Projection-type display apparatus with feedback loop for correcting all the defects of the projected image.

摘要

The invention relates to a projection-type display apparatus provided with a feedback chain intended to correct all the defects exhibited by the projected image, these defects resulting both from the projection tubes and from their optics (geometric or focusing defects) and from differences between these tubes (defects of convergence, colorimetry, uniformity of brightness). The feedback chain includes a generator means (6) for a test-card image, a means (3) of recapturing the entire projected image, and means (4) of comparing the signals output by the test image and by the recaptured image; correction signals are formulated from this comparison and are applied to the various control circuits (5) defining the projection characteristics. …The device according to the invention is used also in the real-time tracking of adjustments obtained in a phase prior to the projecting of the sequence of useful video images. …The invention applies in particular to video projectors, to overhead projector display devices or to beam-index tubes. ……