Dynamic contrast and colour

Dynamic contrast and colour

and in the US shortly after. TV line differences will slow introduction to Europe however. Carlo Computer Company Ltd, 38F Shinjuku-Sumitomo Building...

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and in the US shortly after. TV line differences will slow introduction to Europe however.

Carlo Computer Company Ltd, 38F Shinjuku-Sumitomo Building, 261 Ni~hi-Shinjuku, 2~:home, Shin/uku-ku, Tokyo 160, Japan

Lower tilt for a better image A novel liquid crystalalignment technique has been developed by Data Images. The advance is claimed to give more contrast and wider viewing angle to LC multiplexed displays. LC TV for viewing in all I-ights

EL backlights LC TV Unlike other liquid crystal televisions announced recently from Japan (see Displays 4 (1983) 34 and 46 and 2 (1981 ) 301 ), Casio's pocket set can be watched in the dark. It incorporates an electroluminescent panel behind the 120 × 160 twisted nematic LC pixels. It uses a dual matrix drive to address these 19 200 elements with 380 connections to the 41 × 54 mm screen. The overall size of the TV is 80 × 118 mm and 26 mm thick, leading Casio to claim it as the world's smallest. Speaker and power supply are all in'corporated into the one unit. Brightness control of the display is available to allow it to be viewed even in glaring sunlight, Casio claims. Sixteen grey scales are possible. Power consumption is 500 mW normally and 700 mW with the EL backlighting, and the unit receives both UHF and VHF channels. Casio does not see its LC TV market limited solely to consumer use. Businessmen will be able to use it as a data terminal or to receive special information broadcasts. The set is expected to

The contrast ratio-against-viewing angle characteristic of a twisted nematic LCD is non-symmetrical at low voltages. This creates a problem in multiplexed displays resulting in a limited viewing angle, according to Data Images. Its new alignment technique however produces a low tilt - about 2 - 3 ° - unidirectional homogeneous alignment and provides the flexibility for generating a better viewing quadrant. The direction of tilt on top and rear plates is generated to match the sense of the cholesteric imbedded in the LC mixture. This gives rise to the tilt-free viewing angle quadrant. A certain amount of cholesteric is added to the nematic LC mixture to avoid reverse twist. However, the addition of a cholesteric compound reduces the sharpness of the threshold characteristic of the original mixture. The new alignment technique therefore requires the doping of chiral material to be minimized.

TV, video and audio components of Profeel are separatefor greaterflexibility examines the contrast level to maintain the picture within the optimum range. This negates the present day single contrast setting compromise. The result is seen as a new standard of sharpness and definition, says the company. The second technique is known as dynamic colour. The most difficult colours to reproduce on a television screen simultaneously are skin tones and brilliant whites, says Sony. In order to get a brilliant white, the colour temperature has to be very high. However, raising the colour temperature creates unnatural flesh tones.

Dynamic contrast and colour

Dynamic colour circuitry analyses the incoming signals and adjusts the colour temperature, as appropriate, to any particular colour. The net result is an apparent increase in the brightness of whites, whilst retaining realistic colours throughout the colour spectrum. Sony claims that, unlike present televisions, the new set will not be made obsolete by advances in broadcast technology.

Two techniques are claimed to achieve a new standard for domestic television viewing on Sony's Profeel system. First, dynamic contrast continuously

Sony (UK) Ltd, Pyrene House,Sunbury .Cross, Sunbury ~n- Thames, Middx TW16 7A T, UK

Data Images Inc, 1283 A/goma Road, Ottawa, Ontario K I B 3W7, Canada