Automatic focus indicating device for camera
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorHarumi Aoki
Life of this patent
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Abstract
A device for detecting and indicating the focus position of a camera from the contrast signal. A peak value detector holds the maximum value of a contrast signal produced in the camera. The stored signal is compared with the contrast signal itself as the direction of the lens is reversed and the focus signal is generated when the two signals are equal. The values stored in the peak detecting circuit is reset as the shutter button is pushed as the lens commences movement in the forward direction to prevent erroneous generation of the focus signal.
Claims7
A device for detecting and a indicating a focus position in a camera from a single contrast signal produced in response to an image of an object to be photographed with said camera comprising:
- means for producing said contrast signal in response to said image;
- means for detecting the directions of movement of a lens;
- a peak holding circuit for storing the maximum value of said contrast signal;
- reset pulse generating circuit means for generating a reset pulse for resetting the contents stored in said peak hold circuit;
- a comparator circuit for comparing a signal stored in said peak holding circuit means and said contrast signal for producing a focus signal when said contrast signal is equal to or greater than said signal stored in said peak holding circuit means;
- and means for producing an indication in response to said focus signal.
Dependencies are inferred from the claim text.