Abstract: A portable collapsible liquid crystal display apparatus which includes a base, and a relatively large viewing screen having a width corresponding substantially to the overall width of said base and which, together with a first planar member of the same size, are pivotally mounted on the base. When the apparatus is in its viewing mode, the screen is turned to an upright position on the base with the mirror in an inclined position extending downwardly behind the screen to reflect images over the entire rear surface of the screen. When the unit is in a collapsed mode, the screen is folded down over the base and the mirror is folded down on top of the screen with its reflective surface facing the screen and with its rear surface forming a protective cover for the screen. The linkage mechanism which couples the screen and mirror to the base includes relatively wide links which also serve to shield the rear surface of the screen from ambient light when the screen is in its upright viewing position.

Abstract: A power supply for an incandescent lamp by which sufficient power is supplied to the lamp to enable the lamp to reach its desired color temperature without exceeding the break over voltage of its filament even though the peaks of the alternating current voltage applied to the power supply exceed the break-over voltage of the filament of the lamp. This is achieved in a preferred embodiment by full-wave rectification of the alternating current voltage applied to the power supply to produced an unfiltered voltage comprising a series of half-cycle sine waves of a particular polarity. This voltage is applied to the lamp. However, when the voltage of each half cycle is above the breakover voltage of the lamp, the lamp is switched out of the circuit, so that only those portions at the beginning and end of each half cycle which are below a particular voltage are actually applied to the lamp.

Abstract: A projection system comprising a liquid crystal light valve having a wider acceptance angle for incident light in a first direction than in a second direction transverse to the first direction and an illumination system. The illumination system provides light to the liquid crystal light valve at a greater beam spread angle in the first direction than in the second direction. The system also includes projection optics for receiving light from the liquid crystal light valve and projecting such light toward a projection surface.