The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 04, 1984
Filed:
May. 28, 1982
Takashi Kitamura, Yokohama, JP;
Michio Ito, Hachioji, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A novel method and apparatus for electrophotography is disclosed which enables selection the mode of image formation among positive-positive, negative-positive and combinations thereof without any need of changing the polarity of developing toner. The present invention is made on the basis of a known electrophotographic system in which a photosensitive member composed of essentially an electrically conductive substrate, a photoconductive substance layer and an insulating surface layer and which comprises the steps of charging the insulating surface layer, image-wise exposing it to light so as to form a first image almost simultaneously with or some time after the charging step, subjecting it to corona discharge with nearly simultaneous image-wise exposure so as to form a second image and uniformly exposing the whole surface of the photosensitive medium to light so as to form an electrostatic latent image corresponding to a composite image resulting from the first and second images. According to the invention the first and second images to be formed are identical with each other and either one of the two images is selectively exposed to obtain the desired image.