Photocopying – Projection printing and copying cameras – Combined with or convertible to a contact printer
Patent
1987-04-14
1989-03-21
Braun, Fred L.
Photocopying
Projection printing and copying cameras
Combined with or convertible to a contact printer
355 14R, 430120, G03G 1508, G03G 2100
Patent
active
048148342
ABSTRACT:
An electrophotographic apparatus capable of operating both in a mode for obtaining a positive image from a negative original and in a mode for obtaining a positive image from a positive original and capable of constantly controlling the image density in either mode. The apparatus can be used selectively in either mode, and in both modes the image density can be controlled by a common operating member. The apparatus, which forms images on a recording medium by the rotation of a drum-shaped image bearing member, includes a device for forming an electrostatic latent image on the image bearing member; a development device for developing the latent image with toners charged in the same polarity as that of the image bearing member; a developing bias voltage generating device for applying a bias voltage to the development device; a corona discharge device for effecting corona discharge on a transfer station to transfer the toner image formed on the image bearing member to the recording medium; a detecting device for detecting a corona-discharged area and the other area on the image bearing member; and a device for controlling the bias voltage in correspondence with the area detected by the detecting device.
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Endo Makoto
Saito Yoshihiro
Braun Fred L.
Canon Kabushiki Kaisha
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