Abstract: A display system for displaying a visual image in response to a video signal (10,34), comprising; a liquid crystal display panel (1) divided into a plurality of addressable, variable brightness sections (5); address circuit (6) for generating a section address corresponding to a section in response to a timing signal (11); driver circuit (7,8) for varying the brightness of the section in response to a brightness signal (14,15) derived from the video signal (10,34); characterised in that the display system further comprises: a memory (36) for storing a predetermined correction signal (35) corresponding to the section; and control circuit (31) coupled to the driver circuit (7,8) for varying the brightness signal (14,15) to reduce brightness non-uniformities in the displayed image in response to the video signal (34) and the correction signal (35) in combination.

Abstract: An input device for a visual display comprising a light source and a scanner for angularly scanning a light beam from the light source across a plane. A photodetector detects interruption of the beam by an article positioned in the plane. The scanner comprises a shutter having a linear array of addressable, electrically actuable shutter elements. Each element is operable to transmit or block light from the light source under the control of a corresponding electrical signal. Because the light beam is scanned by a shutter rather than a mechanical scanner, the device is advantageously more reliable than conventional electromechanical optical input devices.

Abstract: A field emission display comprises a screen (10) divided into a plurality of pixels. Each pixel has a plurality of subpixels (130,140,150) of different phosphor efficacies. A matrix of field emission cathodes (80) is directed towards corresponding pixels of the screen (10). Each cathode has a plurality of arrays (81,82,83) of field emissive tips directed towards corresponding subpixels (130,140,150). The arrays of each cathode (80) comprise different numbers of field emission tips to reduce the effect of the difference in the phosphor efficacies of the corresponding subpixels (130,140,150). This advantageously permits tracking between the primary colour components of a gray scale displayed image to be maintained used the same algorithm to translate into voltages for driving the arrays. Therefore, the Colour Point or White Point of the display can be maintained between extremes of gray scale using the same algorithm.