Apparatus for automatically focusing a camera lens

Claim 2

An automatic focusing camera in which an automatic focusing operation is performed by detecting a high frequency component of a video signal which is obtained from an image sensor device at predetermined periods as a focus evaluating value, said automatic focusing camera comprising: first search means which moves a focus lens, in a first direction at a first speed, between an infinite focal point lens position and a nearest focal point lens position in incremental steps of first fixed size, wherein said infinite focal point lens position and said nearest focal point lens position define two extremes of a focal distance range of the lens, and produces a focus evaluating value for each step forming a first plurality of focus evaluating values wherein a maximum focus evaluating value in said plurality of focus evaluating values is a first maximum focus evaluating value, and second search means for continuously moving said focus lens, in a second direction opposite said first direction at a second speed being faster than said first speed, to a lens position one step adjacent to a lens position corresponding to said first maximum focus evaluating value, and thereafter, further moves said focus lens, in said second direction at a third speed being slower than said second speed, with incremental steps having a second size smaller than said first fixed size, and produces a focus evaluating value at each respective step forming a second plurality of focus evaluating values, wherein a maximum focus evaluating value in said second plurality of focus evaluating values is a second maximum focus evaluating value corresponding to an in-focus lens position.

Claim 3

An automatic focusing camera in which an automatic focusing operation is performed by detecting a high frequency component of a video signal which is obtained from an image sensor device at predetermined periods as a focus evaluating value, said automatic focusing camera comprising: lens position changing means for changing a relative position of a focus lens with respect to the image sensor device, first search means which causes said lens position changing means to move said focus lens, in a first direction at a first speed, between an infinite focal point lens position and a nearest focal point lens position in incremental steps of first fixed size, wherein said infinite focal point lens position and said nearest focal point lens position define two extremes of a focal distance range of the lens, and produces a focus evaluating value for each step forming a first plurality of focus evaluating values wherein a maximum focus evaluating value in said plurality of focus evaluating values is a first maximum focus evaluating value, and second search means which causes said lens position changing means to continuously move said focus lens, in a second direction opposite said first direction at a second speed being faster than said first speed, to a lens position one step adjacent to a lens position corresponding to said first maximum focus evaluating value, and thereafter, further causes said lens positioning means to move said focus lens, in said second direction at a third speed being slower than said second speed, with incremental steps having a size smaller than said first fixed size, and produces a focus evaluating value at each respective step forming a second plurality of focus evaluating values, wherein a maximum focus evaluating value in said second plurality of focus evaluating values is a second maximum focus evaluating value corresponding to an in-focus lens position.

Claim 4

An automatic focusing camera in which an automatic focusing operation is performed by detecting a high frequency component of a video signal which is obtained from an image sensor device at predetermined periods as a focus evaluating value, said automatic focusing camera comprising: lens position changing means for changing a relative position of a focus lens with respect to the image sensor device, first search means which causes said lens position changing means to move said focus lens, in a first direction at a first speed, between an infinite focal point lens position and a nearest focal point lens position in incremental steps of first fixed size, wherein said infinite focal point lens position and said nearest focal point lens position define two extremes of a focal distance range of the lens, and produces a focus evaluating value for each step forming a first plurality of focus evaluating values wherein a maximum focus evaluating value in said plurality of focus evaluating values is a first maximum focus evaluating value, and second search means which causes said lens position changing means to continuously move said focus lens, in a second direction opposite said first direction at a second speed being faster than said first speed, to a lens position one step adjacent to a lens position corresponding to said first maximum focus evaluating value, and thereafter, further causes said lens positioning means to move said focus lens, in said second direction at a third speed being slower than said second speed, with incremental steps having a size smaller than said first fixed size, and produces a focus evaluating value at each respective step forming a second plurality of focus evaluating values, wherein a maximum focus evaluating value in said second plurality of focus evaluating values is a second maximum focus evaluating value corresponding to an in-focus lens position.