Abstract An improvement in light-stop regulating systems for motion picture cameras characterized by a resistance bridge circuit including a photoconductor element designed to be illuminated by incident light reflected from a mirror provided on rotary shutter blades and an ammeter for controlling the stop blade for regulating the light incident on the photoconductor element. The bridge circuit also includes capacitors connected in parallel respectively with two of resistors of the bridge, each one end of which is together connected to one end of the ammeter whose other end is connected to one end of said photoconductor element. There is also provided a time-constant circuit which is connected in parallel with at least one of the capacitors and is formed by a capacitor and a resistor in series, the time-constant circuit being connected with a switch which is inter-locked with the rotary shutter blades so as to operate ON-and-OFF in synchronism with each rotation of the shutter blades and to open automatically when the shutter blades are in the still state.
A light-stop regulating mechanism for motion picture cameras including a photoconductive element, a mirror provided on rotary shutter blades for directing light on said photoconductive element anD a film and electromagnetic means for controlling the light incident on said photoconductive element, comprising a resistor bridge circuit having three resistors and said photoconductor element in respective legs thereof, first and second capacitors connected across respective resistors of adjacent legs of said bridge, said electromagnetic means having an ammeter including a coil connected between one end of said phtotoconductive element and the point of connection of said first and second capacitors across the output of said bridge, and time constant circuit means connected across one of said first and second capacitors and responsive to rotation of said shutter blade for controlling the time constant of said bridge circuit, said time constant circuit means including a third capacitor and a further resistor connected in series across said one of said first and second capacitors and a switch interlocked with said rotary shutter blade and connected across said third capacitor so as to open and close in synchronism with each rotation of the shutter blade and open automatically when said shutter blade is in the still state.
Claim 2
Dependent Claim
203 words
A light-stop regulating mechanism for motion picture cameras including a photoconductive element, a mirror provided on rotary shutter blades for directing light on said photoconductive element anD a film and electromagnetic means for controlling the light incident on said photoconductive element, comprising a resistor bridge circuit having three resistors and said photoconductor element in respective legs thereof, first and second capacitors connected across respective resistors of adjacent legs of said bridge, said electromagnetic means having an ammeter including a coil connected between one end of said phtotoconductive element and the point of connection of said first and second capacitors across the output of said bridge, and time constant circuit means connected across one of said first and second capacitors and responsive to rotation of said shutter blade for controlling the time constant of said bridge circuit, said time constant circuit means including a third capacitor and a further resistor connected in series across said one of said first and second capacitors and a switch interlocked with said rotary shutter blade and connected across said third capacitor so as to open and close in synchronism with each rotation of the shutter blade and open automatically when said shutter blade is in the still state.
Claim 3
Dependent Claim
28 words
A light-stop regulating mechanism as defined in claim 1 wherein a source of direct current voltage is connected across said respective resistors of adjacent legs of said bridge.
Claim 4
Dependent Claim
26 words
A light-stop regulation mechanism as defined in claim 2 wherein said electromagnetic means includes a movable stop blade for controlling the light passing to said mirror.
Claim 5
Dependent Claim
20 words
A light-stop regulation mechanism as defined in claim 3 wherein a further resistor is connected in series with said switch.