Abstract: A composite photosensitive material for use in electrophotography which comprises a conductive substrate on which there is laminated a first photoconductive layer having a sensitivity to at least a part (Light A) of the chromatic light of visible light region and a second photoconductive layer capable of transmitting said Light A as well as having a sensitivity to another chromatic light (Light B), characterized in that said photoconductive layers are each capable of holding the electric charge of a polarity opposite to each other and additionally accepting as well as retaining a surface potential enough to develop an electrostatic latent image, which is formed by said electric charge, with a toner.

Abstract: A copying method for producing duplicates of an original of at least two colors by using a composite photosensitive member including more than two photosensitive layers, wherein the photosensitive member is subjected to charging more than twice and exposed to an optical image of the original more than once by changing charging and exposing conditions, to vary charge carried on the surface and in the interior of the photosensitive member. This causes two types of electrostatic image to be formed on the surface of the photosensitive member; one type includes image regions having a positive surface potential, a negative surface potential and a substantially zero surface potential respectively and the other type includes two image regions having different surface potentials of same polarity respectively, and one image regions of substantially zero surface potential, depending on differences in color between image regions of the original corresponding to the image regions on the photosensitive member.

Abstract: First and second developing units (66), (67) apply toners of first and second colors respectively to a photoconductive drum (61) carrying a bipolar electrostatic image to form a bicolor toner image. A small amount of the first toner is scraped off the drum (61) in the second developing step and becomes mixed with the second toner in the second developing unit (67). The admixed first toner is separated and removed from the second toner by a separation member in the form of a roller, belt or mesh covered electrode (81) which is charged to a polarity opposite to the first toner and electrostatically attracts the same while repelling the second toner.

Abstract: An electrophotographic development method and apparatus using two magnetic brushes for developing two-color images do not disturb or destroy a first developed image during a second development process, since a second magnetic brush contacts the surface of a latent electrostatic image bearing member more lightly than a first magnetic brush and the toner scraping force of the second magnetic brush is reduced in comparison with that of the second magnetic brush by setting the magnetic flux density on a second non-magnetic sleeve with an internally disposed magnet smaller than the magnetic flux density on a first magnetic sleeve, or by adjusting the distance between the second non-magnetic sleeve and the surface of the latent electrostatic image bearing member or by use of other methods. Further, by employing toners with different quantity of electric charge, high quality two-color images are obtained.

Abstract: Liquid or dry developing substance comprising charged particles is applied to a base electrode in the form of a rotary cylinder. A sheet of recording paper is fed in contact with the cylinder. A printing head comprises a plurality of printing electrode sets formed into an array such as a rectangular dot matrix in which each electrode set constitutes a row of the matrix. Each electrode set comprises a plurality of shaping electrodes which constitute the individual data points of the row. At least one bias electrode is provided for each electrode set. Row select wires are connected to the bias electrodes of the electrode sets respectively. Shaping electrode or column select wires are connected to the shaping electrodes of all of the electrode sets in such a manner that a particular column select wire is connected to the shaping electrodes of all of the electrode sets in a corresponding column.

Abstract: Liquid or dry developing substance comprising charged particles is applied to a base electrode in the form of a rotary cylinder. A sheet of recording paper is fed in contact with the cylinder. A printing head comprises at least one bias electrode to which is applied a bias voltage of a polarity to repel the charged particles against the cylinder. At least one shaping electrode which extends closer to the recording sheet than the bias electrode is selectively applied with a voltage of a polarity and magnitude to overcome the bias voltage and attract only the charged particles immediately adjacent to the shaping electrode to the recording sheet for printing.