| 摘要 |
<p>A projection display comprises a display device (CRT) forming an image (M) for projection onto a display screen (700). A photo sensor (S) is adjacent to the display screen (700) and generates a first signal (Isen) responsive to a level of the projected image (M) illumination incident on the photo sensor (S). A detector (275) is coupled to receive the first signal (Isen) and generates an output signal (202) indicative of detecting the first signal (Isen). A source (Q2/D) of a predetermined detection threshold value (Iref) is coupled to the detector (275) for determining a threshold at which the detection of the first signal (Isen) occurs. Wherein the first signal (Isen) exceeds the predetermined detection threshold value (Iref), the detector (275) detects and generates the output signal (202) indicative of signal detection, and generates a second signal (Vlit) for coupling to the source (Q2/D) to change the predetermined detection threshold value (Iref). <IMAGE></p> |
