Projection system

Abstract

A projection system for image reproduction by means of at least one lamp (10) as well as a sensor (30;301,302,303) for generating a sensor signal for monitoring changes in the luminous flux generated by said at least one lamp (10) and for compensating these changes through a suitable control of the image reproduction is described. The projection system comprises a device (31; 32; 36; 37) for eliminating substantially periodic interference components from the sensor signal generated by the at least one sensor (30; 301, 302, 303). These interference components may be generated by an optical component such as in particular a color modulator (12) of the projection system. The invention thus renders possible an at least substantially interference-free compensation of fluctuations in the luminous flux generated by the lamp (10), for example owing to an unstable arc discharge, also in those color systems in which the positioning of the sensor (30) in the projection system is non-critical.

Description

technical field

[0001] The invention relates to a projection system for image reproduction by means of at least one lamp and a sensor for generating a sensing signal monitoring changes in the luminous flux produced by said at least one lamp and for appropriate control by means of image reproduction compensate for these changes. Background technique

[0002] The light source used in a projection system is usually formed by one or several high pressure gas discharge lamps (HID [High Intensity Discharge] lamps or UHP [Ultra High Performance] lamps). These lamps can in principle be operated with both direct current and alternating current. Both modes of operation have their advantages and disadvantages. AC operation prevents rapid corrosion of the electrodes and can increase the luminous efficacy of the lamp, but arc discharges are generally unstable due to polarity changes, allowing periodic brightness fluctuations or other image disturbances. However, neither of them can be...

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