PURPOSE: To make the brightness distribution of the image on a line sensor surface into the same shape and same direction and to prevent erroneous decision of focusing by inclining the edges of the aperture parts of a diaphragm mask disposed on the front surface of two re-image-forming lenses from the perpendicularity to the aperture plane of the diaphragm.
CONSTITUTION: The distribution of the brightness on a line sensor C surface by re-image-forming lenses 8, 10 is of the same shape but the directions are opposite from each other and the output reflecting the luminance distribution of the same subject is not obtd. The cause for such phenomenon lies in that the ends of the images are darker and that the luminous flux is vignetted by the edge of the aperture of a diaphragm mask 30. Therefore apertures 30a, 30b are respectively formed by inclining the blanking direction for the aperture of the mask 30 from the perpendicularlity to the mask plane. The brightness distribution of the image plane by the re-image-forming lenses on the sensor C surface is thus made into the same shape and the same direction. The erroneous decision of the focus detection is thus prevented by the simple construction.
MUKAI HIROSHI
KAWAMURA KUNIO
