Abstract: The disclosed invention relates to an electro-optical device for use with a facsimile printer, telecopier, etc., designed to accommodate line-at-a-time output of picture information with the aid of an electrically controllable electro-optical substrate. In particular, there is disclosed a solution to the problem of adjusting the electro-optical elements to provide the desired rectilinear output of picture information. The electro-optically active substrate (1) is supported in a frame-like housing (17) such that it may be adjusted perpendicularly relative to a longitudinal edge (18) of the substrate (1) by means of an adjustable ledge (31) and a resilient support (33). A beam of light from a light source (37) is shaped and directed onto the substrate by means of a light-shape converter (36) which can be adjusted relative to the substrate by means of a cross slide arrangement (51, 57) having 2.degree. freedom.

Abstract: Disclosed is a device for measuring the concentration of toner in a developer mixture composed of toner and a ferromagnetic carrier material, e.g., in an electro-photographic developing device. The device comprises a measuring oscillator which comprises an inductance-including component comprising at least one coil wherein the conductor paths of the coil lie substantially in one plane; means for passing at least a portion of the developer mixture into the zone of the inductance; and means for evaluating changes in the frequency of the oscillator resulting from changes in the developer mixture composition passing over the zone of inductance. Also disclosed is an electro-photographic copying apparatus embodying the foregoing device.