Patent EP0443818A2 successfully refreshed from Google Patents.
EP0443818A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Auto-focus system for video camera
Assignee: Sony Corp
•
Filing: 1991-02-20
•
Granted: —
•
Expires: 2011-02-20
Abstract
Abstract A focus detection signal is generated from the video signal produced by a video camera even if the scene being imaged is of relatively low contrast or contains areas of high brightness. The autofocussing is performed by deriving higher frequency components of that video signal, detecting when those higher frequency components exceed a minimum threshold level, sensing when the video signal exceeds a maximum threshold, and integrating those higher frequency components which exceed the minimum threshold, except during an interval when the video signal exceeds the maximum threshold, thereby producing the focus detection signal.
Inventors
- 👤 Katsuaki Hirota
- 👤 Akihiro Kikuchi
- 👤 Toshiharu Kondo
- 👤 Takashi Kohashi
- 👤 Fumiaki Kato
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 21:33
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/60; H04N23/67; H04N23/673
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
86 words
A method of generating a focus detection signal from a video signal produced by a video camera, comprising the steps of: deriving higher frequency components of said video signal; detecting signal levels of said higher frequency components which exceed a first minimum threshold to produce a detected signal; sensing when the video signal produced by said video camera exceeds a second maximum threshold; and integrating said detected signal, except during an interval when said video signal exceeds said second threshold, to produce a focus detection signal.
Claim 2
Independent Claim
62 words
A method of generating a focus detection signal from a video signal produced by an image pickup device of a camera, comprising the steps of: deriving higher frequency components of the video signal; detecting signal levels of the higher frequency components which exceed a minimum threshold to produce a detected signal; and integrating the detected signal to provide a focus detection signal.
Claim 3
Independent Claim
57 words
A method of generating a focus detection signal from a video signal produced by an image pickup device of a camera, comprising the steps of: deriving higher frequency components of the video signal; and integrating the higher frequency components except during an interval when the video signal produced by the image pickup device exceeds a maximum threshold.
Claim 4
Dependent Claim
16 words
The method of claim 1, 2 or 3 wherein said video signal comprises a luminance signal.
Claim 5
Dependent Claim
23 words
The method of claim 4 wherein said step of deriving higher frequency components comprises filtering intermediate and higher frequencies of said luminance signal.
Claim 6
Dependent Claim
75 words
The method of claim 5 and claim 1 or 2 wherein said step of detecting signal levels which exceed the minimum threshold comprises establishing said first 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 therein; and subtracting the established first threshold from the level of the filtered intermediate and higher frequencies, thereby producing said detected signal.
Claim 7
Independent Claim
52 words
The method of any one of the preceding claims wherein said step of integrating said detected signal comprises gating said detected signal during fixed periods which define an auto-focus area in a scene being imagined by said video camera to pass said detected signal, and integrating the detected signal which is passed.
Claim 8
Dependent Claim
27 words
The method of claim 7 wherein said step of integrating the detected signal which is passed comprises integrating peak levels of the detected signal which is passed.
Claim 9
Dependent Claim
48 words
The method of claim 7 or 8 and claim 1 or 3 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 10
Dependent Claim
49 words
The method of claim 9 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 second threshold and producing a gate disabling signal for the interval that said luminance signal exceeds said second threshold.
Claim 11
Dependent Claim
83 words
The method of claim 1 or 3 or any one of claims 4 to 10 when appendant to claim 1 or 3 wherein said step of integrating the higher frequency components includes detecting when the video signal produced by the image pickup device exceeds said maximum threshold, defining the interval during which the video signal produced by the image pickup device exceeds said maximum threshold, integrating said higher frequency components, and inhibiting the integration of said higher frequency components during the defined interval.
Claim 12
Dependent Claim
33 words
The method of claim 11 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 13
Dependent Claim
30 words
The method of claim 21 wherein the step of inhibiting the integration of said higher frequency components comprises removing from said video signal the value thereof during the defined interval.
Claim 14
Dependent Claim
94 words
Apparatus for generating a focus detection 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 first minimum threshold to produce a detected signal; sensing means for sensing when the video signal produced by said video camera exceeds a second maximum threshold; and integrating means for integrating said detected signal, except during an interval when said video signal exceeds said second threshold, to produce a focus detection signal.
Claim 15
Dependent Claim
70 words
Apparatus for generating a focus detecting signal from a digital video signal produced by an image pickup device of a camera, comprising: digital filter means for deriving higher frequency components of the digital video signal; detecting means for detecting signal levels of the higher frequency components which exceed a minimum threshold to produce a detected signal; and integrating means for integrating the detected signal to provide a focus detection signal.
Claim 16
Dependent Claim
63 words
Apparatus for generating a focus detection signal from a digital video signal produced by an image pickup device of a camera, comprising: digital filter means for deriving higher frequency components of the video signal; and integrating means for integrating the higher frequency components except during an interval when the digital video signal produced by the image pickup device exceeds a maximum threshold value.
Claim 17
Dependent Claim
16 words
The apparatus of claim 14, 15 or 16 wherein said video signal comprises a luminance signal.
Claim 18
Dependent Claim
25 words
The apparatus of claim 17 wherein the filter means is coupled to receive said luminance signal and to separate intermediate and higher frequency components therefrom.
Claim 19
Dependent Claim
71 words
The apparatus of claim 17 or 18 wherein said detecting means comprises threshold means for establishing the or a 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 first threshold from the higher frequency components of the video signal, thereby producing said detected signal.
Claim 20
Independent Claim
47 words
The apparatus of any one of claims 14 to 19 wherein said integrating means includes gating means for gating said detected signal during fixed periods which define an auto-focus area in a scene being imaged by said video camera, and means for integrating the gated detected signal.
Claim 21
Dependent Claim
29 words
The apparatus of claim 20 wherein said integrating means further comprises disabling means for disabling the gating means during said interval when said video signal exceeds said second threshold.
Claim 22
Dependent Claim
49 words
The apparatus of claim 21 wherein said sensing means comprises comparator means for comparing said luminance signal to said second 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 second threshold.
Claim 23
Independent Claim
28 words
The apparatus of any one of claims 14 to 22 wherein said means for integrating comprises peak integrating means for integrating peak levels of the gated detected signal.
Claim 24
Dependent Claim
91 words
The apparatus of claim 14 or 16 or any one of claims 17 to 23 when appendant to claim 14 or 16 wherein said integrating means includes detecting means for detecting when the digital video signal produced by the image pickup device exceeds said maximum threshold value, means for defining an interval during which the digital video signal produced by the image pickup device exceeds said maximum threshold value, means for integrating said higher frequency components, and for inhibiting the means for integrating said higher frequency components during the defined intervals.
Claim 25
Dependent Claim
30 words
The apparatus of claim 24 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 26
Dependent Claim
28 words
The apparatus of claim 24 or 25 wherein said means for inhibiting comprises means for removing from said digital video signal the value thereof during the defined interval.
Claim 27
Dependent Claim
121 words
Apparatus for controlling the optical focus 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; and selection means for selecting from said filter means filter characteristics having narrower spectral characteristics as said lens means approaches said just-focused condition.
Claim 28
Dependent Claim
37 words
The apparatus of claim 27 wherein said selection means includes sense means for sensing said focus detection signal and for selecting a filter characteristic having a narrower spectral characteristic in response to said sensed focus detection signal.
Claim 29
Dependent Claim
48 words
The apparatus of claim 28 wherein said sense means senses the rate at which said focus detection signal changes, and further includes 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.
Claim 30
Dependent Claim
70 words
The apparatus of claim 27, 28 or 29 wherein said filter means includes plural filter processor means, each having a respective spectral characteristic; and said selection means comprises coupling means for coupling an individual one of said filter processor means to said 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.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.