| 摘要 |
<p>An electro-optical imaging system includes a light source (15), a reference background (11) and a photosensitive device (21) such as a charge coupled array device, an output of which is coupled to a video processor (51 B). Provision is made for self-diagnostic testing. Thus, in a first mode of operation, the light source (15) is off, the output of the photosensitive device being applied to an integrator (59B), to provide an average value over a predetermined time, this value being digitized and applied to a diagnostic processor (57). The output of the video processor (51B) is digitized, and a digital value representing a centre pixel element in a scan is stored in a latch (55B) coupled to the diagnostic processor (57). The diagnostic processor (57) automatically compares the values applied thereto with a set of predetermined voltage values and provides an indication of failure or deteriorating condition according to the result of the comparison. In a second mode of operation, the testing is performed with the light source (15) on.</p> |
