Brightness sensor for a display device of a motor vehicle

The invention features a first and a second light sensor (4, 5), which signals are fed into an evaluating processor unit (3). Depending on the output signal of the evaluating processor unit (3) the brightness control unit (6) adjusts the brightness of the display unit (1) in such a way that the display is optimally readable. The first light sensor (4) measures the ambient light and the second light sensor (5) the light directed towards the display unit (1).