| 摘要 |
PCT No. PCT/SE88/00397 Sec. 371 Date Feb. 5, 1991 Sec. 102(e) Date Feb. 5, 1991 PCT Filed Aug. 5, 1988 PCT Pub. No. WO90/01725 PCT Pub. Date Feb. 22, 1990.The present invention relates to a method and apparatus for carrying out the focusing of projected images. To carry out such focusing, an image sensor operates on a small section of the projected image to blow it up to a point where only the grains of the image become larger than the resolution of the sensor. The image set obtained is electronically scanned so that a signal is received which includes a low frequency band determined by the grain density and a harmonic span generated by the transitions between grains and interstices, whereby a differential voltage is created which is indicative of the state of focusing.
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