US3576585A

US3576585A - Scanning and recording device for electrostatic recording

Info

Publication number: US3576585A
Application number: US770318A
Authority: US
Inventors: Masaru Ohno; Kimitaro Suzuki
Original assignee: TOHO DENKI CO Ltd
Current assignee: TOHO DENKI CO Ltd
Priority date: 1968-10-24
Filing date: 1968-10-24
Publication date: 1971-04-27
Anticipated expiration: 1988-04-27

Abstract

A scanning and recording device for electrostatic recording which comprises a dielectric sheet sandwiched between two electroconductive sheets, one of said conductive sheets being photoetched into the form of the multistylus, the other conductive sheet being used as a ground electrode, one of the end portions of said sandwiched sheets being made into a cylindrical shape to be used as the scanning head, and the flat and straight end surface at the other end of said sheets being used as the recording head, said device being suitable for an operation at a high scanning rate without necessitating any special electronic tube as recording element.

Description

Inventors Masaru Ohno;

Kimitaro Suzuki, Tokyo, Japan 770,318

Oct. 24, 1968 Apr. 27, 1971 Toho Denki Co., Ltd.

Tokyo, Japan Appl. No. Filed Patented Assignee SCANNING AND RECORDING DEVICE FOR ELECTROSTATIC RECORDING 6 Claims, 10 Drawing Figs.

3,307,198 2/1967 Morgan 346/74 Re26,212 5/1967 Johnson et al. 346/74 3,380,070 4/ I 968 Betts et al.. 346/74 Primary Examiner-Bernard Konick Assistant ExaminerGary M. Hoffman Attorney-lecies and Greenside ABSTRACT: A scanning and recording device for electrostatic recording which comprises a dielectric sheet sandwiched'between two electroconductive sheets, one of said conductive sheets being photoetched into the form of the multistylus, the other conductive sheet being used as a ground electrode, one of the end portions of said sandwiched sheets being made into a cylindrical shape to be used as the scanning head;and the flat and straight end surface at the other end of said sheets being used as the recording head, said device being suitable for an operation at a high scanning rate without necessitating any special electronic tube as recording element.

PAIEII EII mm 197i 3576.585

SHEU 1 BF 2 FIG, 2

I I I I I I I I I I I 'IIIIIIIIIIIIIIIIIIII/Ill 22 FIG. 4

7 2 23 FIG. 5 l PRIOR ART T TC T 1 INVENTOR Masaru Ohno and Kimitaro Suzuki By Their Attorneys ATTORNEY PATENTED APRZTIQYI SHEET 2 BF 2 FIG. 6 PRIOR ART SLB-SCANNING AIN SCANNING FIG. a

nun u nun u on. N on 28 noun anon on INVENTOR Masaru Ohno and mitaro Suzuki nv fl wfkw heir Attorneys ATTORNEY SCANNING AND RECORDING DEVICE FOR ELECTROSTATIC RECORDING BACKGROUND OF THE INVENTION I. Field of the Invention Thisinvention relates to a scanning and recording device for electrostatic recording in a facsimile system, particularly to such a device utilizing a multistylus electrode.

2. Description of the Prior Art Generally speaking, the recording process with an electrostatic. recording system comprises the steps of, causing a recording stylus to .contact the surface of an electrostatic recording paper which is coated with an insulating resin or the like, applying a signal voltage of several hundred volts to said recording stylus thereby to produce a latent image of electrification corresponding to said signal voltage on said insulating layer of resin, and developing and fixing said latent image to obtain a visible recording. Such a process with which an electrostatic latent image is directly produced by electrical means, requires a comparatively high voltage but little recording current. Therefore, such a recordingsystem is economical in power consumption, suitable for high-speed recording and produces a distinct record of good contrast on white paper.

In one'conventional electrostatic recording system, it is a common practice to adopt a planar scanning system, as it is convenient to continuously advance the recording paper for the developing and fixing process after the electrostatic latent image has been produced. Typical examples of the conventional electrostatic recording systems will be described hereunder.

Endless belt-type scanner comprises a plurality of metallic styluses planted at uniform spaces on an endless belt extended between a pair of pulleys, the recording being performed by imposing the signal voltage on said styluses which scan a dielectric recording paper in contact with said paper. This system is not advantageous in regard to the following points that it is not suitable for high-speed scanning, that the reproduced picture is deteriorated by the frictional electrification as the styluses are run in contact with therecording paper, and that it is short in service life because of damage to the belt and other components.

Other conventional electrostatic recording systems include planar scanning systems in which the ends in one side of a number of insulated conductors are aligned uniformly to form a multistylus electrostatic recording head and the other ends are connected to a signal distributor which comprises terminals disposed in a circle and a rotatingwiper, and with which the electrostatic recording is performed on a recording paper which moves adjacent to the recording head, the image signal introduced through said signal distributor being led to said styluses in the recording head. A great disadvantage of this system is that it is not simple nor easy to construct.

A further example of the conventional scanning systems is the electrostatic recording tube which is a cathode ray tube whose faceplate is provided with an array of a number of styluses penetrating therethrough, said array of styluses being scanned at their inner ends with the electron beam whose intensity varies in, correspondence with the image signal voltage, and thus the electrostatic recording being made on a recording paper which is passed adjacent tothe faceplate. Though this known system is suitable for high-speed scanning, it has a great disadvantage in regard to the following points that such an electrostatic recording tube is difficult to fabricate and very high in cost.

SUMMARY OF THE INVENTION An object of this invention is to provide a scanning and recording device for electrostatic recording comprising two electroconductive sheets attached to both surfaces of a dielecformed in one of the end portions of said sandwiched sheets, and a cylindrical scanningportion formed in the other end portion of said sandwiched sheets.

Another object of this invention is to provide a scanning and recording device for electrostatic recording wherein said electrostatic recording head in said one end is inclined against the recording paper in order to increase the area of the end of a stylus in contact with the recording paper.

This invention has eliminated the previously mentioned disadvantages of the conventional systems, and has made it possible to effect a high-speed scanning with a simple structure. Further, according to this invention, an increased density of recording is obtained, as the shape of an elementary dot of record which was conventionally a circle is made an ellipse thereby to fill more area in the space between subscannings or two rows of main scanning.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric view of sandwiched sheets used in this invention;

FIG. 2 is a side view of the sandwiched sheets shown in FIG.

FIG. 3 is an isometric view of an embodiment of the scanning and recording device of this invention;

- FIG. 4 shows an equivalent circuit of the capacitance between conductors of the sandwiched sheets;

FIG. 5 is a schematic diagram illustrating a conventional scanning system;

FIG. 6 is an example of a record made by the conventional system shown in FIG. 5;

FIG. 7 is a schematic diagram illustrating the scanning and recording device of this invention in use;

FIG. 8 is an example of a record made by the device shown in-FIG. 7;

FIG. 9a is an isometric view of another embodiment of the scanning and recording device of this invention; and

FIG. 9b is an enlarged view of a portion of the device shown in FIG. 90.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A scanning and recording device of this invention comprises a sandwiched formation including two electroconductive sheets attached to both surfaces of a dielectric sheet, one of the electroconductive sheets being photoetched to form a multistylus and the other of the electroconductive sheets being used as a ground electrode.

Referring to FIGS. I and 2, the multistylus 2 is seen to be provided on one surface of the dielectric sheet 1 and the ground electrode 3 on the other surface. One end portion of the above-described sandwiched sheets is formed into a cylinder to be used as a part of the scanner or distributor, while the other end portion is maintained flat and straight and is solidified with a synthetic resin or the like to be formed into a recording head 4. In this embodiment, the above-mentioned cylindrical portion is formed with the multistyluses 2 outside and the ground electrode 3 inside. As shown in FIG. 3, a pair of brushes 6 and 7 are provided in contact with said cylindrical portion and a high voltage corresponding to image signal is applied to said brush 6 while said brush is rotated around the cylindrical portion. Thus, on the other end of the device, an

electrostatic image isobtained through the recording head 4 on a recording paper 5 which is moved in the direction perpendicular to the lengthwise direction of the recording head. The thus obtained electrostatic latent image is turned to a visible image through development with a toner.

In FIG. 4 which shows an equivalent circuit of the capacitance between conductors, each

conductor

2,, 2 2 leading to each stylus is seen on one surface of the dielectric sheet 1. In operation, when a signal voltage is applied to a stylus or conductor through the brush 6, a voltage is induced in the adjacent conductors owing to the static capacitancesC C 2, between the conductors. The charge distribution due to the leakage of the image signal voltage to adjacent conductors' remarkably lowers the resolution of the picture in the direction of the main scanning. To prevent the above-mentioned deterioration of the resolution, the around electrode 3 is provided opposite to the conductors of the multistylus.

I Thus, the effects of the static capacitances C C between adjacent conductors are reduced by the capacitances C', C", C', between respective conductors and the ground. For example, assuming that a signal voltage V is applied to the stylus or conductor 2, through the brush 6, voltage V, induced in the

adjacent conductor

2, or 2;, is divided between C and C, or between C, and C' as shown by the following formula:

, 14 a cushion for urging the recording paper 13 against the stylus 11', 15 a scanner, and 16 an amplifier. In this arrangement, if a voltage related to the input signal is applied to the conduc tor or stylus 11, the recording paper is electrified at the spot where said stylus is in contact with the paper, thus a latent image being made on the paper. This latent image is turned to a visible image as shown in FIG. 6 through the development. In FIG. 6, a visible image 18 is seen on the recording paper 13. Electrification of the recording paper and amount of the toner deposited on the latent image vary depending on charac teristics of the recording paper and the developing agent, and the density of the record is limited. Assuming that the space between adjacent styluses is a and the space of the subscanning is b as shown in FIG. 6, it is required for obtaining a satisfactory apparent density to reduce the spaces a and b as much as possible. In a high-speed recording with low density scanning, the space b is inevitably coarse resulting in low apparent density. According to this invention, the recording head 22 is positioned in such a manner that the multistylus 21 is inclined against the recording paper 23 at an angle as shown in FIG. 7. In FIG. 7, reference numeral 24 indicates a cushion for urging the recording paper 23 against the stylus 21, numeral 25 the ground electrode, 26 a scanner, and 27 an amplifier. In this arrangement, if a voltage related to the input signal is applied to the stylus 21, the recording paper is electrified at the spot where said stylus is in contact with the paper, thus a latent image being made on the paper. This latent image is turned to a visible image as shown in FIG. 8 through the development. In FIG. 8, a visible image 28 is seen on the recording paper 23. An elementary dot of the image has the shape of an ellipse in FIG. 8, whereas it is a circle in FIG. 6. The length of the long axis of the ellipse is determined by the angle 0, and so is the space C between adjacent dots in the direction of the subscanning. Effects of this arrangement will be further explained hereunder.

Assuming that the multistylus included m/mm elementary styluses, the diameter of each stylus being 7 mm and that the rate of subscanning is F-lines/mm, the conventional system as shown in FIG. 5 will produce a record in which the center distance b between adjacent dots in the direction of subscanning is HF and the space between dots in the same direction is HP 7. According to this invention, each of the elementary dots of the record assumes the shape of an ellipse as shown in FIG. 8 owing to the inclination of the stylus by the angle 6, thus the length of the long axis of the ellipse being 'y/cos 0 and the space 0' between adjacent lines being l/F-*y /cos 0. As y/cos 0 is larger than y in the range of 0 0 90, the space C in FIG. Bis smaller than the space C in FIG. 6. Thus, the apparent density of the image in the direction of the subscanning is improved.

FIGS. 9a and 9b show another embodiment of the scanning and recording device of this invention. In this embodiment, the cylindrical end portion of the device is formed with the multistylus 102 inside and the ground electrode 103 outside, contrary to the embodiment shown in FIG. 3. The dielectric sheet is indicated by numeral 101 in the FIG. Scanning is performed by applying a high voltage corresponding to an image signal to the brush 106 while said brush is rotated inside the cylindrical portion. Thus, on the other end of the device, an electrostatic latent image is obtained through the recording head 104 on a recording paper which is moved in the direction of the subscanning. Another brush l07'which is grounded is rotated with the brush 106 but a bit behind it to eliminate the residual electricity. In this embodiment too, the feature of the inclined stylus as shown in FIG. 7 may be included in order to improve the recording density.

We claim:

1. A scanning and recording device for electrostatic recording, comprising a pair of electroconductive sheets each of which is substantially planar, a dielectric sheet disposed between and substantially coextensive with said electroconductive sheets to form a sandwich therewith, one of said electroconductive sheets being photoetched to provide raised portions comprising styluses the other of said electroconductive sheets being adapted to serve as a ground electrode, one end of said sandwich being formed in the shape of a cylinder and adapted to serve as a scanner, the other end of said sandwich presenting a substantially planar recording head, and the said dielectric sheet being of substantial thickness relative to the distances between said styluses so as to thereby reduce the static capacitance between said styluses and thus improve resolution of the recorded picture.

2. A scanning and recording device as defined in claim 1, wherein said styluses are inclined against the recording paper at a certain angle.

3. A scanning and recording device as defined in claim 1, wherein said cylindrical portion is formed with said styluses on the outside of the cylinder.

4. A scanning and recording device as defined in claim 3, wherein said styluses are inclined against the recording paper at a certain angle.

5. A scanning and recording device as defined in claim 1, wherein said cylindrical portion is formed with said styluses on the inside of the cylinder.

'6. A scanning and recording device as defined in claim 5, wherein said styluses are inclined against the recording paper at a certain angle.

Claims

6. A scanning and recording device as defined in claim 5, wherein said styluses are inclined against the recording paper at a certain angle.