G - Physics – 03 – B
Patent
G - Physics
03
B
350/40
G03B 3/10 (2006.01) H04N 5/232 (2006.01)
Patent
CA 1212459
ABSTRACT This invention provides an automatic focussing apparatus for use in a television camera, having an image pick-up device, a lens and an associated focus setting device. A focus modulating means cyclically modulates a focus setting on an imaging receiving surface of the image pick-up device and a first drive means drives the focus modulating means in response to a signal of a given frequency which is 1/n as large as a frequency of a vertical synchronization signal of a standard television signal, where n is an integer larger than 2. A plurality of band-pass filters having different center frequencies and different reference levels from one another filter a video signal derived from the image pick-up device and a detecting means detects a component of said given frequency from an output of one of the band-pass filters by means of an envelope detection method. A synchronous detecting means obtains a focus control signal including a polarity and an amplitude, by means of a synchronous detection method utilizing said given frequency component and said given frequency and a second driving means controls the focus setting device of the lens in response to the focus control signal. A selecting means determines the focus control signal to be an output signal of one of the band-pass filters which has the highest center frequency among those of the band-pass filters having a larger output than their associated reference level. Since the lens is included in the feedback loop, the accuracy and the stability of the lens itself does not matter. Furthermore, the lens can be made of plastic light weight material.
426858
Kitamura Yoshinori
Nishikawa Shoji
Onishi Masami
Borden Ladner Gervais Llp
Matsushita Electric Industrial Co. Ltd.
LandOfFree
Automatic focussing apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automatic focussing apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic focussing apparatus will most certainly appreciate the feedback.
Profile ID: LFCA-PAI-O-1193462