Auto-focus system for video camera

Claim 3

The method of claim 1 wherein said video signal comprises a luminance signal.

Claim 4

The method of claim 2 wherein said step of deriving higher frequency components comprises filtering intermediate and higher frequencies of said luminance signal.

Claim 9

The method of claim 5 wherein said step of integrating the detected signal which is passed comprises integrating peak levels of the detected signal which is passed.

Claim 10

The method of claim 5 wherein said step of integrating said detected signal further comprises disabling the gating of said detected signal during said interval when said video signal exceeds said maximum threshold, thereby blocking the passage of said detected signal.

Claim 11

The method of claim 7 wherein the step of sensing when the video signal produced by said video camera exceeds said maximum threshold comprises comparing said luminance signal to said maximum threshold and producing a gate disabling signal for the interval that said luminance signal exceeds said maximum threshold.

Claim 16

The method of claim 10 wherein said step of integrating the detected signal which is passed comprises integrating peak levels of the detected signal which is passed.

Claim 19

The method of claim 12 wherein said step of integrating the higher frequency components which are passed comprises integrating peak levels of the higher frequency components which are passed.

Claim 20

The method of claim 12 wherein said step of integrating further comprises disabling the gating of said higher frequency components during said interval when said video signal exceeds said maximum threshold, thereby blocking the passage of said higher frequency components.

Claim 23

The method of claim 15 wherein the step of inhibiting the integration of said higher frequency components comprises blocking said higher frequency components from being supplied to integrating means during the defined interval.

Claim 24

Apparatus for generating a focus detections signal from a video signal produced by a video camera, comprising: filter means for deriving higher frequency components of said video signal; detecting means for detecting signal levels of said higher frequency components which exceed a minimum threshold to produce a detected signal; sensing means for sensing when the video signal produced by said video camera exceeds a maximum threshold; integrating means for integrating said detected signal; and means for inhibiting said integrating when said video signal exceeds said maximum threshold, to produce a focus detection signal.

Claim 25

Apparatus for generating a focus detections signal from a video signal produced by a video camera, comprising: filter means for deriving higher frequency components of said video signal; detecting means for detecting signal levels of said higher frequency components which exceed a minimum threshold to produce a detected signal; sensing means for sensing when the video signal produced by said video camera exceeds a maximum threshold; integrating means for integrating said detected signal; and means for inhibiting said integrating when said video signal exceeds said maximum threshold, to produce a focus detection signal.

Claim 26

The apparatus of claim 17 wherein said video signal comprises a luminance signal.

Claim 27

The apparatus of claim 18 wherein said detecting means comprises threshold means for establishing said minimum threshold at a level greater than an expected noise signal level included in said luminance signal when said video camera images a scene with relatively little contrast changes therein; and means for subtracting the established minimum threshold from the higher frequency components of the video signal, thereby producing said detected signal.

Claim 30

The apparatus of claim 20 wherein said means for integrating comprises peak integrating means for integrating peak levels of the gated detected signal.

Claim 31

The apparatus of claim 20 further comprising disabling means for disabling the gating means during said interval when said video signal exceeds said maximum threshold.

Claim 32

The apparatus of claim 22 wherein said sensing means comprises comparator means for comparing said luminance signal to said maximum threshold to produce a gate disabling signal and to supply said gate disabling signal to said disabling means for the interval that said luminance signal exceeds said maximum threshold.

Claim 37

The apparatus of claim 25 wherein said means for integrating comprises peak integrating means for integrating peak levels of the gated detected signal.

Claim 40

The apparatus of claim 27 wherein said means for integrating comprises peak integrating means for integrating peak levels of the gated intermediate and higher frequency components.

Claim 41

The apparatus of claim 27 wherein said integrating means further comprises disabling means for disabling the gating means during said interval when said video signal exceeds said maximum threshold.

Claim 44

The apparatus of claim 30 wherein said means for inhibiting comprises means for blocking said higher frequency components from being supplied to said means for integrating during the defined interval.

Claim 45

Apparatus for controlling the optical focusing of adjustable lens means in a video camera, comprising: filter means exhibiting plural filter characteristics ranging from relatively broad to relatively narrow spectral characteristics, for deriving higher frequency components of a video signal produced by said video camera; focus detection means coupled to said filter means for generating a focus detection signal from the higher frequency components derived by said filter means, said focus detection signal representing the focus condition of said lens means; lens drive means responsive to said focus detection signal for driving said lens means toward a just-focused condition; sense means for sensing the rate at which said focus detection signal changes and generating a sensed focus detection signal, means for detecting when the rate of change of said focus detection signal is too slow for selecting a filter characteristic having a narrower spectral characteristic; and selection means for selecting from said filter means a filter characteristic having a narrower spectral characteristic as said lens means approaches said just-focused condition in response to said sensed focus detection signal.

Claim 46

Apparatus for controlling the optical focusing of adjustable lens means in a video camera, comprising: filter means exhibiting plural filter characteristics ranging from relatively broad to relatively narrow spectral characteristics, for deriving higher frequency components of a video signal produced by said video camera; focus detection means coupled to said filter means for generating a focus detection signal from the higher frequency components derived by said filter means, said focus detection signal representing the focus condition of said lens means; lens drive means responsive to said focus detection signal for driving said lens means toward a just-focused condition; sense means for sensing the rate at which said focus detection signal changes and generating a sensed focus detection signal, means for detecting when the rate of change of said focus detection signal is too slow for selecting a filter characteristic having a narrower spectral characteristic; and selection means for selecting from said filter means a filter characteristic having a narrower spectral characteristic as said lens means approaches said just-focused condition in response to said sensed focus detection signal.

Claim 47

Apparatus for controlling the optical focusing of adjustable lens means in a video camera, comprising: filter means including plural filter processor means, each having a respective spectral characteristic ranging from a relatively broad to a relatively narrow spectral characteristic, for deriving higher frequency components of a video signal produced by said video camera; focus detection means coupled to said filter means for generating a focus detection signal from the higher frequency components derived by said filter means, said focus detection signal representing the focus condition of said lens means; lens drive means responsive to said focus detection signal for driving said lens means toward a just-focused condition; and selection means for selecting from said filter means filter characteristics having narrower spectral characteristics as said lens means approaches said just-focused condition and comprising coupling means for coupling an individual one of said filter processor means to said focus detection means, means for sensing a rate of change in the focus detection signal level, and means for determining when the rate of change is too low to couple a different filter processor means to said focus detection means.

Claim 48

Apparatus for controlling the optical focusing of adjustable lens means in a video camera, comprising: filter means including plural filter processor means, each having a respective spectral characteristic ranging from a relatively broad to a relatively narrow spectral characteristic, for deriving higher frequency components of a video signal produced by said video camera; focus detection means coupled to said filter means for generating a focus detection signal from the higher frequency components derived by said filter means, said focus detection signal representing the focus condition of said lens means; lens drive means responsive to said focus detection signal for driving said lens means toward a just-focused condition; and selection means for selecting from said filter means filter characteristics having narrower spectral characteristics as said lens means approaches said just-focused condition and comprising coupling means for coupling an individual one of said filter processor means to said focus detection means, means for sensing a rate of change in the focus detection signal level, and means for determining when the rate of change is too low to couple a different filter processor means to said focus detection means.