Automatisches Fokussierungssystem für Videokamera

Système de mise au point automatique pour caméra vidéo

Auto-focus system for video camera


A focus control apparatus for controlling the optical focus of adjustable lens means 1 in a video camera, comprising: filter means 35-38 exhibiting a plurality of different filter characteristics which, relative to one another, range from having relatively broad to relatively narrow spectral characteristics, for deriving higher frequency components of a video signal produced by said video camera; focus detection means 40-45 coupled to said filter means 35-38 for generating a focus detection signal from higher frequency components derived by said filter means 35-38, said focus detection signal representing the focus condition of said lens means 1; lens drive means 3 responsive to said focus detection signal for driving said lens means 1 toward a just-focused condition; and selection means 12, 39 for selecting from said filter means filter characteristics having successively narrower spectral characteristics as said lens means approaches said just-focused condition, characterised in that: said focus control apparatus further comprises a focus area setting means 24 for setting one of a plurality of focus areas AE 1 , AE 2 of a scene being imaged by said video camera, and said focus detection means generates said focus detection signal from higher frequency components from within the focus area which has been set; and said focus area setting means initially sets a first focus area AE 2 when said selection means (12, 39) selects a first filter characteristic, and subsequently sets a different focus area AE 1 as the lens approaches said just-focused condition and said selection means 12, 39 selects filter characteristic having successively narrower spectral characteristics.




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Cited By (2)

    Publication numberPublication dateAssigneeTitle
    EP-0924544-A2June 23, 1999Samsung Electronics Co., Ltd.Auto-focusing apparatus and method
    EP-0924544-A3April 26, 2000Samsung Electronics Co., Ltd.Appareil autofocus et méthode