초록 ▼

In a focus condition detecting device wherein an object image formed by an objective lens of a camera is re-imaged as first and second images on first and second photocell arrays through a pair of re-imaging lenses, a pair of plano-convex lenses are used as the re-imaging lenses to improve the accur

In a focus condition detecting device wherein an object image formed by an objective lens of a camera is re-imaged as first and second images on first and second photocell arrays through a pair of re-imaging lenses, a pair of plano-convex lenses are used as the re-imaging lenses to improve the accuracy of focus condition detection. The device is formed into a module and the plano-convex lenses are formed on a transparent plate supported on a main body of the module. An extremely thin masking member for blocking a part of light rays incident on the plano-convex lenses to form the first and second images is sandwiched between the transparent plate and a surface of the module main body. This arrangement prevents the masking member from rising and/or warping which otherwise causes inconsistency in luminous levels between the first and second images on the first and second photocell arrays. Various examples of the arrangement of the masking member to prevent its rising and/or warping are proposed.

대표청구항 ▼

A focus condition detecting device for a camera having an objective lens which forms an object image, said device comprising: image sensor means which has first and second photocell arrays extending in the direction perpendicular to the main optical axis of said objective lens and arranged opposite

A focus condition detecting device for a camera having an objective lens which forms an object image, said device comprising: image sensor means which has first and second photocell arrays extending in the direction perpendicular to the main optical axis of said objective lens and arranged opposite to one another with respect to the main optical axis of said objective lens; a transparent plate having first and second flat surfaces perpendicular to the main optical axis of said objective lens and arranged to face said first flat surface to said image sensor means; a pair of re-imaging lenses formed on said transparent plate to re-image said object image as first and second images on said first and second photocell arrays respectively so that the distance between the corresponding points of said first and second images on said first and second photocell arrays varies with the focus condition of said objective lens, each said re-imaging lens having a convex surface on said first flat surface of said transparent plate to form a plano-convex lens; a support member for supporting at least said transparent plate; and masking means having a pair of openings and blocking a part of light rays incident on said re-imaging lenses to form said first and second images, in a symmetrical manner with respect to the main optical axis of said objective lens, said masking means being sandwiched between said second flat surface of said transparent plate and said support member with said openings aligned with said re-imaging lenses.