Abstract: Nematic liquid crystal display device, in which the isocontrast curve has obtained a more symmetrical shape by combining two and four sub-pixels with twist angles which are smaller than 90 degrees, at which the sub-pixels are obtained by providing different orientation directions (11) in an orienting layer (8) by means of linearly polarized light. If a cholesteric nematic liquid crystal material is used, a sub-pixel may have a twist angle of more than 90 degrees, while pairs of sub-pixels then have twist angles of opposite twist sense, at which the sum of the absolute values of the twist angles is smaller than 180 degrees.

Abstract: A circuit arrangement for the square-wave modulated high-frequency voltage operation of a discharge lamp, including means to control the duty cycle of the square wave, has a measuring circuit for detecting the ignition of the discharge lamp during each cycle of the substantially square-wave modulation and a timer circuit coupled to the measuring circuit for rendering the amplitude of the high-frequency voltage substantially equal to zero when a time interval has elapsed after the ignition of the discharge lamp, whereby the luminous flux of the discharge lamp fluctuates to a low degree only.