Abstract: An automatic diaphragm control device for the objective of a television camera, utilizing a video signal coming from the television camera to effect the diaphragm control The present invention provides a device including a fixed photometric circuit of a drastic peak characteristic in a part of a variable photometric circuit so as to be readily switched to perform a drastic peak photometric adjustment, in addition to an ordinary variable photometric adjustment, and also provides an automatic diaphragm control device of variable photometry type used in a television camera in which the variable photometric circuit is also arranged so as to be switched between the variable peak mode and the variable average mode so that a simple operation of changing over on one and the same circuit permits the variable photometry of both types to be selectively performed in order to obtain not only the drastic peak photometric characteristic but also versatile photometric characteristics optimized for various requirements.

Abstract: The present invention relates to an automatic diaphragm control device for use with a CCTV camera which has recently found many applications.The present invention provides an automatic diaphragm control device for use with a CCTV camera adapted to provide an automatically diaphragm controllable lens system having a light measuring mode which can be continuously varied at will adjacently to or remotely from the camera objective depending on the condition of an object to be picked up and permitting a changeover to be easily achieved between an automatic diaphragm control mode and a remote diaphragm control mode, if desired, to meet needs of the CCTV system.

Abstract: The present invention relates to an automatic diaphragm control device for use with a CCTV camera in which a video signal applied from the CCTV camera is utilized for diaphragm control, and provides an automatic diaphragm control device for use with the CCTV camera, comprising first means for continuous control of the video signal with respect to an absolute brightness of an object to be picked up, second means for continuous control of a proportion of the video signal corresponding to a bright portion in the whole picture when a ratio of the bright portion to a dark portion of this object is relatively high, and third means for stabilization of a control signal, which has been obtained by said first and second means and then rectified, with respect to a source voltage.

Abstract: A control circuit for automatically opening and closing the diaphragm of the objective lens of a closed circuit television (CCTV) camera, including a variable gain inverting amplifier for amplifying and inverting video signals from the camera, a voltage doubler and rectifier coupled to the output of the inverting amplifier, a reference voltage generator, a diaphragm control assembly for comparing said reference voltage with signals output from said voltage doubler and opening and closing said diaphragm in response to the results of said comparison, and a series circuit including a clipping diode and variable resistor coupled between the input and output of the inverting amplifier. The clipping diode clips negative going portions of signals output from said inverting amplifier and adjustment of said variable resistor selects different light modes by controlling the degree of clipping.

Abstract: A control circuit for automatically opening and closing the diaphragm of the objective lens of a closed circuit television (CCVT) camera including a variable gain inverting amplifier for amplifying and inverting video signals from the camera, a voltage doubler and rectifier with an adjustable capacitor coupled to the output of the inverting amplifier, a voltage level shifter coupled to the output of the voltage doubler for lowering signals output therefrom by a predetermined voltage, a power supply for providing bias voltage to said control circuit, an intermediate voltage supply circuit for providing a signal reference voltage to said circuit which is intermediate to the value of said bias voltage, and a comparator circuit for comparing the intermediate voltage with the signal output from said level shifter and opening or closing the diaphragm based on the results of the comparison.

Abstract: A diaphragm control for a video camera is disclosed and controls the camera diaphragm in response to the camera video output. The camera video output signal is adjustably weighted to vary the value of the dark portions of signal with respect to the light portions through the use of a selective polarity invertible amplifier which holds the average signal strength constant as the weight of the light and dark portions is varied. The output of the polarity invertible amplifier is averaged and then compared with a reference intensity signal. The output of the comparator is used to control the camera diaphragm.