Patent ID: 6979085

Claim:
An image projector ( 100 ) with: an optical system ( 110 ), comprising a High-Intensity-Discharge HID lamp ( 112 ), in particular an Ultra High Pressure UHP lamp, and arranged after this a display field ( 114 ) and a lens unit ( 116 ) for projecting an image prepared on the display field ( 114 ) through the lens unit ( 116 ) onto a picture screen device ( 118 ); a lamp driver ( 131 ) for providing a supply voltage to the HID lamp; and an image processor ( 120 ) for providing the image for the display field ( 114 ); characterized by a sensor device ( 140 ) for detecting the brightness, in particular the brightness distribution and/or the overall brightness, of the light incident on the display field ( 114 ) at various times; a comparator device ( 150 ) for comparing the brightness of the light detected by the sensor device ( 140 ) at a previous moment t- 2 and a moment t- 1 , which is later in time than moment t- 2 , and for generating a brightness control signal which represents a change in brightness caused by an arc jump that occurred in the HID lamp ( 112 ) between the moments t- 2 and t- 1 ; and a control device ( 113 , 120 ′, 132 ) for compensating the detected change in brightness in response to the brightness control signal by resetting the brightness of the light incident on the picture screen device ( 118 ) at a moment t 0 later than t- 1 , in particular to the brightness detected at the previous moment t- 2 , and by subsequent conversion of the reset brightness during a predetermined time interval T to the brightness detected at the later moment t- 1 , the resetting of the brightness occurring so soon after the arc jump, and the conversion of the brightness during the time interval T occurring so slowly that the changes in the brightness of the light incident on the picture screen device ( 118 ) caused by the arc jump, the reset, and the conversion are not perceptible to the human eye.