Abstract: An image developing device for use in an electrophotographic copying apparatus or a printer includes a developing roller for supplying toner to a latent image formed on a latent image carrier to develop the latent image into a visible toner image. The image developing device also includes a toner supply roller independently rotatable in abutting engagement with the developing roller for supplying the toner onto the developing roller. Each of the toner supply roller and the developing roller is electrically conductive. An electric potential with its polarity dependent on whether the toner is positively or negatively chargeable is applied between the toner supply toner and the developing roller by a bias voltage distributing circuit.

Abstract: There is disclosed an electron microscope comprising a stage assembly for tilting, translating, or rotating the specimen, a first and a second detector disposed on opposite sides of the optical axis of the beam to detect secondary electrons produced in response to the incidence of the beam. The first detector is disposed relatively close to the optical axis. The second detector is located relatively remotely from the optical axis to prevent the state assembly from colliding against the detector when the assembly is tilted. The gains of the amplifiers to which the outputs of the first and second detectors are applied are made different to compensate for the imbalance between the intensities of the output signals from the detectors.

Abstract: A dual-color electrophotographic copier includes a first photosensitive drum having a first layer comprised of a photoconductive material sensitive to light of a first selected color and a second layer formed on the first layer from a photoconductive material sensitive to light of a second selected color and a second photosensitive drum having a third layer comprised of a photoconductive material sensitive at least to the first selected color. A light image from the same original may be applied to the first and second drums simultaneously to form electrostatic latent images on the first and second drums. These images may be developed by differently colored toner and the toner images may be transferred to the same transfer paper superposingly to obtain a dual-color copy image.