# US 4,394,432 A · Method for printing a plurality of duplicated copies from the same electrostatic charge latent image

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- Number: US 4,394,432 A
- Document ID: US4394432A
- Status: Granted
- Kind: A
- Application number: 06/268,329
- Filed: 1981-05-29
- Granted: 1983-07-19
- Earliest claimed: 1978-02-08
- Assignees: Olympus Optical Co., Ltd.
- Inventors: Masaji Nishikawa
- Web page: https://patentgrep.com/patent/US4394432A

## CPC

- G03G 13/09: using magnetic brush
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

In a method for printing in an electrophotographic manner a number of duplicated copies by repeatedly effecting developing and transferring steps for the same and single electrostatic charge latent image once formed on a charge retentive member such as a photoconductive drum, in order to compensate a variation in print density of a number of copies an amount of toner particles to be supplied to the latent image during the developing step is adjusted in such a manner that the copies have substantially the same print density. The adjustment of an amount of toner particles can be effected by changing a supply speed of the toner particles, a thickness of a magnetic brush, a distance from the magnetic brush to the latent image, etc.

## Claims

### Claim 1

An improved method of printing a plurality of duplicated copies with the aid of a single electrostatic charge latent image formed on an electrostatic charge retentive member to form an electrostatic charge latent image corresponding to an image of a document to be duplicated on a charge retentive member and developing the latent image with a developer to form a visible toned image on the charge retentive member; transferring the toned image onto an image receiving member; fixing the transferred toned image on the image receiving member; and successively repeating the developing, transferring and fixing steps for the same and single latent image so as to form a plurality of duplicated copies, the improvement comprising the step of: gradually increasing the total amount of the developer supplied to the latent image on the charge retentive member while maintaining the toner concentration substantially constant for developing the latent image in such a manner, that both a large variation in print density at a higher density part in the image and a small variation in print density at a lower density part for successive copies are simultaneously corrected.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the developer is a dry developer including toner particles and the amount of developer including toner particles applicable to the latent image is adjusted by changing the moving speed of the developer relative to the charge retentive member.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the charge retentive member is formed as a drum which rotates at a constant speed at a given position and further including the step of adjusting the amount of toner particles applicable to the latent image by moving the developing device with respect to the charge retentive drum to change the distance therebetween.

### Claim 4 (depends on 2)

The method according to claim 2, wherein developing of the latent image is accomplished with the aid of a magnetic brush developing device comprising a magnet device, a sleeve rotatably arranged around the magnet device and a doctor blade for defining a thickness of hairs of toner particles of a magnetic brush attracted on the outer surface of the sleeve, and including the step of adjustably supplying an amount of toner particles to the latent image by changing the gap between the doctor blade and the sleeve.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the developing of the latent image is carryed out by means of a magnetic brush developing device including a magnetic roller and a sleeve rotatably arranged around the magnetic roller and further including the steps of adjusting the amount of toner particles to be supplied to the latent image by moving the magnetic roller with respect to the charge retentive member so as to displace a portion of magnetic poles of the magnetic roller facing the charge retentive member.