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Projection display with intelligent fan Disclosure Number: IPCOM000012699D
Publication Date: 2003-May-21
Document File: 2 page(s) / 54K

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Projection display with intelligent fan

The invention relates to a projection system comprising an illumination system provided with a UHP lamp for generating a light beam, a modulating system for modulating the light beam with image information and a projection lens for projecting the modulated light beam on a screen. The modulation system can be provided with three liquid display panels and analyzers for red, green and blue light channels. Furthermore, the projection system comprises a fan for generating an airflow for cooling of critical components, such as the analyzers, which may not exceed predetermined operating temperatures. In order to reduce the average audible noise level introduced by the rotating fan, the invention proposes to provide the projection system with control means arranged for controlling the rotational speed of the fan in dependence of the image information such that in case the average light load to be absorbed in the analyzer is high, the rotational speed of the fan is high; and in case the average light load to be absorbed in the analyzer is low, the rotational speed is low.

Fig.1 shows a block diagram of a picture analyzing function PAF of a projection system for determining a fan input control signal DV. The subsystem PAF exist of an splitter for splitting an image signal in red, green and blue signals. The splitter is connected to analyzing sub-circuits. The sub-circuits R-brightness, G-brightness and B brightness analyze the red, green and blu...