Auto focus system
AssigneeHoneywell Inc.
InventorNorman L. Stauffer
Life of this patent
Estimating the term…
Abstract
Range finding equipment for use with optical systems and particularly low cost cameras to provide for proper focus of a remote object. A small number of radiation detectors are positioned to receive radiation in first and second patterns from the object to be focused upon through an auxiliary lens. The outputs of the detectors are processed to produce a resultant signal which is indicative of the position for proper focus. The auxiliary lens is coupled to the taking lens of the camera and means are provided for moving both lenses in accordance with the resultant signal so that the taking lens is in a proper focus position. The detectors may be photo diodes to facilitate the use of log signals to thereby compensate for differences in intensity of the scene being viewed.
Claims25
Range determination apparatus for use with an optical system including first lens means movable along a first axis to a first position in which an image of a remote object is in proper focus at a predetermined plane comprising:
- second lens means coupled to the first lens means so as to move therewith along a second axis parallel to and displaced from the first axis and operable to transmit radiation from the object;
- third lens means mounted to receive the radiation transmitted by the second lens means so as to form first and second images of the exit pupil of the second lens means;
- first and second radiation detector means mounted to receive the first image of the exit pupil of the second lens means, the first and second radiation detector means each being operable to produce an output signal indicative of the radiation received thereby, the output signals of the first and second radiation detector means being substantially equal when the first lens means is proximate the first position and normally being unequal when the first lens means is on either side of the first position;
- third and fourth radiation detector means mounted to receive the second image of the exit pupil of the second lens means, the third and fourth radiation detector means each being operable to produce an output signal indicative of the radiation received thereby, the output signals of the third and fourth radiation detector means being substantially equal when the first lens means is proximate the first position and normally being unequal when the first lens means is on either side of the first position;
- and
- signal receiving means connected to the first, second, third and fourth radiation detector means to receive the output signals therefrom and produce a resultant output signal indicative of whether the first lens means should be moved in order to occupy the first position.
Automatic focussing apparatus for use with a camera having a film plane and taking lens movable along a first axis and operable to direct radiation from a scene containing an object to be focused upon to the film plane, comprising:
- focus lens means including at least a portion movable with the taking lens means along a second axis parallel to but displaced from the first axis and operable to produce first and second radiation patterns of the scene, the patterns being similar and in a relative first condition when the taking lens means is in a first position to focus an image of the object properly at the film plane, in a relative second condition when the taking lens means is on a first side of the first position and in a relative third condition when the taking lens means is on a second side of the first position;
- a first radiation detector positioned to receive radiation corresponding to a first position in the first pattern and to produce a first signal in accordance therewith;
- a second radiation detector positioned to receive radiation corresponding to a second position in the first pattern and to produce a second signal in accordance therewith;
- a third radiation detector positioned to receive radiation corresponding to a first position in the second pattern and to produce a third signal in accordance therewith;
- a fourth radiation detector positioned to receive radiation corresponding to a second position in the second pattern and to produce a fourth signal in accordance therewith;
- and
- signal receiving means connected to said first, second, third and fourth detectors to receive the first, second, third and fourth signals respectively and to produce a resultant signal representative of the absolute value of the difference between the log of the first signal and the log of the fourth signal less the absolute value of the difference between the log of the second signal and the log of the third signal, the resultant signal having a first characteristic when the patterns are in the relative second condition and having a second characteristic when the patterns are in the relative third condition, as an indication that the taking lens means is on the first or second side respectively of the first position.
Range determination apparatus for use with an optical system including lens means operable to transmit radiation from a remote object movable to a first position in which an image of the object is in proper focus at a predetermined plane comprising:
- means receiving radiation transmitted by the lens means and operable to form first and second images of at least a portion of the exit pupil of the lens means;
- first, second, third and fourth radiation detector means, each operable to produce an output signal which is a log function of the radiation received thereby;
- means mounting the first and second radiation detector means to receive the first image of the exit pupil of the lens means;
- means mounting the third and fourth radiation detector means to receive the second image of the exit pupil of the lens means;
- and
- signal receiving means connected to the first, second, third and fourth detector means to receive the output signals therefrom and to produce a resultant output signal indicative of whether the lens means should be moved in order to occupy the first position.
Automatic focusing apparatus for use with a camera having a film plane and first lens means moveable along a first axis and operable in a focus position to direct a focused image of a remote object to the film plane, comprising:
- second lens means including focus lens means connected to and moveable in a predetermined ratio with the first lens means along a second axis substantially parallel to but displaced from the first axis and operable to transmit radiation from the remote object;
- detector means mounted to receive radiation transmitted by said focus lens means and to produce an output signal which has a first characteristic when the first lens means is on one side of the focus position, a second characteristic when the first lens means is on the other side of the focus position and a reference characteristic when the first lens means is proximate the focus position;
- motive means operable to move the first and second lens means along the first and second axes respectively;
- and
- signal receiving means connected to said motive means and to said detector means to receive the output signal, said signal receiving means being responsive to the reference characteristic to cause said motive means to stop the motion of the first and second lens means.
Dependencies are inferred from the claim text.