초록 ▼

A primary lens, which forms a primary image of an object on an image plane, is arranged to be positioned by a lens focusing motor. First and second auxiliary optical elements, which may be lenses or mirrors, produce respective first and second detection images of the object on respective first and s

A primary lens, which forms a primary image of an object on an image plane, is arranged to be positioned by a lens focusing motor. First and second auxiliary optical elements, which may be lenses or mirrors, produce respective first and second detection images of the object on respective first and second arrays of light sensors. One of these elements is reciprocated in continuously repeated periods or cycles to move its image back and forth continuously on the corresponding array. A signal processing circuit receives the outputs of the light sensors and produces a correlation pulse each time that the cycling element occupies the correlation position at which it brings the light distributions of the images into best correspondence on the respective arrays. The time and element position in each cycle at which this occurs are measures of the object distance. A circuit responds to the correlation pulse and to the relative positions of the cycling element and the primary lens, and controls the motor to make the final position of the primary lens correspond to the correlation position of the cycling element, this final position causing the primary image to be in best focus on the image plane. The relative positions of the cycling element and the primary lens are ascertained by magnetically actuated devices, by a mechanically operated switch, by a light operated switch, or by an arrangement which compares an element position signal to a primary lens position signal.

대표청구항 ▼

Apparatus for automatically focusing the image of an object, comprising a plurality of radiation responsive elements divided into two similar detector arrays, each of said elements being arranged to provide an electrical signal representative of the intensity of radiation impinging thereon, first au

Apparatus for automatically focusing the image of an object, comprising a plurality of radiation responsive elements divided into two similar detector arrays, each of said elements being arranged to provide an electrical signal representative of the intensity of radiation impinging thereon, first auxiliary optical means defining a first optical path for radiation from the object and for forming a first detection image thereof on solely one of said arrays, second auxiliary optical means defining a second optical path for radiation from the object and for forming a second detection image thereof on solely the other of said arrays, the positions and radiation distributions of said detection images on the corresponding arrays changing with changes in the relative positions of said auxiliary means and said arrays, and with changes in the object distance, there being for each such distance a one of the last-mentioned positions at which there is best correspondence of said distributions on said arrays, scanning means for relatively moving at least a portion of at least one of said auxiliary means and the corresponding one of said arrays progressively through a predetermined range of relative positions during a time period, said range including said one position at which there is said best correspondence of said distribution on said arrays for the existing object distance, signal processing means connected to said elements for comparing the signal from each of said elements of one of said arrays with the signal from the positionally corresponding one of said elements of the other of said arrays, and for summing the results of such comparisons to provide an output signal which exhibits a predetermined effect when said best correspondence of said distributions on said arrays is obtained during said period, primary optical means arranged for producing a primary image of the object on an image plane and capable of adjustment into any of a plurality of positions, said primary image being in best focus on said plane when the position of said primary optical means corresponds to the one of said relative positions in said range at which said effect is produced during said period, and responsive means including first means coupled to said signal processing means and said scanning means and responsive to said effect and to said relative movement of said auxiliary means and said arrays to effectively ascertain at which of said relative positions in said range said effect is produced during said period, and including second means coupled to said primary optical means to effectively ascertain the instantaneous position thereof, to compare said two ascertained positions, and to adjust said primary optical means as necessary to make said ascertained positions correspond.