DE1597850A1 - Process for developing an electrostatic latent image - Google Patents

Description

PATENT LAWYERS

DR. E. WIEGAND DIPL-ING. W. NIEMANN 1597850

DR. Ai KOHLER DIPL-ING. C GERNHARDT

MÖNCHEN HAMBURG

phone: 555 + 74 8000 MÖNCHEN 15.28 “December 1967

TELEGRAM CARPATENT NUSSBAUMSTSASSE 10

■ W. 13 48 ^ / 67 13 / Never

Fuji Shashin Movie Kabushiki Kaisha Kanagawa (Japan)

Process for developing an electrostatic latent image

The invention relates to a method for developing an electrostatic latent image, the Edge effect eliminated in the cascade development process

In the usual xerography, as for example in the U.S. Patents 2,297-69.1 or 2,357,809 sine zero graphic plate *. -which consists of an electrically ■ conductive. Base plate and an electrical conductive » iUhigen insulating layer, uniformly electrically charged and accordingly an "em su reproducing original after the"

0ÖÖ83Ä / UIi

Projection method! Exposed. Be through the exposure the uniform charges on the photoelectrically conductive insulating layer according to the intensity of the Discharge of light, causing "the formation of a latent electrostatic Image on it leads. The electrostatic latent image is developed using a cascade developer, that of a granular material called carrier and a pigmented material called toner Powder, which adheres to the carrier surface, consists, with the toner -, in surface contact with the photoelectrically conductive insulating layer and placed on it accordingly the latent electrostatic scrolling cie]? lititelectric conductive insulating layer. Typically, in practice, the developed image has been transferred onto a support or transfer material and fixed in a suitable manner »The surface contact of a toner with a conductive one Insulating layer was carried out by a method that was known as the cascade process, wherein a toner carrying granular material, hereinafter referred to as a cascade developer, cascade to the photoelectrically conductive insulating layer is performed. This development process leads to a good ji result - especially with ^ (printed matter or letters) or linear pictures on a white background as originals -

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In the case of an original image with a large area, however, the so-called edge defect occurs, i.e. the The state of the electric field in the zone of a latent electrostatic image agrees with the charge density, which forms the electrostatic latent image do not match to such an extent that a charge-densified Area is developed uniformly. The use of a developing electrode (adjacent electrode) has been suggested to to remove the edge effect and to develop a latent electrostatic image completely true to life. This is particularly important when reproducing a continuous tone. However, creating one leads to such a developing electrode in the vicinity of the upper surface of a photoelectrically conductive insulating layer in an automatic continuous device, often leads to a marked interruption in the flow of a cascade developer and a decrease in performance. this? device. . '' ■ '

The object of the invention is therefore to avoid a such edge effect using a developing electrode while maintaining the simplicity and reliability of the conventional cascade developing apparatus.

According to the invention there is a method of development of an electrostatic latent image, the cascade development method being a Cascade developer between the top surface of a photo-conductive insulating layer and a flexible one Flowing developing electrode which acts to cover the layer by gravity, and the electrostatic latent image while maintaining a constant and small space between the development electrode and the. latent electrostatic Image surface of the photoelectrically conductive insulating layer developed.

The invention is explained in more detail below with reference to the drawing.

Fig. 1 shows a side view in section of a typical embodiment of the device for practical Implementation of the method according to the invention.

Fig. 2 shows a perspective view of a development electrode, which is used for the device according to the invention.

Pig * 5 shows a cross-sectional image of an embodiment of the device suitable for practicing the method according to the invention.

BATH ORIGINAL 009834/1456

With reference to Fig. 1, which explains the basic principle of the invention, the device according to the invention comprises an electrically conductive base plate 1, a photoconductive insulating layer 2, a sheet or web-like development electrode 3j of d = r a Edge ', attached to a holder A , and a cascade developer supply means 5. The developing electrode J5 is light and naturally lowers from the attachment means by its own gravity so as to cover the upper surface of the photo-conductive insulating layer 2if. A non-sensitive material j composed of the electroconductive base plate 1 and the photoelectrically conductive insulating layer 2 is disposed obliquely as shown in Fig. 1, and the cascade developer 5 comprising a toner and a granular carrier becomes a constant amount between the fastening device 'il · and the photoelectrically conductive Hige insulating layer 2 molded so as to be uniform in the width direction of the electrically conductive base plate 1.

The cascade developer 5 falls between the developing electrode 3 and the insulating layer 2 due to its gravity. At the same time, the cascade developer 5 releases the toner to a latent electrostatic image of the insulating layer 2, thereby completing the development ^.

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1597350

The developing electrode j5- can be made of a structure of flexible electrically conductive strips which are short-circuited with one another as shown in FIG. 2 exist, or

ti h &! So. kv *. it can be in the form of a leaf or o «.

As a material for the developing electrode 5, a sieve is used preferably made of plastic wires that are chemically plated are formed, or a sieve made of thin metal wires. Better "development can be achieved if the" The lower surface of the development electrode is coated with a thin insulating layer so as to prevent the formation of eggs and a scattering or dissipation of charges * the to prevent the electrostatic latent image from forming, this derivation being due to the direct contact of the developing electrode 3 with the latent electrostatic Image from the photoelectrically conductive insulating layer 2 is due.

Fig. 3 shows a main part of the automatic continuous xerographic device * in which the decay according to the invention is used (Kaska · - the development unit) comprising a xerographic drum 10 from an electrically conductive drum 11 and one vapor-deposited layer 12 of amorphous selenium thereon, a flexible developing electrode 13 and 13 fixed to the lower end of the fixed inclined plate 3Λ

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an endless conveyor belt 15 having a plurality of paddles 16, which moves in the direction of the arrow. Numeral I7 denotes the cascade developer. This device is also equipped with a device for electrical charging, exposure, transfer, cleaning and the like. ■ (not shown) equipped. In operation of this device, the cascade developer is picked up by the 16 and to drop onto the fixed inclined plate 14 in a continuous and uniform manner

brought in the direction of its width, is then continued and
guided / falls like a cascade onto the vapor-deposited selenium layer 12, which has a latent electrostatic image on the xerographic drum 10. At the same time, the cascade developer 17 falls through a gap or a 'space between the vapor-separated selenium layer 12 and the firmly attached inclined plate I ^ and rolls down while widening the gap to a certain extent and keeping it constant'. In this way the electrostatic latent image is developed. In this apparatus, it is convenient and desirable that the amount of the flexible developing electrode I3 extends from the fixed inclined plate 14 at least to a point at which the developer 17 leaves the surface of the xerographic drum 10 due to the action of gravity and the xerographic The drum is thereby covered over its width.

BATH ORIGINAL

009834/1458

The invention is explained in more detail below with the aid of examples.

example 1

Using the so-called selenium flat plate as a photosensitive material for the llektrophotographie obtained by vacuum vapor deposition of amorphous selenium on an aluminum plate, ι-raräe this uniformly positively charged in a dark room and eincsra then correspondingly exposed to be reproduced original, zn to an electrostatic latent image »received the cascade development of this image was that;?, aus.gwführt, a Entwio.lzlv ^ p; s ^ lektr-oa e _s. As shown in Figure 1 ₀ ,, arranged> ?: l: rcu O ~ ± bcs development electrode bssteht from a Pclyamiösieb (. I: Tyio: - i) screen with a mesh aperture v - .. p is about 0.074 - ■;. ■ ; ^! _2 ~ 0 me £ ') _a .the h from Polyamlädrähfcen of oteja 3'ü / iilcroii iir: Diameter harges'& ül3.t - ^ zI Ci ^"5: x ~ s ..- ch with syllable? _: -, latt -: -. he '·; worcisri was ^ in order to siae ubsrflächeleitktiv "kait riTi ergel-G ¹ : - Eiu iCaskadeaeiitwicklsr ¹ « dQi- in "large UrafaÄiS 'i? lu' ⁱ y ~: c -: ^: ~ 9l · · -'- (eiES © lekoroSüitische Kopierniasehine ^ hi: -rges -: .-- llt. - :: - Zei-or, Corporation / ν sr JiG ^ i-, v / ir-d ^ wür-dt Vnlls ^ aLui ^ iiV.r üis Gesa ? iilfOb3r'flache v: ^ r ^ä Selsnflachpl

- 9 ■■ -. ■. ■ ■ ■■■■ - ■■. ■

after the entire cascade developer fell down, -; became the development electrode removed «The original image was made with greater accuracy and without occurrence of the edge effect even in a large area that coincides with was densified with a toner. When the surface potential of the selenium flat plate with uniform Charge is too large, sparks appear between an area of high potential of the latent electrostatic Image and the developing electrode, if they are at the

- '■ -. 7Ct "■■■■■' ■■■■" ■. '■■■' '■' Development in proximity ^ "" to each other, whereby a break in the picture is brought about »To prevent this, It proved effective to place a sheet of an insulating film between the latent electrostatic Image and insert the developing electrode and the cascade developer between the latent electrostatic Watch the picture and the insulating film »,

Example 2

This example is similar to Example 1 described above except that a polyester film with a thickness of 75 microns on which aluminum had been vapor-deposited in a vacuum was used as the developer electrode of the surface of a latent electrostatic core ηηύ ύΑ & - development wlards- in ähml'lQhmv MbIbq to achieve you 'good -ErgofenlsecHft. -BADOBlGiNAL -.

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In this developing electrode no spark appeared, even if the potential difference between the Oberfläohenpotential of selenium flat plate, and the developing electrode to was large because the surface of the latent elektrosktischen BliCJes was separated from the electrically 3sitfähigen surface of the developing electrode through the polyester film.

Example .3

A cascade development was made using a electrophotographic photosensitive drum (xerographic drum) composed of an aluminum drum and a film of amorphous vapor-deposited selenium on the outer surface thereof, in a system as shown in Fig. 5 carried out. It became the same Developer as used in Example 1 and a polyester film 75 microns thick on one surface of which Aluminum had been vapor deposited in a vacuum, was used as a development electrode ». The development electrode was attached to the lower end of an inclined plate attached and covered the surface of the drum so that the vapor-deposited aluminum-free surface (insulating surface) over dia gank © width and up to

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1537850 .- ii - ■. · ■

a position slightly below where the developer was removed, facing the drum surface due to its weight and flexibility when no developer was added, “the electrically conductive surface of the developer electrode was grounded” the cascade developer was lifted or picked up by the paddles, ) on the surface of the drum over the inclined plate cascade down dropped and supplied in this way between the drum surface and the developing electrode, whereby the developer electrode is pushed away to form a gap or clearance ■ ₀ Although the electrostatic attraction between a latent "electrostatic image on the drum and the developer electrode so iclrktj that the passage of the cascade atwlc. ::. zjs ■ ν - .. ö. ^ .- brocr-eri. This is not disadvantageous or harmful. is pushed away,

Example 4 -

A polyester film with a thickness of 75 microns, on one surface. Aluminum evaporated in a vacuum divorced wowen was in "ribbon shape."

BATHROOM OBIGlNAL

009834/145 «

and used as a developer electrode. The developer electrode was in the device according to Example 3 in arranged in such a way that one end of each tape, like shown in Fig. 2, attached and electrically shorted became. Clogging was prevented more effectively and good development was achieved through the use of such Reached developer electrode.

In all of the above examples, edge-effect-free images were obtained from. According to the procedure according to The invention therefore effectively utilizes the ability of a developer electrode to be a cascade developer fully fed and an electrostatic latent image developed with high accuracy, wjbei prevents the appearance of clogging and simplicity and reliability of the cascade developing device in use is maintained »

In addition, the method according to the invention in the Development of latent electrostatic images on one with a dispersion of resin and photoelectrically conductive zinc oxide coated paper and other photosensitive ones Materials for electrophotography can of course be used, although in all of the above examples selenium was used «

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Claims (1)

Claim :, that in which Kaskadenentwiokluhgsyerfahren a cascade developer between the upper surface of a light electrically conductive insulating layer and a flexible Entwioklerelek can * trode flow _Ä acting in the manner of covering method for developing an electrostatic latent image, characterized in that the layer due to gravity , and developing the electrostatic latent image on the photo-conductive insulating layer while maintaining a small gap between the developing electrode and the surface of the electrostatic latent image. BAD OHIG 9 * 347.14.58 Blank page