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Publication numberUS3799340 A
Publication typeGrant
Publication dateMar 26, 1974
Filing dateDec 2, 1971
Priority dateDec 2, 1970
Also published asCA944204A1, DE2159853A1
Publication numberUS 3799340 A, US 3799340A, US-A-3799340, US3799340 A, US3799340A
InventorsSadamatsu S, Tamai Y
Original AssigneeFuji Photo Film Co Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Refining photoconductive particle
US 3799340 A
Abstract
Apparatus for refining composite photoconductive particles comprising transparent cores with photoconductive films disposed thereon, the apparatus comprising means for uniformly charging and dispersing the composite particles in a layer on an electroconductive member so that the composite particles are electrostatically attracted to the electroconductive member, means for uniformly exposing the layer of composite particles to radiation within the sensitive wavelength region thereof to reduce the electrostatic attraction of desired composite particles for the electroconductive member, and first removing means for removing the desired composite particles from the electroconductive member.
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Description  (OCR text may contain errors)

United States Patent [1 Tamai et al.

[ REFINING PHOTOCONDUCTIVE PARTICLE [75] Inventors: Yasuo'Tamai, Asaka; Shigeru Sadamatsu, Odawara, both of Japan 73 Assignee: Fuji Photo Film Co., Ltd.,

Kanagawa, Japan 22 Filed: Dec. 2,1971 21 Appl. No.: 204,055

[30] Foreign Application Priority Data Dec. 2, 1970 Japan 45-106638 [52] US. Cl 209/127 R [51] Int. Cl. B03c 7/08 [58] Field of Search 209/127 R, 128, 129,131; 15/15 [56] References Cited UNITED STATES PATENTS 2,924,519 2/1960 Bertelsen 1l7/17.5 1,354,063 9/1920 Payne 1. 209/131 3,308,948

3/1967 Barthelemy 209/127 R Mar. 26, 1974 Breakiron et al. 209/127 R Robinson 209/129 Primary Examiner-Tim R. Miles Assistant Examiner-Ralph J. Hill Attorney, Agent, or Firm-Gerald J. Ferguson, Jr.

[ 5 7 ABSTRACT Apparatus for refining composite photoconductive particles comprising transparent cores with photoconductive films disposed thereon, the apparatus comprising means for uniformly charging and dispersing the composite particles in a layer on an electroconductive member so that the composite particles are electrostatically attracted to the electroconductive member, means for uniformly exposing the layer of composite particles to radiation within the sensitive wavelength region thereof to reduce the electrostatic attraction of desired composite particles for the electroconductive member, and first removing means for removing the desired composite particles from the electroconductive member.

7 Claims, 5 Drawing Figures PAIENTEDIARZB I974 FIG. 2

FIG. I

FIG. 4

REFINING PHOTOCONDUCTIVE PARTICLE BRIEF DESCRIPTION OF THE DRAWING FIGS. 1 to" 4 are the cross-sectional views of photoconductive particles of different shapes.

FIG. 5 is a cross-sectional side view of a device embodying this invention.

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in electrophotographic process, and particularly to a process for refining photoconductive particles;

One of the electrophotographic process already known utilizes the combination of photoconductive particles and electroconductive plate as disclosed for example in Japanese Patent Publication No. 12385/69 and 8838/70. Said process consists of the steps of either scattering the photoconductive particles to form a layer thereof on an electroconductive material and then electrostatically charging thus formed layer or dispersing photoconductive particles previously charged on said material to form a layer of said particles, then subjecting said layer to imagewise exposure, removing the particles of which electrostatic charge is dissipated by said exposure and fixing the remaining particles thereon or after transferring to other suitable materials.

The invention relates to the refining process of the photoconductive particles of the above mentioned type after the manufacture thereof and/or after the repetitive use thereof.

The photoconductive particles for use in electrophotographic process of the above-mentioned type contain core materials. In this invention, the core materials should be considerable transparent (absorption coefficient not exceeding l.3 X mm") to the radiation of the major part of sensitive wavelength region of the photoconductive materials used in said process.

Said core material can be composed of glass, thermoplastic resin, solvent soluble resin, metal oxide, etc. Also said photoconductive material can be those oridinarily employed in-the electrophotographic process of the above mentioned type, such as selenium, cadmium sulfide, zinc sulfide, anthracene, zinc oxide etc., orthe mixture thereof with insulating resin.

- FIG. 1 shows the enlarged cross section of photoconductive particles preferred for use in the electrophotographic process of the above-mentioned type. In FIG. 1, a transparent core 11 is uniformly covered with an insulating photoconductive layer 12. Such particles as shown in FIG. 1 stick to an electroconductive plate by electrostatic attractive force when electrostatically chargedin a dark place, and efficiently lose the electrostatic charge thereon when exposed to light and becomes removable from said electroconductive plate.

FIG. 2 shows the enlarged cross-section of photoconductive particles formed in the course of manufacture of said particles and provided with unpreferable shape. Such particlesdo' not contain transparent core material therein but consist exclusively of insulating photoconductive material 13. Such particles as shown in FIG. 2 also stick to an electroconductive plate by electrostatic attractive force when electrostatically charged in a dark place, but do not easily lose the electrostatic charge even when exposed to light and thus remain unremovable on said plate. That is to say, such particles 1 are provided with far lower sensitivity to light compared with the particles as shown in FIG. 1, and the presenceof the unpreferred particles in those as shown in FIG. 1 gives rise to elevated fog level.

FIG. 3 shows the enlarged cross-section of particles of also unpreferable shape. In this case the core material 11 is not sufficiently covered with insulating photoconductive material 12. Such particles are formed either in the manufacturing process thereof or in the repeated use thereof in the electrophotographic process of the above-mentioned type. When the core material 11 is composed of a substance provided with electric insulating materials such as plastics or glass, such particles do not easily lose the electrostatic charge thereon even under light exposure becausesaid core material 11 is exposed on the surface as shown by 14, 14' and 14", and therefore become difficultly removable. Consequently, such particles also lead to fogging.

FIG. 4 shows the enlarged cross-section of photoconductive particles of also unsatisfactory performance. In this case the core material 11 is completely covered with the insulating photoconductive layer 12, but the surface thereof is contaminated with material of low electric resistance 21, 21 and 21". Such particles show significantly lowered charge retaining ability, and therefore cannot be deposited on an electroconductive plate by means of charging operation in a dark place. Consequently, an electrophotographic process of the above-mentioned type carried out with photoconductive particles containing such particles willonly provide defective reproductions.

The object of this invention is to provide a process for eliminating the particles of unsatisfactory or unpreferred property as shown in FIGS. 2 to 4 from the photoconductive particles to obtain particles of desirable performance.

This invention enables not only to remove the particles of undesirable properties as shown in FIGS. 2 to .4 formed in the course of manufacturing photoconductive particle, but also to remove the particles of undesirable properties formed by the repetitive use of said photoconductive particles. Besides the process of this invention enables to remove insulating or electroconductive alien particles dust during the repetitive use of photoconductive particles.

More specificially this invention is to provide a process for refining the photoconductive particles containing core material being considerably transparent (absorption coefficient not exceeding 1.3 X 10 mm") to the radiation of major portion of sensitive wavelength range of the photoconductive material employed thereon, which comprises either dusting said particles on a electroconductive plate and electrostatically charging the layer thus formedof said particles or dusting said particles electrostatically charged in advance on said plate, then mechanically removing the particles provided withweaker electrostatic attractive force, exposing said layer of particles uniformly to a radiation within the sensitive wavelength range thereby dissipating the sticking force of photoconductive particles to said electroconductive plate and finally collecting the remaining particles on said plate, thereby to fractionate the particles according to the change of sticking force thereof before and after the exposure to radiation.

More'practically the change of sticking force of the photoconductive particles to the electroconductive plate is utilized as follows:

I. The particles contained in the particle layer but not chargeable are removed by utilizing the reduced sticking force thereof to the electroconductive plate. It is therefore made possible to eliminate the particles of significantly low charge retaining ability as shown in FIG. 4 or electroconductive or low-resistance dust mixed in the particles during the course of repetitive use thereof. Practically this operation is realized by inclining the plate holding charged particle layer thereon thereby removing the undesirable particles and dust by gravity and/or blowing air stream to said particle layer to remove such undesirable particles and dust.

II. The satisfactory photoconductive particles as shown in FIG. 1 are collected by exposing said particles to radiation thereby dissipating the sticking force thereof to the electroconductive plate. It is thus made possible to collect the particles adapted for use in the electrophotographic process utilizing the photoconductive particles of the above-mentioned type. The particles sticking on the electroconductive plate lose the electrostatic attractive force thereof'by uniform exposure to light and then are collected by gravity, air stream or suitable vibration.

The defective particles as shown in FIGS. 2 and 3 which do not lose the electrostatic charge thereof by the radiation still stick on said electroconductive plate. Thus, the photoconductive particles of lower sensitivity or having exposed core material and insulating dust mixed in the course of repetitive use remain on the electroconductive plate. Such remaining particles are removed from said electroconductive plate by mechanical removing such as with brush and/or blowing of strong air stream. Such operation can be combined with the steps of dissipating the charge on such particles such as corona discharged, blowing of ionized gas stream, radiation, etc.

From practical point of view, the electroconductive plate is preferably used repeatedly, and thereby conveniently formed into an endless belt. Such electroconductive plate can be composed of metal plate, electroconductive rubber, metal plate lined with flexible material, etc.

The device for embodying this invention will be explained in reference to attached FIG. 5.

The container 31 contains photoconductive particles 32 freshly manufactured or containing undesirable particles as the result of repetitive use thereof. Said photoconductive particles 32 are scooped up by the roller 33 from the bottom of said container 31 and are made to fall.

Uniform distribution is realized by the air stream from the dust 34, which is blown from a slit 36 provided on a cushioning box 35 to the falling particles. Said falling particles are electrostatically charged by the corona discharge generated by a corona electrode 37, thereby to form a charged particle layer 39 on an electroconductive belt 38, which is driven by the driving rollers 40, 41 and 42. Also provided are the rollers 43 which are in contact with the both side portions of said belt. Contaminated particles as shown in FIG. 4 and electronconductive or low resistance dust contained in the particle layer are removed therefrom by the air stream supplied from a duct 44 and collected in a container 45 of reduced pressure. The electroconductive particles thus collected are shown by 46.

Then the particle layer on the endless belt is exposed to light uniformly by a light source 48 located in the lamphouse 47. The photoconductive particle lose the sticking force and fall apart from the belt 38 by the gravity or by the air stream from the duct 50, then brought into a container 49 of reduced pressure and finally collected by a cyclon etc.

The particles retaining electrostatic charge still after said exposure and insulating dust, which are still remaining on the electroconductive plate 38, are wiped off and removed by a brush 52 provided in a casing 51 of reduced pressure. Thus it is made possible to remove the undesirable particles and dust contained in the photoconductive particles.

The refining process according to this invention is applicable both for refining the photoconductive particles after the manufacture thereof and for restoring the performance of the photoconductive particles after repetitive use thereof.

This invention, therefore, enables not only to dispense with the special classification process thus far required after the manufacture of photoconductive particles but also to prolongate the lifetime of the photoconductive particles, and thus have an elevated industrial value.

What is claimed is:

l. A process for refining photoconductive particles for use in electrophotographic process and containing core material having an-absorption coefficient not exceeding 1.3 X 10 mm to the radiation of the major part of the sensitivity wavelength range of the photoconductive material employed thereon, which comprises either dusting said particles on an electroconductive plate and electrostatically charging thus formed particle layer or dusting said particles electrostatically charged in advance on said plate to form a layer thereon, mechanically removing particles scarcely charged by utilizing the reduced sticking force thereof to said electroconductive plate, then exposing said particles layer uniformly to light covering whole sensitive wavelength range or a part thereof thereby dissipating the sticking force of said particles to said plate, and finally collecting said photoconductive particles.

2. Apparatus for refining composite photoconductive particles comprising transparent cores with photoconductive films disposed thereon, said apparatus comprising:

means for uniformly charging and dispersing said composite particles in a layer on an electroconductive member so that said composite particles are electrostatically attracted to said electroconductive member;

means for uniformly illuminating all of said layer of composite particles to radiation within the sensitive wavelength region thereof to reduce the electrostatic attraction of desired composite particles for said electroconductive member with respect to that of undesired composite particles so that said desired particles are differentiated from said undesired particles in accordance with their respective electrostatic attractions for said electroconductive member after they have both been subjected to said uniform illumination step; and first removing means for selectively removing said desired composite particles from said electroconductive member. 3. Apparatus for refining composite photoconductive particles comprising transparent cores with photoconductive films disposed thereon, said apparatus comprising:

means for uniformly charging and dispersing said composite particles in a layer on an electroconductive endless belt so that said composite particles are electrostatically attracted to said electroconductive endless belt; means for uniformly exposing said layer of composite particles to radiation within the sensitive wavelength region thereof to reduce the electrostatic attraction of desired composite particles for said electroconductive endless belt; and first removing means for removing said desired composite particles from said electroconductive endless belt; I

second removing means for removing the undesired composite particles remaining on said electroconductive endless belt after said desired composite particles have been removed therefrom and before the composite particles are dispersed thereon, said undesired particles exhibiting substantially more electrostatic attraction for said electroconductive endless belt than said desired particles.

4. Apparatus as in claim 3 where said second removing means comprises a brush disposed within a chamber maintained at reduced pressure.

5. Apparatus as in claim 3 where said first removing means comprises a container so disposed with respect to said endless belt that said desired composite particles fall because of gravity into said container.

6. Apparatus for refining composite photoconductive particles comprising transparent cores with photoconductive films disposed thereon, said apparatus comprising:

means f0 uniformly charging and dispersing said composite particles in a layer on an electroconductive member so that said composite particles are electrostatically attracted to said electroconductive member;

means for uniformly exposing said layer of composite particles to radiation within the sensitive wavelength region thereof to reduce the electrostatic attraction of desired composite particles for said electroconductive member; and

first removing means for removing said desird composite particles from said electroconductive member;

third removing means for removing further undesired composite particles before said first removing means removes said desired composite particles, said further undesired particles exhibiting substantially less'electrostatic attraction for said electronconductive member than said desired particles.

7. Apparatus as in claim 6 where said third removing means comprises means for blowing a jet of air onto said layer of composite particles to loosen said further undesired particles from said electroconductive member.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1354063 *Aug 7, 1919Sep 28, 1920Payne Clarence QApparatus for grading finely-comminuted materials
US2924519 *Dec 27, 1957Feb 9, 1960IbmMachine and method for reproducing images with photoconductive ink
US3308948 *Feb 20, 1963Mar 14, 1967Barthelemy Roger EHigh voltage separation of fine particles
US3322275 *Jul 10, 1964May 30, 1967Carpco Res & Engineering IncHigh tension separation of materials
US3662884 *Oct 20, 1969May 16, 1972Xerox CorpMethod and apparatus electrostatically classifying toner particles
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4923581 *Nov 28, 1988May 8, 1990Precision Image CorporationToner recycling by counterflow
US5746320 *Jun 12, 1995May 5, 1998Tooyota Tsusho CorporationFriction electrifying-type electrostatic sorting apparatus
US6921618 *Mar 17, 2003Jul 26, 2005Fuji Xerox Co., Ltd.Light sensitivity, electrophotographic characteristics giving images of good qualities, and dispersibility in binder resin
CN101887043BJul 19, 2010Nov 7, 2012中南大学Renewable solid working electrode for electrochemical analysis
WO1989001189A1 *Jul 6, 1988Feb 9, 1989Precision Images CorpLiquid toner recycling system and method
Classifications
U.S. Classification209/127.1
International ClassificationG01N27/60, G03G9/00, G03G15/05, G03G5/08
Cooperative ClassificationG03G5/08, G01N27/60, G03G9/00
European ClassificationG01N27/60, G03G9/00, G03G5/08