JPS59224371A - Electrostatic recording head - Google Patents

Abstract

PURPOSE:To increase the time constant of attenuation of a potential difference impressed on a gap, by a method wherein a groove cut to a predetermined depth from a head surface is provided in a predetermined width in the periphery of a multi-needle electrode, inclusive, and an insulating layer is provided on the entire region of the head surface exclusive of the groove. CONSTITUTION:The multi-needle electrode 3 and a controlling electrode are surrounded by a molded resin body 6 constituting a supporting member, the entire region of the electrode surfaces is finished by polishing, and a coating material based on fluorine is applied onto the entire region of the head surface in a thickness of 2mum as an insulating layer, and is hardened at normal temperature. Then, the groove is formed beneath the electrode 3 to constitute a gap part 12. Since the gap part is constituted of the groove 12 and an arbitrary height is obtained, it is unnecessitated to provide a spacer with a large thickness, and the insulating layer 11 can be provided with an arbitrary thickness. Accordingly, the composite capacitance of the insulating layer 11 and a dielectric layer beneath the controlling electrode 4 can be set high.

Description

[Detailed Description of the Invention] [Technical Field] The present invention provides an electrostatic capacitor in which the decay time constant of the potential difference applied to the gap provided on the main electrodeposition surface is increased in order to prevent a decrease in the recording rate, etc. Records - Regarding Rad.

[Prior art]

For conventional electrostatic recording, for example, as shown in Figure 1, a large number of kel wires are arranged in a row, and a voltage is applied to them according to the recorded information, and the tip of the wire is connected to the recording medium. 1 (for example, a dielectric belt, a drum, etc.) with an air gap 2 for corona discharge. control electrodes 4 which are arranged at a predetermined distance from each other and to which a predetermined bias voltage (having the opposite polarity to the voltage applied to the multi-needle electrode 3) is applied; and a control electrode 40 that leaves the air gap 2. A spacer 5 provided on the surface and a resin mold 6 for fixing each electrode are formed.

In the above configuration, a voltage (for example, -300V) is applied to the multi-needle electrode 3 in accordance with the recorded information on a line-by-row basis, while the control electrode 4 has a voltage polarity opposite to that applied to the multi-needle electrode 3. A voltage (eg, +350V) is applied. Usually, to simplify the drive circuit, electrodes are grouped and voltage is applied at predetermined timings. When the recording information is applied, the button activates the voltage and control of the multi-needle electrode 3 in the air gap 2 [ai4
A voltage proportional to the sum of the voltages (750V) is applied,
A discharge occurs on the recording medium, and the area immediately below the charged electrode in the multi-needle electrode 3 is charged, and an electrostatic latent image is formed.

An example of a recording device using such an electrostatic recording head is shown in FIG. 34 and a dielectric layer 35 provided on the surface of the recording body bell) 21, and an electrostatic recording body in which a spacer 5 is disposed so as to be able to come into contact with the surface of the recording body bell) 210. head 10 (shown in FIG. 1) and recording medium bell) 2
1, a motor 23 that drives the roller 22, a developing device 24 that attaches toner according to the surface charge to the surface of the recording belt 2J, and a roller 22 that drives the recording belt 21.
a transfer corotron 26 for adhering (transferring) toner adhering to the surface of the recording paper (wr paper passing) 25; a cleaner 27 for removing the toner adhering to the surface of the bell) 21 after the transfer is completed; an erase corotron 28 disposed upstream of the recording belt 27 and for removing electric charge from the recording belt 21;
A fixing device 29 that fixes the print or image transferred to the recording paper 25, a recording belt that is sent to the electrostatic recording head IO,
21; a drive circuit 31 that applies a recording voltage to the multi-needle electrode 3 and a bias voltage to the control electrode 4; The control unit 32 is configured to control the motor 23 to be driven.

In FIG. 2h, when a recording voltage is applied to the multi-needle electrode 3 of the electrostatic recording head io by the drive circuit 31 in response to a recording signal, the motor 23 driven by the control unit 32 is activated by the precharged dielectric As the body belt 21 rotates, an electrostatic latent image is formed on the surface. The toner is developed by the latent image developer 24 and transferred to the recording paper 25 by the transfer corotron 26. The transferred toner image is fixed by a fixing device 29 to obtain a recorded image. On the other hand, residual toner is removed from the recording belt 21 by a cleaner 27, and before that, the latent image is erased by an Irene corotron 28.

Note that when a pulse voltage as shown in FIG. 4 is applied to the multi-needle electrode 3 and the control electrode 4, each electrode and the recording belt 2
The equivalent circuit formed between 1 and 1 is as shown in FIG.

In FIG. 5, CI is the capacitance formed by the air gap 2, Cm e C4 is the capacitance caused by the dielectric layer 35 of the recording belt 21, and cs is the capacitance formed by the spacer 5.
The capacitance is shown in each figure. Further, R indicates the resistance due to the resistance layer 34. Furthermore, Pl indicates the potential directly under the control electrode of the resistive layer 34, p indicates the potential immediately below the multi-sided electrode, and Pa indicates the potential directly below the multi-needle electrode on the surface of the dielectric layer 35. In this way, each electrode and the resistance layer 340 are coupled through capacitance.

As described above, in the electrostatic recording head shown in Fig. 1, the recording medium surface is a smooth surface with excellent cleaning properties, so the spacer is formed of T, -, @ resin with good lubricity. In some cases, it is possible to prevent residual toner from adhering to the multi-needle electrode.

However, in conventional electrostatic recording heads, the attenuation constant becomes small due to the reasons detailed below, which results in insufficient recording discharge, which may result in a decrease in recording density or recording omissions. .

That is, when a pulse voltage Vc is applied to the control electrode 4 as shown in FIG. 4, the potential P of the resistance layer 34 immediately below it and the resistance layer potential P2 immediately below the multi-needle electrode have a differential waveform as shown in FIG. and decays exponentially, but the decay time constant is C8
Since it is determined by the product of the combined capacitance of C4 and the resistance R to the ground of resistor @34, if the spacer is thick, C
3 becomes smaller, the combined capacitance with No. C also becomes smaller, and the decay time constant becomes longer.

On the other hand, the surface potential P of the dielectric layer directly under the multi-needle electrode is Pi(
-Pa) It becomes a small similar waveform, but the potential difference across the gap becomes Pl-(-Vm), so p, lP
If the attenuation of g becomes faster, the air gap potential difference attenuates faster, and a sufficient recording discharge cannot be generated.

[Object and structure of the invention]

The present invention has been made in view of the above, and in order to increase the attenuation time constant of the potential difference applied to the air gap and ensure a sufficient discharge recording time, a multi-needle electrode is included and grooves are formed around the electrode.
The present invention provides an electrostatic recording head in which the entire surface of the head except for the grooves is coated with a thin insulating layer to form a gap.

〔Example〕

Hereinafter, the steps for electrostatic recording according to the present invention will be explained in detail.

FIG. 6 shows an embodiment of the present invention, and parts that are the same as those shown in FIG. The structure differs from the structure shown in FIG. 1 in that the groove 12 into which the insulating layer 11 is inserted is formed after coating with an extremely thin insulating layer 11.

Here, a specific example of each member constituting the head is as follows.

Main electrode (multi-needle electrode 3)...5Q, pφ nickel wire, 12 wires/-1257W width, control electrode 4...phosphor bronze, 1 corresponding to 64 main electrodes
Pair, 4.8 x 4.8 tone square 1 with 5.33 tone pitch, Holding member (resin mold 6)...Epoxy resin, each electrode is molded by the holding member with the above dimensions and materials, and the electrode surface The entire head surface is polished and finished, and a fluorine-based material (PTFF: mainly made of tetrafluoroethylene, cellulose binder, solvent, etc.) is applied as an insulating layer 11 to the entire head surface.
Coat it to a thickness of 2pn and leave it at room temperature for 2 hours to harden.

Then, a groove 12 is formed directly under the multi-needle electrode 3.

This groove 12 is formed by a disc-shaped rubber grindstone (as shown in FIG. 7).
It has a hardness of 90° and is made of silicon carbide abrasive grains and a silicone binder (the dimensions shown in the figure) and is formed into the dimensions shown in FIG.

In other words, the grooves 12 of the grooves become voids. Note that since the rubber grindstone has an acute edge, its cross section is formed into a trapezoid.

In the above configuration, the void portion is formed by the groove 12 and can be made to any height, so there is no need to give the Nubesa a thickness unlike the conventional one, and the insulating layer 11 can be made to have any thickness. If the thickness is 2 μm as described above, the combined capacitance of the insulating layer 11 and the dielectric layer directly under the control electrode 4 can be increased, and the attenuation constant of the potential difference applied to the gap can be increased, so that sufficient discharge can be achieved. Recording time can be secured.

When the recording head of the present invention shown in FIG. 6 was applied to the recording apparatus shown in FIG. 2, the following results were obtained.

Multi-needle electrode...-300V applied for 20μS, control electrode/
...+350V't-20/js applied, recording belt moving speed...100mm/sea.

Development: Two-component magnetic brush method, Transfer: Corotron transfer, Cleaner: Doctor blade, Fixing: Heat roll. When I tried to print on A4 recording paper under the above conditions, the results were as follows. I got a good record as shown in the table.

9(a) to (d) show a modification of the present invention, in which the order of forming the groove and the insulating layer is reversed. That is, as shown in FIG. 9(a), After forming a groove 12 with a grindstone, the inside of the groove 12 is masked with a masking member 13 as shown in FIG. 9(b), and the surface is made flat, and then as shown in FIG. 9(c). Insulating layer 1 is applied to the entire head surface.
A gap can be formed by coating the masking member 13 with a thickness of 2 pm and then removing the masking member 13 together with the insulating layer 11 immediately below as shown in FIG. 9(d). According to this embodiment, the same effect as the embodiment shown in FIG. 6 can be obtained.

(Moving bed of the invention) As explained above, according to the electrostatic recording head of the present invention,
Since the gap is made into a groove and the insulating layer is made extremely thin to increase the capacitance directly under the control electrode, the decay time constant of the potential difference applied to the gap can be increased, and a sufficient discharge time can be ensured.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional electrostatic recording head, and FIG. 2 is a groove diagram showing an example of a recording device using an electrostatic recording head.
FIG. 3 is a cross-sectional view of the recording body formed on the surface of the recording body bell) 210 shown in FIG. 2, and FIG. 4 is a cross-sectional view of each electrode of the electrostatic recording head shown in FIG. Figure 8155 is an equivalent circuit diagram of an electric circuit formed in the recording medium and the insulating layer of the electrostatic recording head, Figure 6 is a sectional view showing an embodiment of the present invention, Figure H7 is a voltage waveform diagram showing the potential. FIG. 6 is a front view of a grindstone used in the manufacturing process of the head, FIG. 8 is an explanatory diagram showing an example of the dimensioning of the groove 12 according to the present invention, and FIG.
), (b), (C), and (d) are explanatory diagrams showing manufacturing processes of modified examples of the present invention. Explanation of symbols 3...Multi-needle electrode, 4...Control electrode, 6...Resin mold, 11...Insulating layer, 12...Groove, 13...Masking member.

Claims (1)

[Claims] A multi-needle electrode in which a large number of needle electrodes are arranged in a row to apply a voltage according to recorded information, and a predetermined bias voltage arranged in parallel to the multi-needle electrode. In an electrostatic recording head in which a control electrode to which is applied is molded with resin or the like [7], a groove is carved at a predetermined depth from the head surface over a predetermined width around the multi-needle electrode, and a groove excluding the groove is formed. An electrostatic recording head characterized by an insulating layer provided over the entire head surface.