PURPOSE: To attain automatic aperture function by providing a luminous amount detecting means and an automatic aperture device comprising an LCD and an LCD control/drive circuit to activate the control/drive circuit corresponding to the luminous amount of an object detected by a luminous amount detecting means.
CONSTITUTION: A control signal and a drive signal are supplied to an LCD8 from an input terminal 9 and the luminous amount is adjusted and controlled by utilizing the optical characteristic of a polarized filter and the twisted nematic field effect being the electrooptic effect of a nematic liquid crystal. The control/ drive circuit comprises inverters IC1∼IC6, resistors R1∼R5, capacitors C1, C2, a transistor TR1 and a blue cell BS1 as the luminous amount detecting means. The luminous amount of an object by the blue cell BS1 and a control signal of the LCD8 is controlled by an oscillating frequency decided by the resistor R1 and the capacitor C1, and the luminous amount transmitting through the LCD8 is adjusted through the change in the oscillating frequency.
KAWABATA KENJI
HAYASHI NOBUTAKA
