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US 4,309,098 AGranted
Autofocus cine camera having automatic variable speed focusing
AssigneePolaroid Corporation
InventorEdwin K. Shenk
Life of this patent
Estimating the term…
Abstract
A photographic camera having an adjustable focus lens is provided with an automatic focus control system to focus said lens at one focusing rate if the lens focusing movement necessary to focus said lens to the proper subject-in-focus position is greater than a predetermined magnitude, and at another focusing rate if said necessary lens focusing movement is equal to or less than said predetermined magnitude.
Claims14
In an autofocusing camera of the type having,
- an image plane,
- an adjustable focus lens mounted for displacement over a given operational range where it serves to focus images of subjects positioned within a range of subject distances at said image plane,
- an ultrasonic rangefinder for deriving a subject distance signal representative of the distance to a particular subject within said range of subject distances, the improvement comprising:
- energizable drive means responsive to said subject distance signal for displacing said lens at one rate in a particular direction if the magnitude of lens displacement necessary to focus an image of said particular subject at said image plane is greater than one-eighth of the entire focusing range of said adjustable focus lens and at another rate in said same particular direction if said necessary lens displacement magnitude is equal to or less than said one-eighth of the entire focusing range of said adjustable focus lens.
1 more element
In an autofocusing camera of the type having,
- an image plane,
- an adjustable focus lens mounted for displacement over a given operational range where it serves to focus images of subjects positioned within a range of subject distances at said image plane,
- an ultrasonic rangefinder for deriving a subject distance signal representative of the distance to a particular subject within said range of subject distances,
- means responsive to said subject distance signal for deriving a lens movement signal representative of the lens displacement necessary to displace said lens from a present position to one selected in accordance with said subject distance signal so as to focus an image of said particular subject at said image plane, the improvement comprising:
- energizable drive means for displacing said lens an amount in correspondence with said lens movement signal at one rate in a particular direction while the magnitude of said lens movement signal is less than or equal to a signal corresponding to one-eighth of the entire focusing range of said adjustable focus lens and at another rate in said same particular direction while said magnitude of said lens movement signal is greater than said predetermined magnitude.
2 more elements
Dependencies are inferred from the claim text.