초록 ▼

The present invention relates to a method and a system for detecting the sharpness of the object image by detecting the amount of the component of a certain specified frequency, whereby the object image formed by means of an image forming optical system is detected by an image sensitive element cons

The present invention relates to a method and a system for detecting the sharpness of the object image by detecting the amount of the component of a certain specified frequency, whereby the object image formed by means of an image forming optical system is detected by an image sensitive element consisting of a number of fine photo sensitive elements arranged respectively integrated on one plane, while the outputs of the above mentioned photo sensitive elements are delivered out one after another in accordance with the arrangement order of the above mentioned elements by means of a signal time series means so as to carry out an electrical scanning of the above mentioned object image in such a manner that the then obtained scanning outputs of the object image are successively converted by means of an A - D (analogue-digital) converting means into digital signals which are put in a small computer in which an estimation function for estimating the amount of the component of a certain specified frequency in the spectrum of the spacial frequencies of the object light beam forming the above mentioned object image is programmed in advance.

대표청구항 ▼

An automatic focusing system comprising: (A) an image forming optical system having an optical axis and shiftable along the axis so as to form an object image on a predetermined imaging plane; (B) driving means operatively coupled with said optical system for shifting the optical system along the op

An automatic focusing system comprising: (A) an image forming optical system having an optical axis and shiftable along the axis so as to form an object image on a predetermined imaging plane; (B) driving means operatively coupled with said optical system for shifting the optical system along the optical axis; (C) image sensing means comprising n photosensitive elements addressed differently from each other one plane, said sensing means being disposed at positions to receive the object image formed by the optical system on said imaging plane, said n-photosensitive elements serving for producing respective output signals corresponding to the light intensity impinging thereon; (D) scanning means for repeatedly scanning the object image on the imaging plane during the shifting of the optical system by said driving means and for sequentially sending out each analogue output of said n-photosensitive elements of said image sensing means in the order of each address of said n-photosensitive elements, said scanning means being electrically connected to each of said n-photosensitive elements; (E) A - D converting means to convert each analogue output of the n-photosensitive elements being sent out sequentially by said scanning means into a digital signal, said converting means being electrically connected to said image sensing means; (F) a processing device for consecutively taking each address signal of the n-photosensitive elements addressed in turn by said scanning means and the digital signals being produced by said A - D converting means and for evaluating the distribution of the specific spatial frequency spectrum in the image light beam forming the object image; on the basis of a Fourier-function; wherein said processing means includes: (F-1) a function value generating means to produce a sine-cosine function value of said specific spatial frequency on each address of the n-photosensitive elements, said generating means being electrically connected to said scanning means for producing the function value in response to each address signal; (F-2) multiplying means to calculate a product of said sine-cosine function value and the digitally converted value of thE output of the photosensitive element at the address corresponding thereto; said multiplying means being electrically connected to said function value generation means and said A-D converting means; (F-3) first accumulating means to consecutively add the values calculated by said multiplying means cumulatively for calculating the total sum of said products on all of the n-photosensitive elements, said accumulating means being electrically connected to said multiplying means; (F-4) second accumulating means to consecutively add the digital signals being produced by said A-D converting means cumulatively for calculating the total sum of said digital signals on all of the n-photosensitive elements, said accumulating means being electrically connected to said A-D converting means; (F-5) dividing means to divide the value calculated by said first accumulating means by the value calculated by said second accumulating means, said dividing means being electrically connected to said first and second accumulating means; (F-6) first register means to record the value calculated by said dividing means as an l′th (l=1, 2, 3, . . .) scan is completed when the scanning of the object image is repeated several times during the shifting of the optical system by the driving means, said register means being electrically connected to said dividing means; (F-7) second register means to record the calculated value of said dividing means as an (l-1)th scan is completed when the scanning of the object image is repeated several times during the shifting of the optical system by the driving means, said second register means being electrically connected to said first register means and recording the value calculated by said dividing means as the (l-1)th scan on said first register means when l′th scan is completed; and (F-8) comparing means to judge which one of the value recorded by said first and second register means is larger than the other when each scan is completed, said comparing means being electrically connected to said first and second register means and producing a predetermined control signal when the values recorded by said registers become at least equal to each other; and (G) control circuit means to stop said driving means in response to said predetermined control signal produced by said comparing means, said circuit means being electrically connected to said driving means and said comparing means; so as to achieve automatic focusing of the image forming optical system on the object.