Abstract: A stationary screen (14) of cylindrical or frusto-conical form is mounted inside the downstream end sifting section (10B) of a machine housing (10) which also has an upstream end feed section (10A). An auger screw (24) is provided in the upstream end section (10A) on a shaft (20) which is rotatable so as to feed material to be sifted into an end of the screen (14). The shaft (20) is mounted in cantilever manner from the upstream end of the housing (10) and drive means are mounted at or near the upstream end of the housing to rotate the shaft (20). A paddle assembly (26) is provided in the downstream end section (10B), inside the screen (14), and is mounted to the same shaft (20) as the auger screw (24). This shaft (20) is a hollow shaft. A second rotatable shaft (30) extends, preferably co-axially, through the first hollow shaft (20) and projects beyond the first hollow shaft into the screen (14).

Abstract: A display comprises a display device having an image output surface at which an image is displayed as a spaced array of pixel elements, a light transmitting element in the form of an image guide having a viewing surface, the light transmitting element arranged to receive light from the display device and display the received light on the viewing surface, the light transmitting element having a polarising layer arranged in an optical path between the display device and the viewing surface, wherein the polarising layer is arranged to attenuate unpolarised ambient light received from outside the display while substantially transmitting polarised light received from the display device.

Abstract: An image display comprises an image display device for generating a viewable image; and an optical angular selector for selecting an angular range of light to form the viewable image, the optical angular selector having an array of substantially parallel light transmission guides each comprising a light-guiding region to promote propagation of light incident upon the light-guiding region within a range of angles of incidence by refraction and/or total internal reflection and an absorbing material peripherally arranged with respect to the light-guiding region to absorb light incident upon the light-guiding region outside the range of angles of incidence.

Abstract: An image display comprises: a display device having an image output surface at which an image is displayed as a spaced array of pixel elements; an image guide (20) coupled to the image output surface of the display device and comprising a plurality of light transmission guides (80) each having an input end and an output end, the input ends of the light transmission guides being arranged relative to one another so that groups of one or more light transmission guides receive light from respective groups of one or for a cluster comprising at least a subset of the light transmission guides (80): at the outer periphery of the cluster, the input ends of the light transmission guides are constrained against expansion by a frame formed of a material having thermal expansion properties which are substantially similar to the thermal expansion properties of the image output surface.

Abstract: An image display comprises an image display device having an array of electrically driven picture elements (60) viewable at a viewing surface (90); and luminance correction means (110) arranged with respect to the image display device so as to apply a spatial luminance filter (122, 124) to the output of the image display device, the spatial luminance filter attenuating the light output by each picture element of the image display device in substantially inverse relation to the luminance response characteristics of the picture element so that each picture element exhibits substantially the same luminance for a given input electrical driving signal.

Abstract: A photoluminescent liquid-crystal display includes a liquid crystal (31) sandwiched between two transparent substrates (1, 21) for modulating input light, control electrodes (13, 23) for controlling the liquid crystal, and display output means incorporating a photoluminescent material (3) such as a phosphor for producing a visible image from the input light modulated by the liquid crystal. The phosphor is at the inner face (16) of the front substrate (1) but is sepraated from the liquid-crystal by a thin transparent auxiliary substrate (7) having a thickness of less than about 300 &mgr;m. This allows the phosphors to be close to the liquid-crystal layer (31), minimising crosstalk, without interfering with the electro-optic properties of the device.

Abstract: A collimator is formed of a stack of layers (11) of different thicknesses in a way analogous to a low-pass interference filter. When illuminated by narrow-band light of a predetermined wavelength just within the pass band of the filter, the collimator preferentially transmits light incident within a predetermined angular range, usually near-normal. The collimator is especially useful with photoluminescent liquid-crystal display, having phosphor emitters (17), because the collimator layers can simply be deposited on one face of the liquid-crystal modulator (1).