US 4,058,637 A · Electrostatic developing method

Abstract

Method is disclosed for developing electrostatic latent images, utilizing a developer supply unit formed of a liquid repellent layer having a thickness in the range of 3.mu. to 400.mu. (preferably 5.mu. to 330.mu.), and a substrate, and having uniformly distributed pores disposed therethrough. A liquid developer is supplied to the back surface of this unit, and an exposing unit is disposed to form electrostatic latent images onto the front surface of the developer supply unit. As a result, the liquid developer applied to the back surface of the liquid repellent layer is distributed on the front surface by the action of the electric field established by the latent image.

Drawings

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Drawings

Claims3

Dependent claims

A method of electrostatically printing an original image with a liquid developer onto an image bearing medium which comprises the steps of:

providing a composite assembly having opposite facing first and second surfaces respectively defined by a first layer, which is hydrophilic with respect to said liquid developer, and a second layer which is hydrophobic with respect to said liquid developer and disposed upon said first layer to form said composite assembly, said composite assembly having a plurality of uniformly distributed fine pores extending therethrough from said first surface to said second surface, the size of said fine pores are in the range of 10.mu. to 100.mu., the thickness of said second layer being in the range of 3.mu. to 400.mu. and so selected as to prevent said liquid developer from easily entering into the pores of said second layer;
supplying said liquid developer to said first surface of said composite assembly to flow into the pores of said first layer;
disposing an image bearing medium, having an electrostatic latent image formed thereon, adjacent to said second surface on said composite assembly so that portions of said second surface of said composite assembly are exposed to the electric field emanating from said electrostatic latent image formed on corresponding portions of said image bearing medium thereby causing the liquid developer in pores of said first layer to wet the inside surfaces of corresponding ones of the pores of said second layer in said exposed portions to flow therethrough and to exude onto said exposed portions of second surface thereof;
and
contacting said image bearing medium with said composite assembly to transfer the liquid developer on said exposed portions of said second surface of said composite assembly onto said electrostatic latent image formed on corresponding portions of said image bearing medium.

2 more elements

A method of electrostatically printing an image on an electrostatic image bearing medium with a liquid developer comprising the steps of:

providing a composite assembly having opposite facing first and second surfaces respectively corresponding to a surface of a substrate which is hydrophilic with respect to said liquid developer and a layer of material which is hydrophobic with respect to said liquid developer, disposed upon said substrate to form said composite assembly, said composite assembly having a plurality of uniformly distributed fine pores extending through said substrate and said layer to provide communication between said first and second surfaces, the size of said fine pores being in the range of 10.mu. to 100.mu., the thickness of said second layer being in the range of 3.mu. to 400.mu.;
supplying said liquid developer to said first surface of said composite assembly to flow said developer into the pores of said first layer;
disposing an image bearing medium, having an electrostatic latent image formed thereon, adjacent to said second surface of said composite assembly so that portions of said second surface of said composite assembly are exposed to the electric field emanating from corresponding portions of said electrostatic latent image formed on said image bearing medium;
said hydrophobic property of said layer being such that a contact angle greater than 90.degree. is formed in the pores of said layer with respect to said supplied liquid developer when not exposed to an electric field and said property being such that a contact angle less than 90.degree. is formed in said pores with respect to said supplied liquid developer when exposed to an electric field;
said step of disposing an image bearing medium causing the liquid developer in pores of said substreate to wet the inside surfaces of corresponding ones of the pores of said hydrophobic layer in said exposed portions to flow therethrough;
contacting said image bearing medium with said composite assembly to transfer the liquid developer on said exposed portions of said second surface of said composite assembly onto said electrostatic latent image formed on corresponding portions of said image bearing medium.

3 more elements

Dependencies are inferred from the claim text.

Description3,486 words

Summary656 words

#1. Field of the Invention

#This invention relates to methods of developing electrostatic, latent images and corresponding developing apparatus, and in particular to those methods of liquid development.

#2. Description of the Prior Art

Brief description of the drawings7 figures

#While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, a preferred embodiment is disclosed in the following detailed description taken in conjunction with the accompanying drawings, in which:

#FIG. 1 is a cross-sectional view of the contact angle of a liquid drop on the surface of a liquid repellent film;

#FIG. 2 is a cross-sectional view of the change of the said contact angle, when the liquid repellent film is charged;

Detailed description2,671 words

#Referring now to FIG. 1, there is shown a liquid drop 2 of water disposed on an uncharged liquid repellent film 1. The contact angle .theta. between the film surface uncharged and the drop is greater than 90.degree. and the film surface is not wetted. Referring to FIG. 2, however, the liquid repellent insulating film is charged; as a result the contact angle .theta. decreases to less than 90.degree., and the liquid drop is able to wet the film surface. The wetting effect is dependent upon the liquid repellent intensity of the film surface, the kind of liquid, and the applied voltages. When a water drop is placed on a film of 3-fluoro ethylene chloride resin, for example, the contact angle .theta. of an uncharged film is 108.degree.. When a film of this material is charged to -500V, the angle .theta. decreases to 56.degree. and the film surface is wetted.

#FIG. 3 is a perspective view of a developer supply unit used in accordance with the teachings of this invention. A layer 5, is a material that is hydrophobic with respect to the aqueous liquid developer and consequently liquid repellent. The layer 5 has a specified thickness and is disposed on a substrate 4. The substrate is formed of a material that is hydrophilic with respect to the liquid developer. The layer 5 and the substrate 4 form a composite assembly. A plurality of minute pore openings 6 extend through the composite assembly and are distributed uniformly at close spacings over the entire surface thereof. The composite assembly shown in FIG. 3 is utilized as a developer supply unit 7.

#FIG. 4 shows the arrangement of the liquid developer supply unit 7 indicated in FIG. 3 in relation to an electrostatic-latent image forming unit 8. The electrostatic latent image forming unit 8 is a sensitive plate composed basically of a conductive supporting substrate 9, a photoconductive layer 10, and an insulating layer 11, as illustratively described in U.S. patent application Ser. No. 528,624, now abandoned. The photosensitive plate 8 may be charged with electrostatic latent images 3 (indicated by dotted lines), and disposed in the front of the developer supply unit 7.

Facts

Application

05/604,098Filed 13 Aug 1975 · continuation

Priority

JA 46-707618 Feb 1971

Granted

15 Nov 1977

Term ended

15 Nov 1994

Estimated · how

Pre-1995 term; greater of 17 years from grant or 20 years from filing when eligible. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification3 codes

G03G 9/18
Developers not provided for in groups G03G9/06 - G03G9/135, e.g. solutions, aerosols: differentially wetting liquid developers
G03G 15/102
For wetting the recording material: for differentially wetting the recording material
G03G
Electrography

Electrostatic developing method

Life of this patent

Electrostatic developing method

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims3

Description3,486 words

Drawings

Classification3 codes

Life of this patent

Description3,486 words