JPS57190463A - Television camera - Google Patents

Abstract

PURPOSE:To form always the optimum quality of a picture b changing an aperture correction value according to the aperture state of th diaphragm of a lens. CONSTITUTION:An aperture correction value is changed by th output voltage of a comparator driving circuit 10. Since the terminal of a delay line 13 is opened, an input signal e1 is reflected and returned to an input terminal and, when the electric angle of the delay line is theta, e1=ei costheta.epsilon<-js> and e2=ei.epsilon<js> are formed and an output signal of a differential amplifier is e1-e2=eiepsilon<-js> (costheta-1). A gain controlling circuit consisting of transistors 19-22, a current source 23 and a resistance 24 and the gain is controlled by an output signal from an amplifier 26. The gain controlled high frequency signal and the original signal are subtracted by a subtractor 25 and e2+K(e1-e2)=ei.e<-js>[1+K(1-costheta)]is found. The output signal is increased in prportion to the increment of frequency and shows the maximum at the frequency corresponding to costheta=-1. In said formula, K represents gain and the optimum quality of a picture can be always formed by controlling K.