A projection device for projecting at least one image onto a projection surface and method therefor

摘要

The invention relates to a projection device for projecting at least one image onto a projection surface, comprising a discharge lamp and a control device for controlling its discharge current (I). In a first drive mode, the discharge current is controlled according to a predeterminable basic current waveform, in a second drive mode the discharge current is controlled according to the magnitude amplitude curve of the basic current waveform without effective commutations, that is in so-called DC phases without changing the current flow direction. The sequence changes between the first activation mode and the second activation mode, the beginning of two consecutive DC phases each differing by a first time interval (tDCInterval) and the DC phase being present during a second time interval (tDCLength). A measuring device determines voltage readings (UMeasured) of the lamp voltage. A control device (40) determines from the difference between a voltage target value (UTarget) and the voltage measurement value, the control deviation (ΔU), a first manipulated variable (OUTControl) and therefrom the first time interval (tDCInterval) and / or the second time interval (tDCLength). The invention further relates to a method for operating such a projection device.