Apparatus for controlled delivery of magnetic toner

• US 4,496,240 A
• Filed: 10/17/1983
• Issued: 01/29/1985
• Est. Priority Date: 09/01/1980
• Status: Expired due to Fees

• Current Assignee: Hitachi Metals (Thailand) Ltd.
• Original Assignee: Hitachi Metals (Thailand) Ltd.
• Inventors: Yamashita, Keitaro, Kashiwagi, Hiromi
• Primary Examiner(s): MOSES, RICHARD L
• Application Number:
  US06/541,492
• Time in Patent Office: 470 Days
• Field of Search: 355/14 D, 355/3 DD, 118/688, 118/689, 118/690, 118/657, 118/658
• US Class Current: 399/53
• CPC Class Codes: G03G 15/09 using magnetic brush

Abstract

A developing apparatus for developing an electrostatic latent image by means of a magnetic toner. The apparatus includes a non-magnetic cylindrical sleeve accommodating a first magnet roll and disposed to face the surface of a photosensitive roll, a developing tank for supplying the non-magnetic sleeve with the magnetic toner, and a blade disposed at the outlet of the developing tank for adjusting the thickness of the magnetic toner which is conveyed on the surface of the sleeve due to a relative rotation between the sleeve and the first magnet roll. The apparatus further includes a detector disposed at the upstream side of the blade as viewed in the direction of convey of the magnetic toner for detecting the amount of the magnetic toner, a second magnetic roll disposed at the toner outlet of a toner tank for controlling the amount of the magnetic toner supplied through the toner outlet to the developing tank, and a motor for selectively rotating the second magnetic roll in accordance with a signal produced by the detector.

Claims

1. An apparatus for developing an electrostatic latent image by means of a single component magnetic toner, having a non-magnetic cylindrical sleeve disposed to oppose a surface of a photo-sensitive member, and a magnetic roll disposed in said sleeve and having a plurality of magnetic poles, said apparatus further comprising:

a container provided with developing tank means for receiving the magnetic toner to be supplied onto the non-magnetic cylindrical sleeve and for receiving any excess magnetic toner carried by said sleeve and not transferred to said latent image, said container further including toner supply tank means for holding a supply of the magnetic toner, said toner supply tank means being in communication with said developing tank means via a communication portion including a wall;

a doctor blade disposed at a toner outlet of said developing tank means and adapted to adjust the thickness of a layer of the magnetic toner conveyed to said latent image on said non-magnetic sleeve due to relative rotation between said non-magnetic sleeve and said magnet roll;

means for detecting the amount of the magnetic toner attracted onto said non-magnetic sleeve and for generating a signal in response to said detected amount, said detecting means being disposed in the developing tank means upstream of said doctor blade as viewed in the direction of conveyance of the magnetic toner;

rotating means for supplying the magnetic toner from the toner supply tank means to the developing tank means, said rotating means comprising a magnet roll with a plurality of magnetic poles provided on a surface thereof, and being disposed to control the flow of toner through said communication portion, said magnet roll positioned adjacent said communication wall and being rotatable in a predetermined direction to move the magnetic toner from said toner supply tank means to said developing tank means along said wall; and

means for actuating said rotating means in accordance with the signal generated by said detecting means, thereby controlling the delivery of the magnetic toner from said toner supply tank means to said developing tank means based on the amount of toner in said developing tank means.

2. A developing apparatus as claimed in claim 1, wherein said actuating means are actuated such that the magnet roll of said rotating means is rotated until said detected amount of magnetic toner reaches a predetermined level, and the magnet roll of said rotating means is stopped whenever said detected amount of magnetic toner reaches said predetermined level.

3. A developing apparatus as claimed in claim 1, wherein said magnet roll and said magnetic roll are of substantially equal length.