초록 ▼

In the device disclosed, an image formed by an optical system is scanned by an image sensor composed of independently arranged photoelectric transducing elements to produce an image scanning signal. A detecting circuit detects the variation of the brightness between the adjacent image elements as a

In the device disclosed, an image formed by an optical system is scanned by an image sensor composed of independently arranged photoelectric transducing elements to produce an image scanning signal. A detecting circuit detects the variation of the brightness between the adjacent image elements as a measure of the sharpness of the image and the focus of the optical system. The focus detection accuracy is improved by non-linear transformation of the brightness variation signal with a non-linear transformation circuit that weighs the brightness variation signal on the basis of the signal level.

대표청구항 ▼

A through-the-lens type focus detecting device usable with exchangeable lens systems having different optical factors, comprising: (A) means for sensing radiation coming from an object and passed through a lens system used, said sensing means producing an electrical signal corresponding to the recei

A through-the-lens type focus detecting device usable with exchangeable lens systems having different optical factors, comprising: (A) means for sensing radiation coming from an object and passed through a lens system used, said sensing means producing an electrical signal corresponding to the received radiation; (B) means for receiving and processing said electrical signal produced by said sensing means and for discerning a focusing condition of said used lens system with respect to said object; and (C) changeover means for changing the accuracy of the focus detection of the device in accordance with the optical factor of said used lens system, said changeover means being arranged to change the degree of accuracy of the device by changing the operational characteristic of the processing means in accordance with the optical factor of the used lens system; said processing means including means for non-linearly converting the electrical signal produced by the sensing means, and the changeover means including means for selecting a non-linear converting characteristic of the non-linear converting means in accordance with the optical factor of the lens system used.