Abstract: In an automatic focusing device for an imaging apparatus, a band-pass filter separates high frequency components from a luminance signal. A window processing section extracts a part of the output of the band-pass filter which lies in a predetermined focus area. In a slice circuit, a first and a second high level priority circuit slice respectively positive components and negative components, which constitute the extracted signal, on the basis of a reference voltage generated by a reference voltage source. A differential amplifier amplifies a difference between the outputs of the two high level priority circuits. An absolute value circuit regulates the amplified signal to a predetermined polarity. A peak hold circuit transforms the output of the absolute value circuit to a sampled peak value signal. An integrating circuit integrates the peak values of the peak value signals every predetermined period of time so as to calculate an evaluation value for focusing.

Abstract: An image quality correction circuit for use with an imaging apparatus which converts a luminance signal so that an intermediate portion of the signal between preset minimum and maximum values is extended. The invention also relates to a device where color difference signals are corrected in accordance with the same nonlinear characteristic utilized in the correction of the luminance signal.

Abstract: An image forming apparatus with a binding function wherein small bands of toner are deposited on paper sheets, a plurality of said sheets are then stacked and thereafter said small bands of deposited toner are fused, thereby binding said sheets.In order to form said small bands of toner on an electrostatic latent image carrier, the present invention is provided with a charger disposed between an exposure position and the developing position so as to be movable perpendicularly to the paper transport direction, an optical shutter disposed in the image exposure optical path and selectably operable, or a scale disposed at one side of a platen glass for preventing light from reaching the image carrier.Said small band of toner formed on the image carrier may be developed by a special toner such as waste toner removed from the surface of the image carrier after being supplied to copy the original document image, white toner, color toner, or highly self-adhesive toner.

Abstract: Arsenic anhydride of high purity is inexpensively manufactured from an arsenic sulfide-containing substance by first contacting the arsenic sulfide-containing substance with a copper sulfate-containing aqueous solution so as to provide an extract solution containing arsenious acid, the extract solution is subjected to aeration in the presence of copper ions such that the arsenious acid therein is mostly oxidized to arsenic acid, the thus provided treated solution is subjected to a weak reducing agent to cause crystals of arsenious anhydride to form, and these crystals are then recovered.