Other

Tetsuji Inoue

Masao Wada

Masayuki Sugawara

Haruo Tominaga

Hideaki Sugiura

Shinobu Nakamura

Hiroyuki Horiguchi

Ryoji Kumaki

Tadashi Sasaki

Satoshi Yahagi

In a focusing state determining device for determining a focusing state of a taking lens, an object light entering the taking lens is captured by focusing state determination imaging elements provided separately from a video imaging element, and the focusing state is determined according to luminance signals outputted from the focusing state determination imaging elements. Any error of determination of the focusing state induced by saturation of the luminance signals in imaging an object of high luminance is prevented by adjusting the gains of the image signals outputted from the focusing state determination imaging elements or the charge accumulation times of the focusing state determination imaging elements. High-frequency components are determined from the luminance signals obtained from the focusing state determination imaging elements (A, B, C), and the focus evaluation value is determined by integration thereof. An automatic gain control circuit ( ) adjusts the gains of the luminance signals so that the maximum levels of the luminance signals may not reach the saturation levels.

Device for determining focused state of taking lens

A beam splitter ( )for splitting light in a wavelength range of about 500 nm to about 600 nm is arranged in a relay optical system of a taking lens ( ). A green light beam reflected from the beam splitter ( ) is directed through a relay lens (R ) to a focusing state determination imaging unit ( ). The imaging unit ( ) comprises three imaging elements (A, B, C) for capturing the directed green light beam to determine the focusing state. Thus, a device for determining the focusing state of the taking lens is provided, in which the green light beam is separated as an object light for determining the focusing state from the object light entering the taking lens ( ), so that the focusing state can be determined with high accuracy on the basis of the high-frequency components of the image signal generated by capturing the green light beam by means of the imaging elements (A, B, C) having different optical path lengths.

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Tokyo, Japan

Tetsuji Inoue