Fujitsu Corporation

Junzo Nakajima

Masatoshi Kimura

Masahiro Wanou

Kunihiko Sato

Mikio Amaya

Sachio Sasaki

Tadashi Matsuda

Masakatsu Horie

Akihiko Ishii

Masayuki Hida

Tetsurou Nakashima

A process unit to be loaded into an image forming apparatus, includes at least a photosensitive drum to be rotated and a conductive brush type charger for uniformly charging a surface of the photosensitive drum. The conductive brush fibers having tips which touch the surface of the photosensitive drum and apply a charge voltage of 500 V to 1,500 V to the surface of the photosensitive drum through the conductive brush fibers for uniformly charging the surface of the photosensitive drum.

Process unit for image forming apparatus, including a charging brush

A brush type charging unit having a constant-current regulated power supply for supplying a constant current to a moving photosensitive medium through a conductive brush fiber contacting the moving photosensitive medium for charging the photosensitive medium uniformly such that the charged potential varies within a range smaller than 10 V when an atmospheric condition changes from 5.degree. C.-20% RH to 35.degree. C.-80% RH. The constant-current regulated power supply has a pulse removing circuit for charging the moving photosensitive medium uniformly even when a few pin-holes exist in the photosensitive medium. A fiber element has a resistance between 4.5.times.10.sup.7 ohm and 1.times.10.sup.13 ohm when the fiber element has 1 denier in size and 1 mm in length, for charging the photosensitive medium and avoiding burning of the fiber element.

Brush contact type charging unit in an image forming apparatus

A compact and simple structured electrophotographic printing apparatus having a single magnetic developer, in which an accumulation of toner particles is formed on a photosensitive member at a downstream position from the magnetic developer. The accumulation of the toner particles is formed by moving a photosensitive film and a magnetic brush in rubbing contact with the film in mutually opposite directions, or by deforming a magnetic field generated by the magnetic developer, using a magnetic piece. A recording electrode is disposed on a sleeve of the magnetic developer and facing the photosensitive film. Bias voltages, having polarities opposite to each other with respect to the photosensitive film, are respectively applied to the recording electrode and the sleeve. An optical beam is projected onto the photosensitive film in a region facing the recording electrode. Thus, with the aid of toner particles located between the recording electrode and the photosensitive film and the accumulation of the toner particles, sensitizing, developing and scavenging are carried out simultaneously, and thus a toner image is produced on the photosensitive film. For a magnetic developer having a rotatable sleeve, a specially designed recording electrode is disclosed. The photosensitve member may be in the form of a solid flat plane, a drum, or a flexible belt-like film.

Compact electrophotographic printing apparatus having an improved

An electrostatic recording apparatus is provided which comprises a recording electrode with a plurality of stylus electrodes and a developing device with a back electrode provided on opposite sides of a recording medium. The recording apparatus is capable of simultaneously processing the forming of and development of a latent image by using the recording electrode which has a magnetic piece embedded at a tip portion thereof. A magnetic field is concentrated in its path and is increased in a narrow gap region between the recording electrode and the back electrode. Toner chains of magnetic particles in the developing process can easily stand upright on the back electrode, and can thus easily and uniformly contact the recording medium. Dot defects on a formed image, are therefore, avoided. The present invention is directed to several embodiments of the magnetic piece and the manner of embedding the magnetic piece in the recording electrode.

Electrostatic recording apparatus with improved recording electrode

An electrophotographic printing apparatus employs a laminated, photosensitive medium including transparent supporting and conducting layers and a photosensitive layer defining the top surface of the medium, on which a toner image is formed. A first developer, maintained at a voltage of the same polarity as the toner particles, forms a uniform layer of charged toner particles on the surface of the photoconductive layer, the charged particles adhering to the surface. Simultaneously or subsequently, an optical beam is projected onto the photoconductive layer in accordance with the image to be printed, rendering the selectively exposed portions sufficiently conductive to permit charges of opposite polarity to be injected into the photoconductive layer from the conducting layer; the photoconductive layer establishes trapping potential levels therein, permitting the charges to traverse the layer to positions adjacent the top surface thereof. Upon extinguishing the optical beam, the photoconductive layer reverts to a nonconductive state, fixing the trapped charges in position as a laten electrostatic image. The latent electrostatic image establishes a field, or Coulomb force, which closely adheres the oppositely charged toner particles to the surface. In a second developing step, a developer, to which is applied a voltage of opposite polarity relative to that of the toner particles, then removes the toner particles from the nonexposed portions of the surface; the toner particles on the exposed portions of the surface are more firmly adhered thereto by virtue of the latent electrostatic image and thus a substantial portion thereof remain, providing a high contrast toner particle image for subsequent transfer to a suitable recording medium.

Method and apparatus for forming a toner image in electrophotographic

First and second optical latent image forming devices form an electrostatic latent image directly on a homogeneously charged recording medium surface. Each of the first and second optical latent image forming devices has the capability of discharging almost half the initial charges of the recording medium. The discharging effect of the first and second optical latent image forming devices forms the combined electrostatic latent image.

Electrophotographic copying printer

A direct imaging method wherein a recording electrode comprising a plurality of electrode styli and a magnetic toner developer are provided on opposite sides of an insulating recording medium, such that an image is printed on the recording medium through direct adherence of magnetic toner on the recording medium when a voltage is applied across the recording electrode and magnetic toner developer. A proper gap discharge is generated between the recording electrode and the recording medium by forming a very narrow gap between the recording electrode and the recording medium. The present invention also comprehends adhering charges to the rear side of the recording medium by means of such gap discharge and the magnetic toner of the magnetic toner developer is reliably held to the surface of the recording medium by means of such charges.

Direct imaging method and equipment using recording electrode, magnetic

An electrophotographic recording device suitable for a Form Overlay System, by which a latent image is formed on a surface of a light-sensitive recording medium, consisting of a first area which is maintained at an original potential, a second area which is maintained at a partially reduced potential and a third area which is maintained at a potential of zero.

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Yokohama, Japan

Junzo Nakajima