EP0390091A2
Expired / Lapsed
EP
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Automatic focus adjusting device
Assignee: Canon Inc
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Filing: 1990-03-27
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Granted: —
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Expires: 2010-03-27
Abstract
Abstract An automatic focus adjusting device comprises an image sensor arranged to convert into a video signal an object image formed on its image sensing plane by a photo-taking lens optical system and to produce the video signal; a circuit which detects a high-frequency component included in the video signal; a circuit which detects from the video signal the degree of sharpness of the image on the basis of the width of the edge part of the image; a driving circuit which changes the position of the optical system relative to the image sensing plane in the direction in which the detection output of the high-frequency component and that of the degree of sharpness increase; and a control circuit which controls the driving speed of the driving circuit according to the detection output of the degree of sharpness.
Inventors
- 👤 Kunihiko Yamada
- 👤 Akihiro Fujiwara
- 👤 Hirofumi Suda
- 👤 Masamichi Toyama
- 👤 Kitahiro Kaneda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 10:05
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/36; G02B7/365; H; H04; H04N; H04N23/00; H04N23/60; H04N23/67; H04N23/673; H04N23/95; H04N23/958; H04N23/959
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
138 words
An automatic focus adjusting device comprising: a) image sensing means for an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) first detecting means for detecting a predetermined high-frequency component from the video signal; c) second detecting means for detecting, from the video signal, a signal corresponding to the sharpness of an edge part of object image; d) driving means for varying the position of said photo-taking lens optical system relative to said image sensing plane in the direction in which said high-frequency component and an output level of said signal corresponding to the sharpness of the edge part increase; and e) control means for controlling the driving speed of said driving means according to the level of said signal corresponding to the sharpness of the edge part.
Claim 2
Dependent Claim
138 words
An automatic focus adjusting device comprising: a) image sensing means for an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) first detecting means for detecting a predetermined high-frequency component from the video signal; c) second detecting means for detecting, from the video signal, a signal corresponding to the sharpness of an edge part of object image; d) driving means for varying the position of said photo-taking lens optical system relative to said image sensing plane in the direction in which said high-frequency component and an output level of said signal corresponding to the sharpness of the edge part increase; and e) control means for controlling the driving speed of said driving means according to the level of said signal corresponding to the sharpness of the edge part.
Claim 3
Dependent Claim
26 words
A device according to claim 1, wherein said second detecting means is arranged to detect a signal related to the edge width of said edge part.
Claim 4
Dependent Claim
28 words
A device according to claim 2, wherein said signal related to said edge width is a normalized signal which is unaffected by the contrast of the object image.
Claim 5
Dependent Claim
48 words
A device according to claim 1, wherein said driving means is arranged to drive said photo-taking lens optical system; and said control means is arranged to change the driving speed of said driving means by a plurality of steps according to an output of said second detecting means.
Claim 6
Dependent Claim
48 words
A device according to claim 1, wherein said control means is arranged to change said driving speed at least by three steps in such a way as to have the lowest speed when the focus position of said optical system is in the neighborhood of an in-focus point.
Claim 7
Dependent Claim
149 words
An automatic focus adjusting device comprising: a) image sensing means for converting an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) first detecting means for detecting, from the video signal, a first focus signal which corresponds to a high-frequency component of the video signal; c) second detecting means for detecting, from the video signal, a second focus signal which represents the sharpness of an edge part of the object image; d) driving means for varying the position of said photo-taking lens optical system relative to said image sensing plane in the direction in which output levels of said first and second focus signals increase; and e) control means for controlling the driving speed of said driving means according to the output level of said second focus signal and the depth of field of said photo-taking lens optical system.
Claim 8
Dependent Claim
149 words
An automatic focus adjusting device comprising: a) image sensing means for converting an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) first detecting means for detecting, from the video signal, a first focus signal which corresponds to a high-frequency component of the video signal; c) second detecting means for detecting, from the video signal, a second focus signal which represents the sharpness of an edge part of the object image; d) driving means for varying the position of said photo-taking lens optical system relative to said image sensing plane in the direction in which output levels of said first and second focus signals increase; and e) control means for controlling the driving speed of said driving means according to the output level of said second focus signal and the depth of field of said photo-taking lens optical system.
Claim 9
Dependent Claim
26 words
A device according to claim 6, wherein said control means is arranged to change the driving speed of said driving means at least by three steps.
Claim 10
Dependent Claim
43 words
A device according to claim 6, wherein said control means is arranged to change, according to the depth of field, threshold values set to be used in changing and determining said driving speed according to the output level of said second focus signal.
Claim 11
Dependent Claim
60 words
A device according to claim 8, wherein said control means is arranged to change said speed changing threshold values, in such a way as to keep the driving speed change-over position of said photo-taking lens optical system unvarying relative to an in-focus point, in accordance with the shape of a focusing characteristic curve which varies with the depth of field.
Claim 12
Dependent Claim
66 words
An automatic focus adjusting device comprising: a) detecting means for detecting, from a video signal, a signal corresponding to a focused condition; b) speed control means for changing a focus adjusting speed by comparing an output of said detecting means with a predetermined threshold value; and c) means for varying said threshold value used for changing said focus adjusting speed according to the depth of field.
Claim 13
Dependent Claim
66 words
An automatic focus adjusting device comprising: a) detecting means for detecting, from a video signal, a signal corresponding to a focused condition; b) speed control means for changing a focus adjusting speed by comparing an output of said detecting means with a predetermined threshold value; and c) means for varying said threshold value used for changing said focus adjusting speed according to the depth of field.
Claim 14
Dependent Claim
24 words
A device according to claim 10, wherein said speed control means is arranged to control said focus adjusting speed at least in three steps.
Claim 15
Dependent Claim
28 words
A device according to claim 10, wherein said signal corresponding to the focused condition is related to the edge width of an edge part of an object image.
Claim 16
Dependent Claim
19 words
A device according to claim 12, wherein said signal related to the edge width is normalized relative to luminance.
Claim 17
Dependent Claim
125 words
An automatic focus adjusting device comprising: a) image sensing means for converting an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) focus detecting means for detecting from the video signal a predetermined signal component which corresponds to a focused condition; c) high-luminance detecting means for detecting a high-luminance part of said image sensing plane; d) driving means for varying the position of said photo-taking lens optical system relative to said image sensing plane according to an output of said focus detecting means; and e) control means for controlling and changing the driving speed of said driving means according to an output of said focus detecting means and an output of said high-luminance detecting means.
Claim 18
Dependent Claim
125 words
An automatic focus adjusting device comprising: a) image sensing means for converting an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) focus detecting means for detecting from the video signal a predetermined signal component which corresponds to a focused condition; c) high-luminance detecting means for detecting a high-luminance part of said image sensing plane; d) driving means for varying the position of said photo-taking lens optical system relative to said image sensing plane according to an output of said focus detecting means; and e) control means for controlling and changing the driving speed of said driving means according to an output of said focus detecting means and an output of said high-luminance detecting means.
Claim 19
Dependent Claim
61 words
A device according to claim 14, wherein said control means is arranged to compare the level of the output of said focus detecting means with a predetermined threshold value, to select the driving speed of said driving means according to the result of comparison and to vary said speed changing threshold value according to the output of said high-luminance detecting means.
Claim 20
Dependent Claim
55 words
A device according to claim 15, wherein said control means is arranged to vary said threshold value in such a way as to keep the driving speed change-over positions of said driving means unvarying relative to an in-focus point when the shape of a focusing characteristic curve is changed by a high degree of luminance.
Claim 21
Dependent Claim
71 words
A device according to claim 14, wherein said focus detecting means includes a first detecting means for detecting a high-frequency component of the video signal and a second detecting means for detecting information on the width of an edge part of the object image, and wherein said control means is arranged to select said driving speed by comparing the output level of said second detecting means with a predetermined threshold value.
Claim 22
Dependent Claim
49 words
A device according to claim 14, wherein said high-luminance detecting means includes a voltage comparator which compares the luminance level of the video signal with a predetermined reference level, and wherein the high-luminance part is determined when said voltage comparator detects that the luminance level exceeds said reference level.
Claim 23
Dependent Claim
30 words
A device according to claim 16, wherein said control means is further arranged to vary said threshold value according to the depth of field of said photo-taking lens optical system.
Claim 24
Dependent Claim
188 words
An automatic focus adjusting device comprising: a) image sensing means for converting an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) first detecting means for detecting a high-frequency component from the video signal; c) second detecting means for detecting, from the video signal, a signal corresponding to the sharpness of an edge part of the object image; d) third detecting means for detecting, from the video signal, a high-luminance part on said image sensing plane; e) driving means for varying the position of said photo-taking lens optical system relative to said image sensing plane in the direction in which output levels of said first and second detecting means increase; f) control means arranged to compare with a predetermined threshold value the level of the signal output from said second detecting means and corresponding to the sharpness of the edge part, and to change the driving speed of said driving means according to the result of comparison; and g) correction means for varying the setting of said threshold value according to an output of said third detecting means.
Claim 25
Dependent Claim
188 words
An automatic focus adjusting device comprising: a) image sensing means for converting an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) first detecting means for detecting a high-frequency component from the video signal; c) second detecting means for detecting, from the video signal, a signal corresponding to the sharpness of an edge part of the object image; d) third detecting means for detecting, from the video signal, a high-luminance part on said image sensing plane; e) driving means for varying the position of said photo-taking lens optical system relative to said image sensing plane in the direction in which output levels of said first and second detecting means increase; f) control means arranged to compare with a predetermined threshold value the level of the signal output from said second detecting means and corresponding to the sharpness of the edge part, and to change the driving speed of said driving means according to the result of comparison; and g) correction means for varying the setting of said threshold value according to an output of said third detecting means.
Claim 26
Dependent Claim
35 words
A device according to claim 20, wherein said control means is arranged to change the driving speed of said driving means at least by three steps according to the output of said second detecting means.
Claim 27
Dependent Claim
55 words
A device according to claim 21, wherein said correction means is arranged to change said threshold value in such a way as to keep the driving speed changeover position of said driving means unvarying relative to an in-focus point when the shape of a focusing characteristic curve is changed by a high degree of luminance.
Claim 28
Dependent Claim
31 words
A device according to claim 20, further comprising second correction means for changing said driving speed changing threshold value according to the depth of field of said photo-taking lens optical system.
Claim 29
Dependent Claim
146 words
An automatic focus adjusting device comprising: a) image sensing means for converting an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) focus adjusting means for adjusting the position of said photo-taking lens optical system relative to said image sensing plane; c) first detecting means for detecting from the video signal a first focus signal which corresponds to a focused state; d) second detecting means for detecting from the video signal a second focus signal the characteristic of which differs from that of said first focus signal; e) third detecting means for obtaining a third focus signal by adding said first and second focus signals; and f) control means for controlling the driving speed of said focus adjusting means by using said third focus signal and at least one of said first and second focus signals.
Claim 30
Dependent Claim
146 words
An automatic focus adjusting device comprising: a) image sensing means for converting an object image formed on an image sensing plane by a photo-taking lens optical system into a video signal; b) focus adjusting means for adjusting the position of said photo-taking lens optical system relative to said image sensing plane; c) first detecting means for detecting from the video signal a first focus signal which corresponds to a focused state; d) second detecting means for detecting from the video signal a second focus signal the characteristic of which differs from that of said first focus signal; e) third detecting means for obtaining a third focus signal by adding said first and second focus signals; and f) control means for controlling the driving speed of said focus adjusting means by using said third focus signal and at least one of said first and second focus signals.
Claim 31
Dependent Claim
45 words
A device according to claim 24, wherein said first focus signal is a high-frequency component of the video signal, and wherein said second focus signal is a signal component of the video signal related to the width of an edge part of the object image.
Claim 32
Dependent Claim
44 words
A device according to claim 25, wherein said control means is arranged to control the driving speed of said focus adjusting means on the basis of said second focus signal and a difference value of said third focus signal resulting from temporal changes thereof.
Claim 33
Dependent Claim
36 words
A device according to claim 26, wherein said control means is arranged to drive said focus adjusting means at a high speed when the level of said second focus signal is below a first threshold value.
Claim 34
Dependent Claim
46 words
A device according to claim 26, wherein said control means is arranged to control the driving speed of said focus adjusting means by comparing said difference value with a second threshold value when the level of said second focus signal is above a first threshold value.
Claim 35
Dependent Claim
50 words
A device according to claim 27, wherein said control means is arranged to set the driving speed of said focus adjusting means at a medium speed if said difference value is above a second threshold value when the level of said second focus signal is above said first threshold value.
Claim 36
Dependent Claim
50 words
A device according to claim 27, wherein said control means is arranged to set the driving speed of said focus adjusting means at a low speed if said difference value is below a second threshold value when the level of said second focus signal is above said first threshold value.
Claim 37
Dependent Claim
30 words
A device according to claim 26, wherein said control means is arranged to determine the driving direction of said focus adjusting means according to the polarity of said difference value.
References Cited (Backward Citations)
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