Abstract: An active matrix liquid crystal (LC) display device, comprising in a display area (25) an array of picture elements (12) each having a picture element electrode (15) which together with an opposing common electrode (24) defines an LC display element (21) and a storage capacitor (20) connected to the picture element electrode, includes adjustment means (40,34) for adjusting drive signals applied by a drive circuit (35) to the picture elements (12) in accordance with changes in the LC capacitance. The adjustment means comprises an oscillator circuit (40) which is coupled to at least some of the picture elements in the array and whose oscillation frequency is determined by a capacitance associated with those picture elements and dependent on the capacitances of their LC display elements. The oscillator circuit may be coupled, via switch means (50,61,72), to a storage capacitor line (22) interconnecting the storage capacitor (20) of the picture elements (12) or to the common electrode (24).

Abstract: A matrix display device comprises a row and column array of picture elements (12) each of which consists of a display element (14), e.g. a LC display element, connected in series with a two-terminal non-linear device 15, such as a MIM, between associated row and column address conductors (16,17) to which selection and data signals are applied by a scanning signal drive circuit (20) and a data signal drive circuit (22) respectively, and a reference element circuit (34), comprising a non-linear device (35) in series with a capacitor (36), forming part of a feedback arrangement through which picture element drive voltages are controlled (25) so as to compensate for the effects of aging of the non-linear devices. The reference circuit is driven like the picture elements, with a scanning signal waveform and voltage signal (V.sub.A) applied to opposite sides, and the picture element drive voltages are adjusted in accordance with predetermined changes in the voltage across the capacitor (36).

Abstract: The image contrast in an image display tube having a channel plate electron multiplier (2) is improved by preventing secondary electrons emitted from the face of an input dynode (26) from straying to channels located at a relatively large distance from their origin. This is done by disposing a grid (24) at a short distance from the input dynode (26). If the grid (24) is held at a positive voltage relative to the input dynode (26), stray secondary electrons will be attracted toward the grid (24). Alternatively, if the grid (24) is held at a negative voltage relative to that of the input dynode (26), the secondary electrons will be induced to enter channels close to their origin.

Abstract: A channel plate electron multiplier having channels which rapidly decrease in cross-section away from the input aperture and a conductive structure extending across the input aperture to flatten any fringing electrostatic field, resulting in an electrostatic field configuration which causes secondary emitted electrons to collide with the same side of the channel.