US Patent 7787760 Lens aperture-adjustment device and closed circuit television camera

A lens aperture-adjustment device of a closed circuit television camera for capable of switching between automatic and manual adjustments of lens aperture is provided. The device includes a geared motor for driving aperture blades of a lens aperture mechanism; a drive circuit for driving the geared motor in response to a first drive signal for automatic adjustment or a second drive signal for manual adjustment; a comparison circuit for making a comparison between a lightness information signal responsive to the imaging environment and a first reference signal and outputting the first drive signal; a differential amplifier to which a manual adjustment signal entered by an operator and a second reference signal for defining the limit value of the drive amount of the geared motor are input, the differential amplifier for outputting the second drive signal; and a selection circuit for connecting the first drive signal or the second drive.