Hitachi Metals, Ltd.

Ryuji Goto

Keitaro Yamashita

Koji Noguchi

Masumi Asanae

Hiromi Kashiwagi

Akihiko Funakawa

A developing apparatus including a magnetic conveying means 4 comprising a non-magnetic metal sleeve 7, onto which a developer containing a magnetic toner and a magnetic carrier is attracted, a permanent magnet member 8 having a plurality of magnetic poles and stationary inside the sleeve 7; a casing 1a having a developer-containing portion 5 for receiving the magnetic conveying means 4 and a toner-containing portion 3 disposed adjacent to the developer-containing portion 5 for storing the magnetic toner; and a doctor blade 10 for regulating a thickness of the developer 11 on the sleeve 7, the sleeve 7 being rotated such that the magnetic toner is attracted onto a surface of an electrostatic image-bearing member 12, further comprising a downward partition 3a and an upward partition 3b between the developer-containing portion 5 and the toner-containing portion 3 in such a positional relation that the downward partition 3a is closer to the sleeve 7 than the upward partition 3b, a developer which has not passed through a gap between the doctor blade 10 and the sleeve 7 being mixed with a freshly supplied magnetic toner in a region R defined by the downward partition 3a, the upward partition 3b, the sleeve 7 and an inner wall of the casing 1a.

Developing apparatus having mixing region

A developing apparatus including a fixed permanent magnet member 4 having a plurality of magnetic poles on the surface and a non-magnetic cylindrical sleeve 5 which is rotated around the permanent magnet member 4 at a position opposing a movable image-bearing member 1 having an electrostatic latent image on the surface, to form a developing region Z; causing a developer 3 to be magnetically attracted onto a surface of the non-magnetic cylindrical sleeve 4, and rotating the non-magnetic cylindrical sleeve 4 to convey the developer 3 into the developing region Z, and developing the electrostatic latent image with the magnetic toner 3, the moving velocity of the developer 3 in the developing region Z being higher than the peripheral velocity of the non-magnetic cylindrical sleeve 5.

Developing apparatus using magnetic developing poles having the same

The developing method of the present invention is carried out by providing a developing means comprising a non-magnetic sleeve and a permanent magnet member stationary inside the non-magnetic sleeve at a position opposing an image-bearing member having an electrostatic latent image on the surface, thereby forming a developing region; causing a developer to be magnetically attracted onto a surface of the non-magnetic sleeve, the developer comprising magnetic toner consisting of a binder resin and magnetic powder and capable of being charged at a particular polarity and a magnetic carrier having a relatively large conductivity; and rotating the non-magnetic sleeve to convey the developer to the developing region, thereby developing the electrostatic latent image with the magnetic toner. The non-magnetic sleeve is rotated in the same direction as the image-bearing member in the developing region at a ratio of a surface moving velocity (V.sub.1) of the non-magnetic sleeve to a surface moving velocity (V.sub.2) of the image-bearing member (V.sub.1 /V.sub.2)=1.5-5.0. A center of a developing magnetic pole of the permanent magnet member is deviated by 2.degree.-12.degree. toward the downstream side from a line connecting the closest points of the non-magnetic sleeve and the image-bearing member.

Magnetic brush developing method

A magnetic developer comprising magnetic toner particles each comprising a binder resin, magnetic powder and a first charge-controlling agent, and magnetic carrier particles in mixture, and further containing 0.05 to 1 part by weight of a second charge-controlling agent being provided on the outer surfaces of the magnetic toner particles on the basis of 100 parts by weight of the magnetic toner particles has better triboelectric characteristics and a highly stabilized image density in the continuous development.

Magnetic developer

An apparatus for developing electrostatic latent images with a two-component developer consisting of carrier and toner, comprising (a) a developer container, (b) a magnetic roll provided in the container, comprising a permanent magnet and a non-magnetic sleeve, (c) a hopper mounted on the container for replenishing toner to the container, (d) a roller provided in the container near its wall on the opposite side to the magnetic roll for mixing the developer with the toner replenished from the hopper and stirring them, (e) a device having a detection surface for detecting the concentration of toner in the developer. The detection device is mounted on the wall of the container such that the detection surface is located near the mixing roller to ensure the developer to flow smoothly and stably between the mixing roller and the detection surface.

Developing apparatus

A process for depositing magnetic toner material on electrostatic latent images formed on an image bearing surfaces includes the steps of conveying toner to the developing zone via a magnet roll having a shell and coaxial permanent magnet member rotating in the same directions. In the region of the developing zone, the toner is subjected to both an A.C. magnetic field and an applied A.C. electrical field so as to render the toner electroconductive. The A.C. electrical field has a peak voltage greater than the dark voltage of the latent image, but less than 3,200 volts, and a frequency greater than v/0.3 where v is the advancing speed of the image bearing surfaces in relation to the magnet roll.

Process for depositing magnetic toner material on electrostatic latent

A method of electrophotography in which an electrostatic latent image is formed on the surface of a material layer and a non-magnetic cylinder is provided to confront the surface of said material layer. A permanent magnet roll made up of a plurality of symmetrically arranged magnetic poles extends axially in said cylinder. A magnetic brush is formed by attracting a semiconducting or insulating magnetic toner onto the cylinder with the aid of a magnetic attraction force of the permanent magnet roll. The cylinder and permanent magnet roll are moved relative to each other to permit the magnetic brush to slide along the surface of the material layer thereby to allow the magnetic toner to adhere at predetermined position on the surface of said material layer, and a toner image is transferred onto a transferring member and is then subjected to fixing. The cylinder and the permanent magnet roll are rotated in the same direction so that the magnetic toner is moved in the same direction as that of said material layer at a speed less than 100 mm/sec irrespective of the speed of movement of the surface of said material layer at a development section.

Electrophotography using a magnetic brush

A magnet-brush development process in which the amount of developer powder supplied to a development zone is self-controllable by the rotation of a magnet roll. A permanent magnet member and the shell rotate at different speeds in the same direction in such a manner that developer powder, as a whole, is conveyed on the shell in the direction opposite to the rotation of the magnet roll from a doctor spacing of a developer vessel to an image-bearing material. By controlling the doctor spacing to be larger than the gap between the image-bearing material and the magnet roll, an accumulation of the developer powder occurs on the shell between the doctor spacing and the development zone and is kept to be substantially constant. At the accemulation, an understream of powder moves in the direction of roll-movement towards the powder supply.

Magnet-brush development process of electric pattern images

A device for removing residual toner from the surface of a photoreceptor after the transfer of a toner image from the photoreceptor surface to another surface comprises a fur brush for lightly sweeping residual toner particles on the surface of the photoreceptor to align the particles substantially in streaks along the sweeping direction and a magnetic roll for picking up the aligned toner particles by the magnetic attraction force of the magnetic roll. The fur brush is positioned adjacent to, and in a slight contact with, the surface of the photoreceptor. The magnetic roll is disposed adjacent to the surface of the photoreceptor and at the trailing side of the fur brush along the path of relative movement with the photoreceptor.

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Fukaya, Japan

Ryuji Goto