Automatic focus adjusting device

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 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 among plural predetermined driving speeds according to the output level of said second focus signal and the depth of field of said photo-taking lens optical system, said control means being arranged to change threshold levels set to be used in changing and selecting said driving speeds from among said plural predetermined driving speeds according to the depth of field.

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 according to the depth of field so as to adaptively change said focus adjusting speed on the basis of the signal detected by said detecting means.

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.

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.

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.