IMPROVEMENTS IN OR RELATING TO A DISPLAY APPARATUS

摘要

A display apparatus (20) includes an electromagnetic radiation source (22) and digital micro-mirror device (21) having a plurality of micro-mirror elements on a surface thereof. The electromagnetic radiation source (22) is arranged to illuminate the digital micro-mirror device (21) and at least one micro-mirror element of the digital micro-mirror device (21) either reflects electromagnetic radiation along a primary path (23) to an exit lens (23) to form a desired image to be viewed by an operator or along a secondary path (25) to an electromagnetic radiation dump (26). The digital micro-mirror device (21) is also operable to generate a test image at the electromagnetic radiation dump (26) at a predetermined time. An electromagnetic radiation measurement arrangement (27) is arranged along the secondary path (25), between the digital micro-mirror device (21) and the radiation dump (26), to measures a luminance value of electromagnetic radiation representing the test image reflected by the digital micro-mirror device (21) and an associated comparator processor compares the measured luminance with an ideal luminance for the test image.