and driving method of the electrostatic recording head, the bottom view seen from the discharge electrode side, and FIGS. 13 and 15 show the present invention. 14 is a sectional view of an electrostatic recording head according to still another embodiment of the present invention, FIG. 14 is FIG. 13 and FIG. The electrostatic recording head is a bottom view of the those arranged in an array from the discharge electrode side, respectively. DESCRIPTION OF SYMBOLS 2: Dielectric 4: Excitation electrode 3: Discharge electrode 6: Alternate voltage applying means

Claims (4)

[Claims] 1. An excitation electrode and a first discharge electrode are opposed to each other with a dielectric interposed therebetween, and an end portion of a second discharge electrode is provided at an end portion of the first discharge electrode with a gap therebetween. And the second
In the electrostatic recording method for applying ions to the recording member by applying an alternating voltage to the discharge electrode, the excitation electrode is provided so as not to extend to a position facing the gap, and The second discharge electrode is electrically insulated from each other, and the ions are generated by the discharge between the first and second discharge electrodes. 2. The first and second excitation electrodes and the first and second discharge electrodes are opposed to each other with a dielectric interposed therebetween, and the second discharge electrode is provided at an end of the first discharge electrode. Of the first and second excitation electrodes, the end portion of which is provided with a gap, and an alternating voltage is applied between the first and second excitation electrodes to attach ions to a recording member. Is provided so as not to extend to a position facing the gap, the first and second discharge electrodes are electrically insulated from each other, and the ions are generated by the discharge between the first and second discharge electrodes. An electrostatic recording method characterized by generating. 3. A dielectric, an excitation electrode provided on the first surface side of the dielectric, and a first discharge provided on the second surface side of the dielectric so as to face the excitation electrode. An electrode and a second discharge electrode having an end portion provided on the second surface side of the dielectric body with an end portion of the first discharge electrode and a gap, and the excitation electrode, In the electrostatic recording head in which an alternating voltage is applied between the second discharge electrode and the second discharge electrode, the excitation electrode is provided so as not to extend to a position facing the gap, and the first and second discharge electrodes are provided. Is an electrostatic recording head characterized by being electrically insulated from each other. 4. A dielectric, first and second excitation electrodes provided on the first surface side of the dielectric, and a second dielectric of the dielectric.
Provided on the surface side of the first electrode facing the first excitation electrode.
Of the discharge electrode and the first surface on the second surface side of the dielectric.
Second discharge electrode having an end portion provided at the end portion of the discharge electrode via a gap, and an alternating voltage is applied between the first and second excitation electrodes. In the head, the first and second excitation electrodes are provided so as not to extend to a position facing the gap, and the first and second excitation electrodes are provided.
The electrostatic recording head is characterized in that the discharge electrodes of are electrically insulated from each other.